(Linux Professional Institute Certification)
a

– General Linux 1 –

.˜. /V\ // \\ @._.@

by: geoffrey robertson geoffrey@zip.com.au

$Id: slides.tex,v 1.9 2003/05/30 04:45:24 waratah Exp $

c 2002 Geoffrey Robertson. Permission is granted to make and distribute verbatim copies or modified versions of this document provided that this copyright notice and this permission notice are preserved on all copies under the terms of the GNU General Public License as published by the Free Software Foundation— either version 2 of the License or (at your option) any later version.

a Copyright

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List of Slides

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General Linux 1

• (1.3) GNU and UNIX Commands [30] • (2.4) Devices, Linux Filesystems & FHS [21] • (2.6) Boot, Initialisation, Shutdown, Runlevels [6] • (1.8) Documentation [8] • (2.11) Administrative Tasks [24]

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103 – (1.3) GNU and UNIX Commands [30]
1. Work on the command line [4] 2. Process text streams using filters [7] 3. Perform basic file management [2] 4. Use streams, pipes, and redirects [3] 5. Create, monitor, and kill processes [7] 6. Modify process execution priorities [2] 7. Search text files using regular expressions [3] 8. Perform basic file editing operations using vi [2]

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103.1 – Work on the command line [4]
103.1 – Objective
Candidate should be able to interact with shells and commands using the command line. This includes typing valid commands and command sequences, defining, referencing and exporting environment variables, using command history and editing facilities, invoking commands in the path and outside the path, using command substitution, applying commands recursively through a directory tree and using man to find about commands.

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103.1 – Key files, terms and utilities
•. • bash • echo • env • exec • export • man • pwd • set • unset • ˜.bash history • ˜/.profile

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103.1 – test
this is the beginning

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103.1 – test
this is the beginning blah

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103.1 – test
this is the beginning blah blah blah note... thing

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103.1 – test
this is the beginning blah blah blah blah note... thing

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103.1 – Shell Prompt
The command prompt is held in the shell variable $PS1 (Prompt String 1).

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103.1 – Shell Prompt
The command prompt is held in the shell variable $PS1 (Prompt String 1). • Simple User prompt: $ echo $PS1 \$ $ ←

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103.1 – Shell Prompt
The command prompt is held in the shell variable $PS1 (Prompt String 1). • Simple User prompt: $ echo $PS1 \$ $ • Fancy user prompt: $ export PS1="[\u@\\h:\W]\$ " ← [geoffrey@marsbar:geoffrey]$ ←

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103.1 – Shell Prompt
The command prompt is held in the shell variable $PS1 (Prompt String 1). • Simple User prompt: $ echo $PS1 \$ $ • Fancy user prompt: $ export PS1="[\u@\\h:\W]\$ " ← [geoffrey@marsbar:geoffrey]$ • Fancy prompt for the superuser: [root@marsbar root]# echo $PS1 ← \[\033[1;31m\][\u@\h \W]# \[\033[0m\] [root@marsbar root]# ←

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103.1 – Command Execution
In order for bash to execute a command entered at the prompt, the command must be one of the following:

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103.1 – Command Execution
In order for bash to execute a command entered at the prompt, the command must be one of the following: • An alias: $ alias ll=’ls -l’ ←

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103.1 – Command Execution
In order for bash to execute a command entered at the prompt, the command must be one of the following: • An alias: $ alias ll=’ls -l’ ← • A bash builtin: e.g. $ cd ←

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103.1 – Command Execution
In order for bash to execute a command entered at the prompt, the command must be one of the following: • An alias: $ alias ll=’ls -l’ ← • A bash builtin: e.g. $ cd ← • An executable in a directory that is listed in the $PATH variable: $ which ls ← /bin/ls

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103.1 – Command Execution
In order for bash to execute a command entered at the prompt, the command must be one of the following: • An alias: $ alias ll=’ls -l’ ← • A bash builtin: e.g. $ cd ← • An executable in a directory that is listed in the $PATH variable: $ which ls ← /bin/ls • Explicitly defined by absolute or relative path $ ˜/my scripts/my.sh ← hi $ cd ˜/my scripts ← $ ./my.sh ←

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103.1 – PATH
The PATH environmental variable holds a list of directories. These directories hold executable programs.

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103.1 – PATH
The PATH environmental variable holds a list of directories. These directories hold executable programs. • View the PATH variable: $ echo $PATH /usr/kerberos/bin:/bin:/usr/bin:/usr/bin/X11:\ /usr/local/bin:/usr/bin:/usr/X11R6/bin:/home/\ geoffrey/bin:/home/geoffrey/bin

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103.1 – PATH
The PATH environmental variable holds a list of directories. These directories hold executable programs. • View the PATH variable: $ echo $PATH /usr/kerberos/bin:/bin:/usr/bin:/usr/bin/X11:\ /usr/local/bin:/usr/bin:/usr/X11R6/bin:/home/\ geoffrey/bin:/home/geoffrey/bin • General user PATH is configured in /etc/profile

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103.1 – PATH
The PATH environmental variable holds a list of directories. These directories hold executable programs. • View the PATH variable: $ echo $PATH /usr/kerberos/bin:/bin:/usr/bin:/usr/bin/X11:\ /usr/local/bin:/usr/bin:/usr/X11R6/bin:/home/\ geoffrey/bin:/home/geoffrey/bin • General user PATH is configured in /etc/profile • PATH may be modified in ˜/.bash profile

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103.1 – Command history

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103.1 – Command history
• Previously used commands accessed through the use of the arrow keys

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103.1 – Command history
• Previously used commands accessed through the use of the arrow keys • The size of the history file is determined by HISTSIZE

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103.1 – Command history
• Previously used commands accessed through the use of the arrow keys • The size of the history file is determined by HISTSIZE • The command history lists the last HISTSIZE commands $ history ... 1007 xhost + 1008 history $

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103.1 – Command history
• Previously used commands accessed through the use of the arrow keys • The size of the history file is determined by HISTSIZE • The command history lists the last HISTSIZE commands $ history ... 1007 xhost + 1008 history $ • The command fc opens the command in the default editor for editing $ fc 1007 xhost + ˜ ˜

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103.1 –

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103.1 –

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103.2 – Process text streams using filters [7]
103.2 – Objective
Candidate should be able to apply filters to text streams. Tasks include sending text files and output streams through text utility filters to modify the output, and using standard UNIX commands found in the GNU textutils package.

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103.3 – Perform basic file management [2]
103.3 – Objective
Candidate should be able to use the basic UNIX commands to copy, move, and remove files and directories. Tasks include advanced file management operations such as copying multiple files recursively, removing directories recursively, and moving files that meet a wildcard pattern. This includes using simple and advanced wildcard specifications to refer to files, as well as using find to locate and act on files based on type, size, or time.

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103.4 – Use streams, pipes, and redirects [3]
103.4 – Objective
Candidate should be able to redirect streams and connect them in order to efficiently process textual data. Tasks include redirecting standard input, standard output, and standard error, piping the output of one command to the input of another command, using the output of one command as arguments to another command and sending output to both stdout and a file.

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103.5 – Create, monitor, and kill processes [7]
103.5 – Objective
Candidate should be able to manage processes. This includes knowing how to run jobs in the foreground and background, bring a job from the background to the foreground and vice versa, start a process that will run without being connected to a terminal and signal a program to continue running after logout. Tasks also include monitoring active processes, selecting and sorting processes for display, sending signals to processes, killing processes and identifying and killing X applications that did not terminate after the X session closed.

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103.5 – Create, monitor, and kill processes [7]
103.5 – Objective
Candidate should be able to manage processes. This includes knowing how to run jobs in the foreground and background, bring a job from the background to the foreground and vice versa, start a process that will run without being connected to a terminal and signal a program to continue running after logout. Tasks also include monitoring active processes, selecting and sorting processes for display, sending signals to processes, killing processes and identifying and killing X applications that did not terminate after the X session closed.

103.5 – Key files, terms and utilities
• ps • pstree • top • kill • nohup • jobs • bg • fg •& • ˆZ

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103.5 – Processes
• A process is an executable loaded in memory. • Linux is a multitasking operating system and so runs many processes concurrently.

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103.5 – Processes
• A process is an executable loaded in memory. • Linux is a multitasking operating system and so runs many processes concurrently. • INIT (PID 1) is the mother of all processes.

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103.5 – Processes
• A process is an executable loaded in memory. • Linux is a multitasking operating system and so runs many processes concurrently. • INIT (PID 1) is the mother of all processes. • Programs, daemons, shells and commands are all processes.

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103.5 – Processes
• A process is an executable loaded in memory. • Linux is a multitasking operating system and so runs many processes concurrently. • INIT (PID 1) is the mother of all processes. • Programs, daemons, shells and commands are all processes. • The kernel automatically manages processes.

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103.5 – Processes
• A process is an executable loaded in memory. • Linux is a multitasking operating system and so runs many processes concurrently. • INIT (PID 1) is the mother of all processes. • Programs, daemons, shells and commands are all processes. • The kernel automatically manages processes. • Normally processes live, execute and die without intervention from users.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed. Process ID (PID): Every process has a unique number assigned to it when it is started.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed. Process ID (PID): Every process has a unique number assigned to it when it is started. User ID and Group ID: Processes have the privileges associated with the user / group who started them.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed. Process ID (PID): Every process has a unique number assigned to it when it is started. User ID and Group ID: Processes have the privileges associated with the user / group who started them. Parent processes (PPID): Shell processes are descendants of init and commands run from them are child processes.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed. Process ID (PID): Every process has a unique number assigned to it when it is started. User ID and Group ID: Processes have the privileges associated with the user / group who started them. Parent processes (PPID): Shell processes are descendants of init and commands run from them are child processes. Environment: Each process inherits a set of environmental variables from it’s parent process.

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103.5 – Process Attributes and Concepts
The kernel starts the first process: init which has PID 1 Lifetime: Each process starts when it’s command is executed, and lives till it dies or is killed. Process ID (PID): Every process has a unique number assigned to it when it is started. User ID and Group ID: Processes have the privileges associated with the user / group who started them. Parent processes (PPID): Shell processes are descendants of init and commands run from them are child processes. Environment: Each process inherits a set of environmental variables from it’s parent process. Current Working Directory: Each process starts with a default directory.

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103.5 – Process Monitoring
Processes have to be monitored so as to check their health and use of system resources.

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103.5 – Process Monitoring
Processes have to be monitored so as to check their health and use of system resources. • ps
$ ps aux |grep ssh root 866 0.0 0.3 2676 1268 ? S 07:56 0:00 /usr/sbin/sshd

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103.5 – Process Monitoring
Processes have to be monitored so as to check their health and use of system resources. • ps
$ ps aux |grep ssh root 866 0.0 0.3 2676 1268 ? S 07:56 0:00 /usr/sbin/sshd

• pstree
$ pstree init-+-alarmd |-apmd |-kdeinit-+-autorun | |-kdeinit---emacs

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103.5 – Process Monitoring
Processes have to be monitored so as to check their health and use of system resources. • ps
$ ps aux |grep ssh root 866 0.0 0.3 2676 1268 ? S 07:56 0:00 /usr/sbin/sshd

• pstree
$ pstree init-+-alarmd |-apmd |-kdeinit-+-autorun | |-kdeinit---emacs

• top
$ top PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM 1792 geoffrey 11 0 8796 8796 7932 S 0.3 2.2 1590 root 14 0 57512 13M 2572 R 0.1 3.6 2857 geoffrey 14 0 1056 1056 836 R 0.1 0.2 TIME 0:01 0:41 0:01 COMMAND kdeinit X top

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103.5 – Process Management
Normally the kernel automatically manages processes. However sometimes processes have to be started, stopped, restarted and killed.

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103.5 – Process Management
Normally the kernel automatically manages processes. However sometimes processes have to be started, stopped, restarted and killed. • Starting a process:
# /usr/sbin/httpd ps aux |grep httpd root 2987 0.0 apache 3003 0.0

0.4 0.4

4512 1584 ? 4656 1672 ?

/usr/sbin/httpd /usr/sbin/httpd

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103.5 – Process Management
Normally the kernel automatically manages processes. However sometimes processes have to be started, stopped, restarted and killed. • Starting a process:
# /usr/sbin/httpd ps aux |grep httpd root 2987 0.0 apache 3003 0.0

0.4 0.4

4512 1584 ? 4656 1672 ?

/usr/sbin/httpd /usr/sbin/httpd

• Occasionally processes die and have to be restarted.

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103.5 – Process Management
Normally the kernel automatically manages processes. However sometimes processes have to be started, stopped, restarted and killed. • Starting a process:
# /usr/sbin/httpd ps aux |grep httpd root 2987 0.0 apache 3003 0.0

0.4 0.4

4512 1584 ? 4656 1672 ?

/usr/sbin/httpd /usr/sbin/httpd

• Occasionally processes die and have to be restarted. • Processes may go beserk and have to be killed.
# kill -9 1234

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103.5 – Process Management
Normally the kernel automatically manages processes. However sometimes processes have to be started, stopped, restarted and killed. • Starting a process:
# /usr/sbin/httpd ps aux |grep httpd root 2987 0.0 apache 3003 0.0

0.4 0.4

4512 1584 ? 4656 1672 ?

/usr/sbin/httpd /usr/sbin/httpd

• Occasionally processes die and have to be restarted. • Processes may go beserk and have to be killed.
# kill -9 1234

• After configuration changes processes may have to be restarted so as to re-read their configuration files.
# service xinetd restart Stopping xinetd: Starting xinetd: [ [ OK OK ] ]

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103.5 – What is multitasking?
Multitasking is used to describe the situation where one processor (CPU) is used to perform multiple tasks concurrently. • Only one task or program is executing instructions on the CPU. • The CPU must be regularly switched between each program and others. • This process is known as a task switch. • At each task switch the Linux kernel must save the context of the CPU. • The operating system uses the saved context when it switches back to the task the next time it gets some CPU time scheduled to it.

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103.5 – Task Scheduling
The total number of slices, when, how often and for how long the CPU is switched is determined by the multitasking algorithm and is handled by a software component within the kernel know as the task scheduler. There are three basic types of task scheduling: Nonpreemptive: A task must relinquish the CPU before a task switch occurs. Preemptive: The kernel takes away the CPU from a task without notice. Realtime: Tasks are prioritised. High priority tasks must complete before a task switch.

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103.5 – What is a Process?
The term process is a fundamental abstraction: Two of the more traditional definitions of a process are: “A program in execution.” “A single program running in its own virtual address space” In practice, a process is simply an executable that has been loaded into memory and is either running or ready to run on the system.

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103.5 – Process types
Processes under Linux fall into three basic categories: Interactive Process: An interactive process is a process initiated from (and controlled by) a shell. Interactive processes may be in foreground or background. (Example: ls, ls &) Batch Process: A batch process is a process that is not associated with a terminal but is submitted to a queue to be executed sequentially. (Example slocate started by cron) Daemon Process: A daemon process is a process that runs in the background until it’s required. This kind of processes is usually initiated when Linux boots. (Example: inetd, lpd)

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103.5 – Elements associated with a process
For each process running on the system, the kernel needs to keep a list of resources used by that process. Some of these resources include: • tty association (tty struct) • file system (eg current directory & open files) (fs struct, files struct) • memory allocation (mm struct) • Signals received (signal struct)

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103.5 – Process States
At any given point in time, a process is in one of 5 states: TASK RUNNING: The process is either executing on the CPU or waiting to be executed. TASK INTERRUPTIBLE: The process is sleeping until something becomes true. Raising a hardware interrupt, waiting for a system resource etc are examples of a condition that might wake the process up. If a signal is received by the process (eg KILL -HUP) the process will also be woken up. TASK UNINTERRUPTIBLE: Like the previous state except that delivering a signal will not wake the process up. TASK STOPPED: Process execution has stopped. A process enters this state after receiving a SIGSTOP signal. A debugger may use this to step through a program. TASK ZOMBIE: Process execution has stopped but the kernel has not yet ?cleaned up? the resources allocated to the process.

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103.5 – The Process Family Tree
Every process (with the sole exception of the kernel), must be created by another process. The terms parent, child and sibling (or sometimes father, son and brother in a patriarchal sense) are used to describe the relationships between processes. As an example consider the following line executed from the bash prompt: [andy@Node4] andy]$ ls & df -h & The following relationships are true: • The ls and df processes are both siblings to each other. • The bash process (ie the shell) is the parent to both ls and df. • The ls process has bash as its parent. • The df process has bash as its parent.

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103.5 – The Kernel is at the Top of the Family Tree
• When linux boots, the first thing it does is load the kernel into memory and start executing itself. • One of the first things it does once execution starts, is to spawn a process called init, which in turn spawns other processes. • In this sense, the kernel is at the top of the family tree, with only one child process called init. • Init in turn has many children and probably many grandchildren. Kernel --> Init --> all other processes --> even more processes -->

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103.5 – Process IDs
In order for the kernel to keep track of all processes and their descendants, a process ID is assigned to every process running on the system. Process IDs are just numbers and run from 0 to 32767. The number 32767 is the largest signed integer available with a sixteen bit word size and is used to maintain backward compatibility with 16 bit architectures. There are two PIDs (process IDs) that are always the same: • kernel PID is always 0 • init PID is always 1 Each time a new process is created, a new PID is allocated and is equal to the last PID issued plus one. Once the last PID is reached, the PID wraps back around to zero and the next available PID is used (note that 0 and 1 will never be available). This scheme is a little like the assignment of telephone numbers: When a telephone service is disconnected, rather than just assigning the old telephone number to a new subscriber, the old number remains out of use until all other numbers have been used up. This saves “wrong numbers” to the new subscriber from callers who have not yet realised that the old number is no longer connected to the person they were trying to reach. In a similar vein, the kernel does

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this to minimise “wrong numbers” from other processes who have not yet worked out that their intended process no longer exists. This is especially true for Interprocess Communication (IPC) which uses the PID to identify a target process.

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103.5 – Displaying Process Information
There are two utilities used to display the state of running processes: • ps • top The ps command is used to display a “snapshot” of all processes running on the system at the time the ps command was executed. The top command is used to display a real-time display of all processes running on the system. Top can also be used in interactive mode to kill or renice (change priority) of a process.

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103.5 – Process Monitoring—ps
The ps command has a huge number of switches. The switches can be subdivided into two main groups: • Process selection (which processes to display) • Output control (how and what output should be displayed) usage: ps [options]

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103.5 – ps options
The switches that need to be known for the purposes of LPIC are as follows: a Display processes for all users txx Display processes within controlling terminal txx u Display user information for the process l Display in long format with detailed information s Display signal information m Display memory information x Display processes without a controlling terminal S Display CPU time and page faults of child processes -C cmd Search for instances of command cmd. -f Forest mode shows process family trees. -w Wide format

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103.5 – ps options
$ ps ? ERROR: Garbage option. ********* simple selection ********* ********* selection by list ********* -A all processes -C by command name -N negate selection -G by real group ID (supports names) -a all w/ tty except session leaders -U by real user ID (supports names) -d all except session leaders -g by session leader OR by group name -e all processes -p by process ID T all processes on this terminal -s processes in the sessions given a all w/ tty, including other users -t by tty g all, even group leaders! -u by effective user ID (supports names) r only running processes U processes for specified users x processes w/o controlling ttys t by tty *********** output format ********** *********** long options *********** -o,o user-defined -f full --Group --User --pid --cols -j,j job control s signal --group --user --sid --rows -O,O preloaded -o v virtual memory --cumulative --format --deselect -l,l long u user-oriented --sort --tty --forest --version X registers --heading --no-heading ********* misc options ********* -V,V show version L list format codes f ASCII art forest S children in sum -y change -l format -m,m show threads -n,N set namelist file c true command name n numeric WCHAN,UID -w,w wide output e show environment -H process hierarchy

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103.5 – ps field names & their meanings
USER The user who started the process PID The process ID %CPU Shows the cputime / realtime percentage. %MEM The fraction of RSS divided by the total size of RAM VSZ Size of virtual memory used by the process RSS Resident set size (Data & Text segments only) in Kb TTY The TTY associated with this process STAT The current status (DRSTZW¡NL) (details next slide) TIME CPU time in MINS:SECS COMMAND The full command line used to start the process

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103.5 – ps Status Field
$ ps aux USER PID %CPU %MEM root 1 0.0 0.0 VSZ 1304 RSS TTY 72 ? STAT START S Mar21 TIME COMMAND 0:19 init

D uninterruptible sleep (usually IO) R runnable (on run queue) S sleeping T traced or stopped Z a defunct (“zombie”) process W has no resident pages < high-priority process N low-priority task L has pages locked into memory (for real-time and custom IO)

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103.5 – ps Status Field
$ ps aux USER root root root root root root root root root root root rpc rpcuser ntp root root ..... andy root andy PID %CPU %MEM 1 0.0 0.2 2 0.0 0.0 3 0.0 0.0 5 0.0 0.0 6 0.0 0.0 7 0.0 0.0 8 0.0 0.0 9 0.0 0.0 103 0.0 0.0 474 0.0 0.2 479 0.0 0.4 497 0.0 0.2 525 0.0 0.3 735 0.0 0.8 759 0.0 0.3 763 0.0 0.3 1176 1343 1664 0.0 0.0 0.0 0.5 0.7 0.3 VSZ RSS TTY 1384 516 ? 0 0? 0 0? 0 0? 0 0? 0 0? 0 0? 0 0? 0 0? 1444 620 ? 2080 1152 ? 1632 708 ? 1624 796 ? 2088 2080 ? 5784 856 ? 5784 856 ? 2620 1508 pts/0 3000 1816 tty1 2824 924 pts/1 STAT S SW SW SW SW SW SW SW< SW S S S S SL S S S S R START 11:43 11:43 11:43 11:43 11:43 11:43 11:43 11:43 11:44 11:44 11:44 11:44 11:44 11:44 11:44 11:44 11:46 15:21 21:52 TIME 0:04 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 COMMAND init [5] [keventd] [kapm-idled] [kswapd] [kreclaimd] [bdflush] [kupdated] [mdrecoveryd] [kjournald] syslogd -m 0 klogd -2 portmap rpc.statd ntpd -U ntp ypbind ypbind

0:00 bash 0:00 ssh node10 0:00 ps -aux

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103.5 – Process Monitoring—$ pstree
$ pstree init-+-anacron---run-parts---cfengine |-5*[apache-ssl] |-atd |-bash---startx---xinit-+-X | ‘-enlightenment-+-E-Clock.epplet | |-E-Cpu.epplet | |-Emix.epplet | |-Eterm---bash-+-abiword---AbiWord | | ‘-mozilla-bin---moz | |-Eterm---bash---bash | |-Eterm---bash | |-Eterm---bash---gv---gs | |-Eterm---bash---mutt | |-Eterm---bash---emacs-+-ispell | | ‘-xdvi---gs |-Eterm---bash---pstree | | ‘-Eterm---bash---man---pager |-cron |-gcache |-6*[getty] |-inetd---nmbd |-junkbuster

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103.5 – $ pstree options
Three commonly used options for pstree: -a Show command line arguments. |-xfs -daemon |-xfstt --port 7101 --daemon --user nobody ‘-zope-z2 /usr/sbin/zope-z2 ‘-python /usr/sbin/zope-z2 -n Sort processes with the same ancestor by PID -p Show PIDs. init(1)-+-anacron(27095)---run-parts(27755)---cfengine(27765) |-apache-ssl(27188) |-apache-ssl(27189)

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103.5 – Process Monitoring—$ pstree

41

103.5 – Process Monitoring—$ top
The ”top” command provides a continuously updated, real-time look at process activity, memory and swap file usage plus CPU activity. It also shows what processes are running and by whom.

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103.5 – Process Monitoring—$ top
The ”top” command provides a continuously updated, real-time look at process activity, memory and swap file usage plus CPU activity. It also shows what processes are running and by whom. • Its primary use is as an administration and system information tool. It provides an extension to the functionality of the ”ps” command.

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103.5 – Process Monitoring—$ top
The ”top” command provides a continuously updated, real-time look at process activity, memory and swap file usage plus CPU activity. It also shows what processes are running and by whom. • Its primary use is as an administration and system information tool. It provides an extension to the functionality of the ”ps” command. • It makes it easy to find an errand process and ”kill” that process. It also has an interactive interface whereby options can be passed while the command is actually running. All in all, a very useful tool.

42-b

103.5 – $ top ←
9:16am up 13 days, 8:05, 8 users, load average: 0.05, 0.05, 0.00 86 processes: 84 sleeping, 1 running, 1 zombie, 0 stopped CPU states: 2.3% user, 0.7% system, 0.0% nice, 96.8% idle Mem: 900236K av, 546472K used, 353764K free, 0K shrd, 37552K buff 190764K cached Swap: 329324K av, 34784K used, 294540K free PID 10281 12547 10284 12173 12543 1 2 USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND root 16 -10 97952 6452 1584 S < 0 3.9 0.7 56:57 X geoff 16 0 1728 1728 764 R 0 0.9 0.1 0:01 top geoff 12 0 3012 2568 1352 S 0 0.7 0.2 50:49 enlight geoff 10 0 9340 9340 3768 S 0 0.3 1.0 0:11 emacs geoff 9 0 3328 3328 2072 S 0 0.1 0.3 0:00 Eterm root 9 0 116 72 52 S 0 0.0 0.0 0:19 init root 9 0 0 0 0 SW 0 0.0 0.0 0:01 keventd

43

103.5 – top’s command line options
Note: dashes not required. -b Batch mode. Useful for sending output from top to other programs or to a file. Output is plain text. -d Delay between screen updates. (default 5 seconds) -i

44

103.5 – top’s upper screen
9:16am up 13 days, 8:05, 8 users, load average: 0.05, 0.05, 0.00 86 processes: 84 sleeping, 1 running, 1 zombie, 0 stopped CPU states: 2.3% user, 0.7% system, 0.0% nice, 96.8% idle Mem: 900236K av, 546472K used, 353764K free, 0K shrd, 37552K buff 190764K cached Swap: 329324K av, 34784K used, 294540K free • The current system time: • The ”up time” of the system: • How many users are logged in. • The ”load average” : the average number of processes ready to run over the last 1,5 and 15 minutes • ”CPU States” shows the percentage of CPU time spent in usermode, system mode and at idle. • ”MEM” shows a complete set of statistics on current memory usage. • ”SWAP” gives us the same details as ”MEM” but for the swap space.

45

103.5 – top’s lower screen
PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 10281 root 16 -10 97952 6452 1584 S < 0 3.9 0.7 56:57 X 12547 geoff 16 0 1728 1728 764 R 0 0.9 0.1 0:01 top PID The process ID of each task. USER The user name of the task’s owner. PRI The priority of the task. NI The nice value of the task. Negative nice values are higher priority. SIZE The size of the task’s code plus data plus stack space, in kilobytes, is shown here. RSS The total amount of physical memory used by the task,in kilobytes, is shown here. For ELF processes used library pages are counted here, for a.out processes not. SHARE The amount of shared memory used by the task is shown in this column. ctd. . .

46

103.5 – top’s lower screen
PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 10281 root 16 -10 97952 6452 1584 S < 0 3.9 0.7 56:57 X 12547 geoff 16 0 1728 1728 764 R 0 0.9 0.1 0:01 top STAT The state of the task is shown here. The state is either S sleeping D uninterruptible sleep R running Z zombies T stopped or trace These states are modified by trailing < for a process with negative nice value, N for a process with positive nice value, W for a swapped out process (this does not work correctly for kernel processes). %CPU The task’s share of the CPU time since the last screen update, expressed as a percentage of total CPU time per processor. %MEM The task’s share of the physical memory.

47

103.5 – top: selected interactive commands
ˆL Redraw the screen f|F Add and remove fields h|? Displays a help screen S Toggle cumulative mode I Toggle between Irix and Solaris views (SMP-only) k Kill a task (with any signal) r Renice a task T Sort by time / cumulative time s Set the delay in seconds between updates q Quit

48

103.5 – top’s interactive commands
space Update display ˆL Redraw the screen f|F Add and remove fields o|O Change order of displayed fields h|? Displays a help screen S Toggle cumulative mode i Toggle display of idle processes I Toggle between Irix and Solaris views (SMP-only) c Toggle display of command name/line l Toggle display of load average m Toggle display of memory information t Toggle display of summary information

49

k Kill a task (with any signal) r Renice a task N Sort by pid (Numerically) A Sort by age P Sort by CPU usage M Sort by resident memory usage T Sort by time / cumulative time u Show only a specific user n|# Set the number of process to show s Set the delay in seconds between updates W Write configuration file /.toprc q Quit

50

103.5 – ˜/.toprc
$ cat toprc ← AbcDgHIjklMnoTP|qrsuzyV{EFWx 2

51

103.5 – Killing Processes

52

103.5 – Job Control
There are three commands and a pretzel used for job control. • jobs • fg • bg •& They are bash built-ins: $ type jobs fg bg ← jobs is a shell builtin fg is a shell builtin bg is a shell builtin For more information, see the Job Control section of man bash.

53

103.5 – &— Direct the shell to execute a command in the background.
Example: $ xeyes ← Notice the xeyes process is started in the foreground and you have no prompt. The user is locked out of further interaction with the shell until a process is stopped, terminated or completed. Now start the xeyes process in the background. $ xeyes & ← [1] 1650 $ Two numbers are listed and the prompt is now also displayed waiting for another command.

54

103.5 – Job Control
$ xeyes & ← [1] 1650 $ • The [1] is the programs job id, a unique number for the shell starting from 1. • The 1650 is the process id (pid), which identifies the process across the entire system. • Either of these numbers can be used to interact with the program through bash.

55

103.5 – Background Processing
The best candidates for background processing are programs that do not require user input, as these programs will keep on waiting until input is provided. Programs that send their results to standard output (The screen), will do so even if running in the background. If the user is performing another operation, the results may be difficult to interpret. The output from these processes can be redirected to a file. $ wc bigfile > bigfile.wc & ← [1] 1654 $

56

103.5 – The jobs command
$ jobs ← : Lists all commands stopped, or running in the background. Options : -l List pid Example : Start some processes in the background and suspend a foreground process. $ jobs ← [1]+ Stopped [2]- Running $ less job_control.txt xeyes &

57

103.5 – The fg command
$ fg ← : Shell built-in used to force a suspended or background process to continue running in the foreground. Example : Use the ’jobs’ command to find job id. $ jobs ← [1]+ Stopped [2]- Running $ Use fg to bring xeyes to foreground. $ fg 2 ← xeyes A % used with the job id is equivalent to fg 2. $ %2 ← xeyes less job_control.txt xeyes &

58

103.5 – The fg command
A job can also be referred to by a string that uniquely identifies the beginning of the command line used to start a job. A ’%’ can also be used with a unique string. $ fg x ← xeyes or $ %x ← xeyes If fg is issued without any argument, the job with the ’+’ in the job list is brought to the foreground. $ fg ← xeyes

59

103.5 – The bg command
$ bg ← : Used to force a suspended process to continue running in the background. Example : Use the ’jobs’ command to find job id. $ jobs ← [1]- Stopped [2]+ Stopped Running [3] $ find -name myfile >myfile.found less job_control.txt xeyes & (wd: /)

Job 1 shows the ’find’ command was started in the foreground and then suspended.To start ’find’ in the background, use the ’bg’ command or ’%’. Example : $ bg 1 ← or $ bg f ← or $ %1 & ← or $ %f & ←

60

103.6 – Modify process execution priorities [2]
103.6 – Objective
Candidate should be able to manage process execution priorities. Tasks include running a program with higher or lower priority, determining the priority of a process and changing the priority of a running process.

61

103.7 – Search text files using regular expressions [3]
103.7 – Objective
The candidate should be able to manipulate files and text data using regular expressions. This objective includes creating simple regular expressions containing several notational elements. It also includes using regular expression tools to perform searches through a filesystem or file content.

62

103.8 – Perform basic file editing operations using vi [2]
103.8 – Objective
Candidate must be able to edit text files using vi. This objective includes vi navigation, basic vi nodes, inserting, editing, deleting, copying, and finding text.

63

104 – (2.4) Devices, Linux Filesystems & FHS [21]
1. Create partitions and filesystems [3] 2. Maintain the integrity of filesystems [5] 3. Control mounting and unmounting filesystems [3] 4. Managing disk quota [1] 5. Use file permissions to control access to files [3] 6. Manage file ownership [2] 7. Create and change hard and symbolic links [2] 8. Find system files and place files in the correct location [2]

64

104.1 – Create partitions and filesystems [3]
104.1 – Objective
Candidates should be able to configure disk partitions and then create filesystems on media such as hard disks. This objective includes using various mkfs commands to set up partitions to various filesystems, including ext2, ext3, reiserfs, vfat, and xfs.

104.1 – Key files, terms, and utilities include:
fdisk mkfs

104.1 – Resources
TBA

65

104.1 – devices—major and minor numbers

66

104.1 – devices—major and minor numbers
• All devices have a major and a minor number, e.g. floppy disks have the major number of 2 and the first floppy disk has a minor number of 0.

66-a

104.1 – devices—major and minor numbers
• All devices have a major and a minor number, e.g. floppy disks have the major number of 2 and the first floppy disk has a minor number of 0. • All devices are represented by device nodes in /dev/

66-b

104.1 – devices—major and minor numbers
• All devices have a major and a minor number, e.g. floppy disks have the major number of 2 and the first floppy disk has a minor number of 0. • All devices are represented by device nodes in /dev/ • Device nodes may be made thus: # mknod -b /dev/fd0 2 0 ←

66-c

104.1 – devices—major and minor numbers
• All devices have a major and a minor number, e.g. floppy disks have the major number of 2 and the first floppy disk has a minor number of 0. • All devices are represented by device nodes in /dev/ • Device nodes may be made thus: # mknod -b /dev/fd0 2 0 ← • Should you inadvertently loose your device nodes a new set can be generated by running the utility /dev/MAKEDEV

66-d

104.1 – devices—major and minor numbers
• All devices have a major and a minor number, e.g. floppy disks have the major number of 2 and the first floppy disk has a minor number of 0. • All devices are represented by device nodes in /dev/ • Device nodes may be made thus: # mknod -b /dev/fd0 2 0 ← • Should you inadvertently loose your device nodes a new set can be generated by running the utility /dev/MAKEDEV • Access to devices may be modified by changing the permissions to the device node. However, there is usually a better way.

66-e

104.1 – block devices
Block devices are generally random access rotating memory but may use other technologies. • ide hard disk—/dev/hdc • scsi hard disk—/dev/sdb • scsi cdrom—/dev/sr2 • ide zip disk—/dev/hdd • floppy disk—/dev/fd5 • ide cdrom disk—/dev/hdc • scsi cd-rw disk—/dev/sr4

67

104.1 – disk partitions
On i386 systems disks may be sliced up into to 15 partitions.

68

104.1 – disk partitions
On i386 systems disks may be sliced up into to 15 partitions. • The disk must have at least 1 primary partition. /dev/hda1

68-a

104.1 – disk partitions
On i386 systems disks may be sliced up into to 15 partitions. • The disk must have at least 1 primary partition. /dev/hda1 • There may be up to 4 primary partitions. /dev/hda1 /dev/hda2 /dev/hda3 /dev/hda4 (primary) (primary) (primary) (primary)

68-b

104.1 – disk partitions
On i386 systems disks may be sliced up into to 15 partitions. • The disk must have at least 1 primary partition. /dev/hda1 • There may be up to 4 primary partitions. /dev/hda1 /dev/hda2 /dev/hda3 /dev/hda4 (primary) (primary) (primary) (primary)

• One of the primary partitions may be made into an extended partition.

68-c

104.1 – disk partitions
On i386 systems disks may be sliced up into to 15 partitions. • The disk must have at least 1 primary partition. /dev/hda1 • There may be up to 4 primary partitions. /dev/hda1 /dev/hda2 /dev/hda3 /dev/hda4 (primary) (primary) (primary) (primary)

• One of the primary partitions may be made into an extended partition. • The one extended partition must hold between 1 and 12 logical partitions. /dev/hda1 /dev/hda2 /dev/hda5 /dev/hda6 (primary) (extended) (logical) (logical)

68-d

104.1 – fdisk disk partitioning tool
# fdisk ← Usage: fdisk [-l] [-b SSZ] E.g.: fdisk /dev/hda (for or: fdisk /dev/sdc (for or: fdisk /dev/eda (for or: fdisk /dev/rd/c0d0 or: fdisk /dev/ida/c0d0 ... # [-u] device the first IDE disk) the third SCSI disk) the first PS/2 ESDI drive) (for RAID devices) (for RAID devices)

69

104.1 – fdisk disk partitioning tool
# fdisk ← Usage: fdisk [-l] [-b SSZ] E.g.: fdisk /dev/hda (for or: fdisk /dev/sdc (for or: fdisk /dev/eda (for or: fdisk /dev/rd/c0d0 or: fdisk /dev/ida/c0d0 ... # -b sectorsize old kernels only -l list the partition table only -u sectors not cylinders -s print size in blocks [-u] device the first IDE disk) the third SCSI disk) the first PS/2 ESDI drive) (for RAID devices) (for RAID devices)

69-a

104.1 – fdisk
# fdisk /dev/hda ← The number of cylinders for this disk is set to 3648. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): _

70

104.1 – fdisk menu
Command (m for help): m ← Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition’s system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only)

71

104.1 – fdisk print the partition table
Command (m for help): p ← Disk /dev/hda: 255 heads, 63 sectors, 3648 cylinders Units = cylinders of 16065 * 512 bytes Device Boot /dev/hda1 * /dev/hda2 /dev/hda5 /dev/hda6 /dev/hda7 /dev/hda8 Start 1 769 769 781 905 2364 End 768 3648 780 904 2363 2485 Blocks 6168928+ 23133600 96358+ 995998+ 11719386 979933+ Id c 5 83 82 83 83 System Win95 FAT32 (LBA) Extended Linux Linux swap Linux Linux

Command (m for help): _

72

104.1 – fdisk exercise on a floppy

Warning it makes no sense to use fdisk on a floppy.
# fdisk /dev/fd0 Command (m for help): p Disk /dev/fd0: 2 heads, 18 sectors, 80 cylinders Units = cylinders of 36 * 512 bytes Device Boot /dev/fd0p1 /dev/fd0p2 /dev/fd0p3 /dev/fd0p5 /dev/fd0p6 /dev/fd0p7 Start 1 21 26 26 31 71 End 20 25 80 30 70 80 Blocks 351 90 990 81 711 171 Id 1 83 5 83 83 83 System FAT12 Linux Extended Linux Linux Linux

73

104.1 – using sfdisk on a floppy
# sfdisk -f /dev/fd0 Disk /dev/fd0: 80 cylinders, 2 heads, 18 sectors/track Old situation: Units = cylinders of 18432 bytes, blocks of 1024 bytes,counting from 0 Device Boot Start End #cyls #blocks Id System /dev/fd0p1 0+ 19 20351 1 FAT12 /dev/fd0p2 20 24 5 90 83 Linux /dev/fd0p3 25 79 55 990 5 Extended /dev/fd0p4 0 0 0 0 Empty /dev/fd0p5 25+ 29 581 83 Linux /dev/fd0p6 30+ 69 40711 83 Linux /dev/fd0p7 70+ 79 10171 83 Linux Input in the following format; absent fields get a default value. <start> <size> <type [E,S,L,X,hex]> <bootable [-,*]> <c,h,s> <c,h,s> Usually you only need to specify <start>, <size> (and perhaps <type>). /dev/fd0p1 :

74

104.1 – using sfdisk on hda
# sfdisk -f /dev/hda ← Disk /dev/hda: 3648 cylinders, 255 heads, 63 sectors/track Old situation: Units = cylinders 8225280 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/hda1 0+ 767 768- 6168928+ c Win95 FAT32 (LBA) * /dev/hda2 768 3647 2880 23133600 5 Extended /dev/hda3 0 0 0 0 Empty /dev/hda4 0 0 0 0 Empty /dev/hda5 768+ 779 1296358+ 83 Linux /dev/hda6 780+ 903 124995998+ 82 Linux swap /dev/hda7 904+ 2362 1459- 11719386 83 Linux /dev/hda8 2363+ 2484 122979933+ 83 Linux Input in the following format; absent fields get a default value. <start> <size> <type [E,S,L,X,hex]> <bootable [-,*]> <c,h,s> <c,h,s> Usually you only need to specify <start>, <size> (and perhaps <type>). /dev/hda1 : _

75

104.1 – GNU parted—partition table manipulator
# parted /dev/hda ← (parted) help ← check MINOR do a simple check on the filesystem cp [FROM-DEVICE] FROM-MINOR TO-MINOR copy fs to another partition help [COMMAND] prints general help, help on COMMAND mklabel LABEL-TYPE create a new disklabel (part. table) mkfs MINOR FS-TYPE make a fs FS-TYPE on partititon MINOR mkpart PART-TYPE [FS-TYPE] START END make a partition mkpartfs PART-TYPE FS-TYPE START END make a partition with a fs move MINOR START [END] move partition MINOR name MINOR NAME name partition MINOR NAME print display the partition table quit exit program resize MINOR START END resize filesystem on partition MINOR rm MINOR delete partition MINOR select DEVICE choose the device to edit set MINOR FLAG STATE change a flag on partition MINOR (parted)

76

104.1 – GNU parted—partition table manipulator
This utility has similar uses as the commercial utility ”Partition Magic”. It can resize partitions.
(parted) p Disk geometry for /dev/hda: 0.000-28615.781 megabytes Disk label type: msdos Minor Start End Type Filesystem Flags 1 0.031 6024.375 primary FAT boot, lba 2 6024.375 28615.781 extended 5 6024.406 6118.505 logical ext2 6 6118.537 7091.191 logical linux-swap 7 7091.222 18535.935 logical ext2 8 18535.966 19492.932 logical (parted)

77

104.1 – fips.exe—resize FAT partitions

78

104.1 – File System Types
ext2 Linux standard file system (type 83) ext3 New journaling file system reiserfs Journaling file system qnx4 qnx4 file system minix Used by Minux and where space is at a premium iso9660 Standard file system on CDROMs msdos Microsoft FAT16 file system vfat Microsoft FAT32 file system ntfs Microsoft NT file system hfs Apple file system nfs Network File System proc Linux process file system swap Linux swap file system (type 82) smbfs Samba

79

104.1 – mkfs—make filesystem
One the a partition is made and has been given a type it must

80

104.1 – mkswap

81

104.1 –

82

104.1 –

83

104.1 –

84

104.2 – Maintain the integrity of filesystems [5]
104.2 – Objective
Candidates should be able to verify the integrity of filesystems, monitor free space and inodes, and repair simple filesystem problems. This objective includes the commands required to maintain a standard filesystem, as well as the extra data associated with a journaling filesystem.

104.2 – Key files, terms, and utilities include:
du df debugfs fsck e2fsck mke2fs dumpe2fs tune2fs

85

104.2 – du—disk usage

86

104.2 – df—

87

104.2 – fsck—check and repair a Linux file system
• fsck is used to check and optionally repair a one or more Linux file systems. • filesys can be a device name (e.g. /dev/hdc1, /dev/sdb2), a mount point (e.g. /, /usr, /home), or an ext2 label or UUID specifier (e.g. UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root). • The fsck program will try to run filesystems on different physical disk drives in parallel to reduce total amount time to check all of the filesystems. • Options: – -A Walk through the /etc/fstab file and try to check all file systems in one run. This option is typically used from the /etc/rc system initialization file, instead of multiple commands for checking a single file system. – -a Automatically repair the file system without any questions (use this option with caution).

88

104.2 – e2fsck—check a Linux second extended file system
e2fsck is used to check a Linux second extended file system (e2fs). E2fsck also supports ext2 filesystems containing a journal, which are also sometimes known as ext3 filesystems.

89

104.2 – mke2fs—create a Linux second extended file system
mke2fs is used to create a Linux second extended file system on a device (usually a disk partition). device is the special file corresponding to the device (e.g /dev/hdXX). blocks-count is the number of blocks on the device. If omitted, mke2fs automagically figures the file system size. mke2fs [ -c | -l filename ] [ -b block-size ] [ -f fragmentsize ] [ -i bytes-per-inode ] [ -j ] [ -J journaloptions ] [ -N number-of-inodes ] [ -n ] [ -m reservedblocks-percentage ] [ -o creator-os ] [ -O feature[,...] ] [ -q ] [ -r fs-revision-level ] [ -R raid-options ] [ -v ] [ -F ] [ -L volume-label ] [ -M last-mounted-directory ] [ -S ] [ -T filesystem-type ] [ -V ] device [ blocks-count]

90

104.2 – debugfs—ext2 file system debugger
The debugfs program is a file system debugger. It can be used to examine and change the state of an ext2 file system. debugfs is an interactive debugger. It understands a number of commands. cat filespec Dump the contents of the inode filespec to stdout. cd filespec Change the current working directory to filespec. chroot filespec Change the root directory to be the directory file spec. close Close the currently open file system. ? ? ? ? ?

91

104.2 – dumpe2fs—dump filesystem information
dumpe2fs prints the super block and blocks group information for the filesystem present on device.

92

104.2 – tune2fs—adjust tunable filesystem parameters on ext2 fs
tune2fs adjusts tunable filesystem parameters on a Linux second extended filesystem. tune2fs [ -l ] [ -c max-mount-counts ] [ -e errors-behavior ] [ -i interval-between-checks ] [ -j ] [ -J journal options ] [ -m reserved-blocks-percentage ] [ -r reserved blocks-count ] [ -s sparse-super-flag ] [ -u user ] [ -g group ] [ -C mount-count ] [ -L volume-name ] [ -M last mounted-directory ] [ -O [ˆ]feature[,...] ] [ -U UUID ] device

93

104.3 – Control mounting and unmounting filesystems [3]
104.3 – Objective
Candidates should be able to configure the mounting of a filesystem. This objective includes the ability to manually mount and unmount filesystems, configure filesystem mounting on bootup, and configure user mountable removeable filesystems such as tape drives, floppies, and CDs.

104.3 – Key files, terms, and utilities
/etc/fstab mount umount

104.3 – Resources of Interest
Appropriate man pages.

94

104.3 – Linux file system
Unlike MSDOS based operating systems that use named volumes with separate file systems (C: drive, A: drive, etc.) Linux and other unicies have a unified filesystem with volumes “grafted” in to a single tree at various mount points. The mount points are arbitrary. Typical mount points for removable media are as follows: • Floppy disk: device /dev/fd0 mounted at /mnt/floppy • ZIP drive: mounted at /ZIP • CDROM disk: device /dev/hdc mounted at /mnt/cdrom • CD Writer: device /dev/sd2 mounted at /burner • Network drive: mounted at /mnt/nfs/database • NT Server network drive: /mnt/samba-vol

95

104.3 – First Level Directories
$ tree -L 1 ← / |-- backups |-- bin |-- boot |-- boot˜ |-- dev |-- dvd |-- etc |-- home |-- incomming -> /usr/local/incomming/ |-- lib |-- lost+found |-- mnt |--floppy ‘--cdrom |-- proc |-- root |-- sbin |-- tmp |-- usr |-- var ‘-- zip

96

104.3 – The mount Command # mount -t type /dev/device_node /mount_point ←

97

104.3 – The mount Command # mount -t type /dev/device_node /mount_point ←
type The type of file system e.g. vfat or ext2 device node The device node for the appropriate block device e.g. /dev/fd0 mount point The existing directory where the file system will be come accessible. e.g. /mnt/floppy

97-a

104.3 – The mount Command # mount -t type /dev/device_node /mount_point ←
type The type of file system e.g. vfat or ext2 device node The device node for the appropriate block device e.g. /dev/fd0 mount point The existing directory where the file system will be come accessible. e.g. /mnt/floppy

104.3 – mount example
# touch /flb/im_gona_be_hidden ← # ls /flb ← im_gona_be_hidden # mount -t msdos /dev/fd1 /flb ← mount: block device /dev/fd1 is write-protected, read-only # ls /flb ← ecp5-1.c ecp5-4.c ecp5-6.c #

97-b

104.3 – Filesystem Types
# mount -t type ... ext2 Linux standard file system ext3 New journaling file system reiserfs Journaling file system qnx4 qnx I presume minix Used by Minux and where space is a premium iso9660 Standard file system on CDROMs msdos Microsoft FAT16 file system vfat Microsoft FAT32 file system ntfs Microsoft NT file system hfs Apple file system nfs Network File System smbfs Samba
98

104.3 – configuration: /etc/fstab
The file /etc/fstab is a table of static mount information. The mount command references this table. Edit this file to reflect your system.
$ cat /etc/fstab ← # <file system><mount pt><type> /dev/sda1 /dev/sda2 /dev/sda3 /dev/sda4 /dev/sr5 /dev/hdb /dev/fd0 / /tmp /var none /writer /dvd ext2 ext2 ext2 swap iso9660 iso9660 <options> <dump> <pass> 0 0 0 0 1 2 2 0

defaults,errors=remount-ro rw rw sw defaults,ro,user,noauto defaults,ro,user,noauto defaults,user,noauto

00 00 00

/mnt/floppy auto

99

104.3 – Abreviated mount commands
Using entries in the /etc/fstab configuration file mount commands may be abbreviated: • Mount a floppy $ mount /mnt/floppy ← • Mount the DVD: $ mount /dvd ←

100

104.3 – Abreviated mount commands
Using entries in the /etc/fstab configuration file mount commands may be abbreviated: • Mount a floppy $ mount /mnt/floppy ← • Mount the DVD: $ mount /dvd ←

104.3 – Unmounting filesystems umount
• Unmount a floppy $ umount /mnt/floppy ← • Unmount the DVD: $ umount /dvd ←

100-a

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems.

101

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems. • This file is secret kernel business.

101-a

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems. • This file is secret kernel business. • Do *not* edit this file.

101-b

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems. • This file is secret kernel business. • Do *not* edit this file. • Ever.

101-c

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems. • This file is secret kernel business. • Do *not* edit this file. • Ever. $ cat /etc/mtab ← /dev/hda6 / ext2 rw 0 0 none /proc proc rw 0 0 none /dev/pts devpts rw,gid=5,mode=620 0 0 /dev/hda1 /mnt/disk vfat rw 0 0

101-d

104.3 – /etc/mtab
/etc/mtab is a dynamic table of currently mounted file systems. • This file is secret kernel business. • Do *not* edit this file. • Ever. $ cat /etc/mtab ← /dev/hda6 / ext2 rw 0 0 none /proc proc rw 0 0 none /dev/pts devpts rw,gid=5,mode=620 0 0 /dev/hda1 /mnt/disk vfat rw 0 0 $ mount ← /dev/hda6 on / type ext2 (rw) none on /proc type proc (rw) none on /dev/pts type devpts (rw,gid=5,mode=620) /dev/hda1 on /mnt/disk type vfat (rw)

101-e

104.3 – Disk usage—du
$ du ← 24 961136 961164 20 4 968164 ./vmware/win2000 ./vmware/nt4 ./vmware ./.netscape/cache ./.netscape/archive .

102

104.3 – Disk usage—du
$ du ← 24 961136 961164 20 4 968164 ./vmware/win2000 ./vmware/nt4 ./vmware ./.netscape/cache ./.netscape/archive .

104.3 – Disk filesystem usage—df
$ df ← Filesystem 1k-blocks /dev/hda6 3755460 /dev/hda1 2044240 Used Available Use% Mounted on 3041736 522956 86% / 614664 1429576 31% /mnt/disk

102-a

104.4 – Managing disk quota [1]
104.4 – Objective
Candidates should be able to manage disk quotas for users. This objective includes setting up a disk quota for a filesystem, editing, checking, and generating user quota reports.

104.4 – Key files, terms, and utilities include:
See 104-4.tex

103

104.5 – Use file permissions to control access to files [3]
104.5 – Objective
Candidates should be able to control file access through permissions. This objective includes access permissions on regular and special files as well as directories. Also included are access modes such as suid, sgid, and the sticky bit, the use of the group field to grant file access to workgroups, the immutable flag, and the default file creation mode.

104.5 – Key files, terms, and utilities include:
chmod umask chattr

104

104.6 – Manage file ownership [2]
104.6 – Objective
Candidates should be able to control user and group ownership of files. This objective includes the ability to change the user and group owner of a file as well as the default group owner for new files.

104.6 – Key files, terms, and utilities include:
chmod chown chgrp

105

104.7 – Create and change hard and symbolic links [2]
104.7 – Objective
Candidates should be able to create and manage hard and symbolic links to a file. This objective includes the ability to create and identify links, copy files through links, and use linked files to support system administration tasks.

104.7 – Key files, terms, and utilities include:
ln

106

104.7 – ln link
A link is a pseudofile that creates a shortcut to the original file located elsewhere on the filesystem. Symbolic links Hard links

107

104.7 – Linux files and inodes
Creating a file with a command such as: $ cat -n "Hello" > foo 1. An inode number in the superblock is allocated to the file 2. The files inode is populated with information 3. A directory entry (Hard link) is made in a directory file 4. The file’s data is written to a place on the disk pointed to by the inode

108

104.7 – Linux files and inodes
disk directory entry Name: foo Inode: 123456 hard link inode Inode: 123456 Permissions File Type Owner Address on disk etc. yada yada directory file

echo "yada, yada" > foo $ ls −il foo 123456 −rw−r−−r−−

superblock

1 fred user 10 Mar 20 12:35 foo

109

104.7 – The inode information
Some of the information contained in a file’s inode can be displayed with the ls command: $ ls -il foo 2723514 -rw-r--r-2 geoff geoff 16 Mar 22 09:38 /tmp/foo

A more complete view of inode information may be had with stat:
$ stat foo File: "/tmp/foo" Size: 5 Blocks: 2 IO Block: 4096 Regular File Device: 802h/2050d Inode: 2723514 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 1000/geoffrey) Gid: ( 1000/geoffrey) Access: Fri Mar 22 08:25:00 2002 Modify: Fri Mar 22 09:38:19 2002 Change: Fri Mar 22 09:52:26 2002

110

104.7 – Hard links are directory entries
A file may have one or more hard links to it. Additional hard links are made with the ln command: $ ln foo bar $ ls -il foo bar 2723514 -rw-r--r-2723514 -rw-r--r--

2 geoff geoff 2 geoff geoff

5 Mar 22 09:38 bar 5 Mar 22 09:38 foo

• there is only one file on the disk • it has one inode • it has two names (hard links)

111

104.7 – Hard links are directory entries
Disk directory entry Name: foo Inode Inode: 123456 hard link Inode: 123456 directory entry hard link Permissions File Type Owner Address on disk etc. yada yada directory file

Name: bar Inode: 123456

superblock ln foo bar $ ls −il 123456 −rw−r−−r−− 123456 −rw−r−−r−− 2 fred user 10 Mar 20 12:35 bar 2 fred user 10 Mar 20 12:35 foo

112

104.7 – foo a.k.a. bar
$ chmod 640 foo $ ls -il foo bar 2723514 -rw-r----2723514 -rw-r----$ echo " there" >> bar $ head foo bar ==> foo <== Hello there ==> bar <== Hello there $ ls -il foo bar 2723514 -rw-r----2723514 -rw-r-----

2 geoff geoff 2 geoff geoff

5 Mar 22 09:38 bar 5 Mar 22 09:38 foo

12 geoff geoff 12 geoff geoff

5 Mar 22 09:38 bar 5 Mar 22 09:38 foo

113

104.7 – Hard link constraints
• Hard links are confined within the volume: $ ln foo ˜/fred ln: creating hard link ‘/home/geoffrey/fred’ to ‘foo’: Invalid cross-device link • Directories may not have multiple hard links: $ ln /tmp doh ln: ‘/tmp’: hard link not allowed for directory • ln declines to clobber unless forced: $ ln foo bar ln: ‘bar’: File exists $ ln -f foo bar $

114

104.7 – Symbolic links

115

104.7 – A symbolic link is a file that points to another
symbolic link Disk Directory entry Name: foo Inode: 123456 Directory entry Name: baz Inode: 123457 hard link Inode Inode: 123457 Permissions File Type Owner Address on disk etc. hard link Inode Inode: 123456 Permissions File Type Owner Address on disk etc. yada yada superblock foo directory file

ln −s foo baz $ ls −il 123457 lrwxrwxrwx 123456 −rw−r−−r−−

2 fred user 3

Mar 20 12:35 baz −> foo

2 fred user 10 Mar 20 12:35 foo

116

104.7 – Linux files and inodes

117

104.7 – Linux files and inodes

118

104.7 – Linux files and inodes

119

104.8 – Find system files, place files in the correct location [2]
104.8 – Objective
Candidates should be thoroughly familiar with the Filesystem Hierarchy Standard, including typical file locations and directory classifications. This objective includes the ability to find files and commands on a Linux system.

104.8 – Key files, terms, and utilities include:
find locate slocate updatedb whereis which /etc/updatedb.conf

120

104.8 – Subsections of 104.8
• Data Types • The filesystem layout • find • locate, slocate, updatedb and /etc/updatedb.conf • whereis, which and apropos

121

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments:

122

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments: Shareable Data used on multiple hosts across a network—data files, many executables and common configuration files.

122-a

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments: Shareable Data used on multiple hosts across a network—data files, many executables and common configuration files. Non-shareable Files relevant to a paticular host—system logs, etc.

122-b

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments: Shareable Data used on multiple hosts across a network—data files, many executables and common configuration files. Non-shareable Files relevant to a paticular host—system logs, etc. Data modification How data changes.

122-c

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments: Shareable Data used on multiple hosts across a network—data files, many executables and common configuration files. Non-shareable Files relevant to a paticular host—system logs, etc. Data modification How data changes. Variable Data that changes normal frequent processes—log files, user data etc.

122-d

104.8 – Data Types—FHS Classification
Data sharing scope of data used in networked environments: Shareable Data used on multiple hosts across a network—data files, many executables and common configuration files. Non-shareable Files relevant to a paticular host—system logs, etc. Data modification How data changes. Variable Data that changes normal frequent processes—log files, user data etc. Static Data that does not normally change day to day—binary programs and most of /etc

122-e

104.8 – FHS Data Types

Static

Shareable /usr /usr/local /vavr/mail /home

Non-shareable /etc /boot /var/log /proc

Variable

123

104.8 – The Linux Filesystem
$ ./tree -L 2 -d / / |-- bin |-- boot | |-- grub | ‘-- lost+found |-- dev | ‘-- video |-- etc | |-- CORBA | |-- X11 | |-- alchemist | |-- cron.d | |-- cron.daily | |-- cron.hourly |-- cron.monthly |

124

104.8 – The Linux Filesystem
|-| | |-|-| | | | | |-|-|-| | | home |-- geoffrey ‘-- lost+found initrd lib |-- i686 |-- iptables |-- kbd |-- modules ‘-- security lost+found misc mnt |-- cdrom |-- floppy ‘-- hda8

125

104.8 – The Linux Filesystem
|-| |-| | | |-|-|-|-| | | opt ‘-- prenticehall_cyberclassroom proc |-- 1 |-- scsi |-- sys root sbin tmp usr |-- X11R6 |-- apps |-- bin

126

104.8 – The Linux Filesystem
|-| | | | | | var |-- arpwatch |-- cache |-- db |-- lock |-- log |-- mail -> spool/mail

‘-- win |-- Adobe Albums |-- Dell |-- My Documents | ‘-- zip

127

104.8 – The First Level Directories /boot Files for the boot loader.

128

104.8 – The First Level Directories /boot Files for the boot loader. /dev Device files for accessing devices.

128-a

104.8 – The First Level Directories /boot Files for the boot loader. /dev Device files for accessing devices. /etc Configuration files.

128-b

104.8 – The First Level Directories /boot Files for the boot loader. /dev Device files for accessing devices. /etc Configuration files. /home Home directories for system users.

128-c

104.8 – The First Level Directories /boot Files for the boot loader. /dev Device files for accessing devices. /etc Configuration files. /home Home directories for system users. /lib Shared libraries and kernel modules.

128-d

104.8 – The First Level Directories /boot Files for the boot loader. /dev Device files for accessing devices. /etc Configuration files. /home Home directories for system users. /lib Shared libraries and kernel modules. /mnt Mount points for temporary partitions.

128-e

104.8 – The First Level Directories /opt Location for 3rd party applications.

129

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel.

129-a

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel. /root Home for the superuser.

129-b

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel. /root Home for the superuser. /sbin Esential utilities for system administration

129-c

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel. /root Home for the superuser. /sbin Esential utilities for system administration /tmp Storage for temporary files—cleared at boot time.

129-d

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel. /root Home for the superuser. /sbin Esential utilities for system administration /tmp Storage for temporary files—cleared at boot time. /usr Hierarchy of non esential executables etc.

129-e

104.8 – The First Level Directories /opt Location for 3rd party applications. /proc Virtual filesystem created by the kernel. /root Home for the superuser. /sbin Esential utilities for system administration /tmp Storage for temporary files—cleared at boot time. /usr Hierarchy of non esential executables etc. /var Hierarchy of variable data.

129-f

104.8 – The Filesystem partitions
geoffrey@mintie:˜$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 3.2G 2.7G 357M 89% / /dev/sda2 182M 57M 116M 33% /tmp /dev/sda3 273M 89M 170M 35% /var /dev/hda1 99M 21M 72M 23% /boot /dev/hda2 99M 13M 80M 14% /boot˜ /dev/hda3 9.6G 8.6G 624M 94% /home /dev/hda5 14G 7.1G 6.6G 52% /usr/local /dev/hda6 4.8G 1021M 3.5G 22% /var/cache/apt/archives /dev/hda7 4.8G 20k 4.5G 1% /backups /dev/hda8 2.8G 318M 2.3G 12% /var/lib /dev/hdc1 1.9G 1.2G 739M 61% /mnt/hdc1

130

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system.

131

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader.

131-a

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader. /home Home directories for system users.

131-b

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader. /home Home directories for system users. /opt Location for 3rd party applications.

131-c

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader. /home Home directories for system users. /opt Location for 3rd party applications. /tmp Storage for temporary files—cleared at boot time.

131-d

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader. /home Home directories for system users. /opt Location for 3rd party applications. /tmp Storage for temporary files—cleared at boot time. /usr Hierarchy of non esential executables etc.

131-e

104.8 – The Filesystem partitions
/ (root) Small partition containing the files esential for booting the system. /boot Files for the boot loader. /home Home directories for system users. /opt Location for 3rd party applications. /tmp Storage for temporary files—cleared at boot time. /usr Hierarchy of non esential executables etc. /var Hierarchy of variable data.

131-f

104.8 – The root Filesystem: Esentials
/bin /dev /etc /lib /mnt /root /sbin /lib

132

104.8 – The root Filesystem: Esentials
/bin /dev /etc /lib /mnt /root /sbin /lib Also required: /boot and swap

132-a

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86.

133

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance.

133-a

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games.

133-b

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++.

133-c

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++. /usr/lib Shared program libraries. (+perl modules)

133-d

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++. /usr/lib Shared program libraries. (+perl modules) /usr/local Hierarchy for local files not in distribution.

133-e

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++. /usr/lib Shared program libraries. (+perl modules) /usr/local Hierarchy for local files not in distribution. /usr/sbin System administration utilities not essential for emergency system maintenance.

133-f

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++. /usr/lib Shared program libraries. (+perl modules) /usr/local Hierarchy for local files not in distribution. /usr/sbin System administration utilities not essential for emergency system maintenance. /usr/share Hierarchy of data files that are hardware independent. (e.g. documentation)

133-g

104.8 – The /usr Filesystem /usr/X11R6 Files for XFree86. /usr/bin User commands not needed for emergency maintenance. /usr/games Area for console games. /usr/include Header files for C and C++. /usr/lib Shared program libraries. (+perl modules) /usr/local Hierarchy for local files not in distribution. /usr/sbin System administration utilities not essential for emergency system maintenance. /usr/share Hierarchy of data files that are hardware independent. (e.g. documentation) /usr/src Linux source code.
133-h

104.8 – The /var Filesystem /var/account Can be used for process accounting data.

134

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data.

134-a

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data. /var/crash Crash dumps.

134-b

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data. /var/crash Crash dumps. /var/games Console game saves and score data.

134-c

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data. /var/crash Crash dumps. /var/games Console game saves and score data. /var/lock Lock files for various programs.

134-d

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data. /var/crash Crash dumps. /var/games Console game saves and score data. /var/lock Lock files for various programs. /var/log Main repository for system log files.

134-e

104.8 – The /var Filesystem /var/account Can be used for process accounting data. /var/cache Temporary storage of intermaediate data. /var/crash Crash dumps. /var/games Console game saves and score data. /var/lock Lock files for various programs. /var/log Main repository for system log files. /var/mail System mailbox containing mail files for users.

134-f

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs.

135

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs. /var/run Files describing the current state of the system.

135-a

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs. /var/run Files describing the current state of the system. /var/spool Information that is queued for processing. (e.g. print jobs)

135-b

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs. /var/run Files describing the current state of the system. /var/spool Information that is queued for processing. (e.g. print jobs) /var/state Data for applications with multiple instances.

135-c

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs. /var/run Files describing the current state of the system. /var/spool Information that is queued for processing. (e.g. print jobs) /var/state Data for applications with multiple instances. /var/tmp A more persistant version of /tmp.

135-d

104.8 – The /var Filesystem /var/opt Transient srorage for 3rd party programs. /var/run Files describing the current state of the system. /var/spool Information that is queued for processing. (e.g. print jobs) /var/state Data for applications with multiple instances. /var/tmp A more persistant version of /tmp. /var/yp Database files for NIS.

135-e

104.8 –

136

104.8 – find - search for files in a directory hierarchy
The find command is one of the fundamental tools of Unix. It is a tool that is constantly rediscovered as you perform more and more complex operations with it. The man page of this simple tool is 555 lines long.

To find the file foo.txt somewhere: $find / -name foo.txt

137

104.8 – find - basic use
• The most basic use of find is: $find <directory> -name "<mask>" • To find a missing file somewhere in you home directory $ find ˜ -name missing.file where ˜ is shorthand for your home directory.

138

104.8 – find - basic use
• The most basic use of find is: $find <directory> -name "<mask>" • To find a missing file somewhere in you home directory $ find ˜ -name missing.file where ˜ is shorthand for your home directory. • You can also use masks like "*.txt.gz" but you must put it in quotes. — Why do you have to put it in quotes?

138-a

104.8 – find - basic use
• The most basic use of find is: $find <directory> -name "<mask>" • To find a missing file somewhere in you home directory $ find ˜ -name missing.file where ˜ is shorthand for your home directory. • You can also use masks like "*.txt.gz" but you must put it in quotes. — Why do you have to put it in quotes? • When you use an * in a bash command line it is interpreted as a file expansion and it is looked for in the current directory and if it does exist it is substituted before the command is sent to find. If it is not found then your shell may generate an error message (for example csh, I think).

138-b

104.8 – find - basic options
According to the man page ’find - search for files in a directory hierarchy’ This is true but you can also find directories as well, like the filesystems . First we will start with some basic options: -print list the filename (default, never really use it). -exec run a command -ok run a command after prompting for confirmation. -ls list file like ‘ls -dils‘, is a lot of file information.

139

104.8 – find - advanced options
Advanced doing options, I am sure you will use these one day: -prune don’t descend past this directory. -printf print a filename based on format like C printf. -print0 print but end with a null character. -fprintf <fn> print a format string to a filename, (scripting??) -fprint <fn> print filenames to a file. -fls <fn> ls to a file

140

104.8 – find - entry selection by age
Most of these options take a number, +number or -number. A little explanation is required first. -atime 2 Will pick any file accessed two days ago. -atime -2 Will pick any file access more than two days ago -atime +2 Will pick any file accessed in the last day.

141

104.8 – find - entry selection by age
Most of these options take a number, +number or -number. A little explanation is required first. -atime n files on access date -ctime n files on creation date (note chmod mucks this up -mtime n files on modification date -anewer <file> files on access date based on another file. -cnewer<file> files on creation date based on another file. -newer <file> files on modification date based on another file Example: delete all files older than 7 days in the /data directory who have an .A extension.

142

104.8 – find - entry selection by age
Most of these options take a number, +number or -number. A little explanation is required first. -atime n files on access date -ctime n files on creation date (note chmod mucks this up -mtime n files on modification date -anewer <file> files on access date based on another file. -cnewer<file> files on creation date based on another file. -newer <file> files on modification date based on another file Example: delete all files older than 7 days in the /data directory who have an .A extension.

$ find /data -name "*.A" -ctime -7 -exec rm {} \;

142-a

104.8 – find - entry selection by age
• A script may run a command and then ’touch’ a tag file to give a timestamp when it was run. • Assume that the last thing a script does is touch modification.tag in the /parms directory. • Write a command line that lists all details of files modified in the /apps/source/ directory based on this tag file.

143

104.8 – find - entry selection by age
• A script may run a command and then ’touch’ a tag file to give a timestamp when it was run. • Assume that the last thing a script does is touch modification.tag in the /parms directory. • Write a command line that lists all details of files modified in the /apps/source/ directory based on this tag file.

$ find /data -mnewer /parms/modification.tag -ls

143-a

104.8 – find - entry selection by owner and group
One problem with the Unix authentification system, when you delete a userid you end up with magic numbers on a directory listing. It is handy to be able to change the ownership on all files from the exiting staff member to the new person working on those projects. -nouser users numeric id does not have and entry in /etc/passwd -nogroup group numeric id does not have an entry in /etc/group -uid n User by number -user name User by name -gid n Group by number -group name Group by name I recently converted from Redhat to Debian. I installed a new harddisk and mounted the old one as /mnt/old1. I notice that when I do ls -al I get a username of 500 in the directory listing. Change all the occurrences of 500 to the username of ken.

144

104.8 – find - entry selection by owner and group
One problem with the Unix authentification system, when you delete a userid you end up with magic numbers on a directory listing. It is handy to be able to change the ownership on all files from the exiting staff member to the new person working on those projects. -nouser users numeric id does not have and entry in /etc/passwd -nogroup group numeric id does not have an entry in /etc/group -uid n User by number -user name User by name -gid n Group by number -group name Group by name I recently converted from Redhat to Debian. I installed a new harddisk and mounted the old one as /mnt/old1. I notice that when I do ls -al I get a username of 500 in the directory listing. Change all the occurrences of 500 to the username of ken. # find /mnt/old1 -uid 500 -exec chown ken {} \;

144-a

104.8 – find - entry selection by Inode number and links
You have a directory listing, the hard link count is greater than 1. ... lecturers note wait and ask class how we know this .... You have no idea where the other hard link is and you want to locate the other version to see what impact a change may have. -inode n

145

104.8 – find - entry selection by Inode number and links
You have a directory listing, the hard link count is greater than 1. ... lecturers note wait and ask class how we know this .... You have no idea where the other hard link is and you want to locate the other version to see what impact a change may have. -inode n # find -inode ????

145-a

104.8 – find - entry selection by regex and xdev
Advanced options on what entries we select: -iregex Use regex rather than standard file masks. Options on how we go through the directories: -xdev don’t go into other file systems.

146

104.8 – locate, slocate and updatedb
locate is used to find files on the system using a database rather than actually having to search the entire directory tree. $ locate slide.tex ← /home/geoffrey/tafe/adp/bash/slide.tex

147

104.8 – locate, slocate and updatedb
locate is used to find files on the system using a database rather than actually having to search the entire directory tree. $ locate slide.tex ← /home/geoffrey/tafe/adp/bash/slide.tex • updatedb is the command that updates the database.

147-a

104.8 – locate, slocate and updatedb
locate is used to find files on the system using a database rather than actually having to search the entire directory tree. $ locate slide.tex ← /home/geoffrey/tafe/adp/bash/slide.tex • updatedb is the command that updates the database. • The database is kept in /var/lib/locate/locatedb

147-b

104.8 – locate, slocate and updatedb
locate is used to find files on the system using a database rather than actually having to search the entire directory tree. $ locate slide.tex ← /home/geoffrey/tafe/adp/bash/slide.tex • updatedb is the command that updates the database. • The database is kept in /var/lib/locate/locatedb • slocate The Security Enhanced version of the GNU Locate— now replaces all of these. locate and updatedb become a symbolic links to slocate

147-c

104.8 – locate vs. slocate

148

104.8 – locate vs. slocate
• The locate command as now been replaced by slocate and is now a Symbolic link to slocate.

148-a

104.8 – locate vs. slocate
• The locate command as now been replaced by slocate and is now a Symbolic link to slocate. • The updatedp command as now been replaced by slocate and is now a Symbolic link to slocate.

148-b

104.8 – locate vs. slocate
• The locate command as now been replaced by slocate and is now a Symbolic link to slocate. • The updatedp command as now been replaced by slocate and is now a Symbolic link to slocate.
$ ls -l /usr/bin/ |grep locate ← lrwxrwxrwx 1 root root 7 Mar 27 10:44 locate -> slocate* -rwxr-xr-x 1 root root 9228 Nov 5 2000 locate.notslocate* -rwxr-sr-x 1 root slocate 24504 Feb 4 03:57 slocate* lrwxrwxrwx 1 root root 7 Mar 27 10:44 updatedb -> slocate* -rwxr-xr-x 1 root root 5860 Nov 5 2000 updatedb.notslocate*

148-c

104.8 – locate vs. slocate
• The locate command as now been replaced by slocate and is now a Symbolic link to slocate. • The updatedp command as now been replaced by slocate and is now a Symbolic link to slocate.
$ ls -l /usr/bin/ |grep locate ← lrwxrwxrwx 1 root root 7 Mar 27 10:44 locate -> slocate* -rwxr-xr-x 1 root root 9228 Nov 5 2000 locate.notslocate* -rwxr-sr-x 1 root slocate 24504 Feb 4 03:57 slocate* lrwxrwxrwx 1 root root 7 Mar 27 10:44 updatedb -> slocate* -rwxr-xr-x 1 root root 5860 Nov 5 2000 updatedb.notslocate*

• The database is now in /var/lib/slocate/slocatedb • The database is no longer world readable

148-d

104.8 – slocate - Security Enhanced version of the GNU Locate

149

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree.

149-a

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree. • A database of all files on the system is created and is then used by slocate to reveal the files actual location.

149-b

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree. • A database of all files on the system is created and is then used by slocate to reveal the files actual location. • It is important to note that slocate may return a result which is no longer valid since the directory structure may have been modified since the slocate database was last created.

149-c

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree. • A database of all files on the system is created and is then used by slocate to reveal the files actual location. • It is important to note that slocate may return a result which is no longer valid since the directory structure may have been modified since the slocate database was last created. • For example, you create a file called poobar.txt, create the slocate database and then remove poobar.txt.

149-d

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree. • A database of all files on the system is created and is then used by slocate to reveal the files actual location. • It is important to note that slocate may return a result which is no longer valid since the directory structure may have been modified since the slocate database was last created. • For example, you create a file called poobar.txt, create the slocate database and then remove poobar.txt. • Slocate will still return poobar.txt?s original location until the slocate database is recreated.

149-e

104.8 – slocate - Security Enhanced version of the GNU Locate
• Slocate is used to find files on the system without actually having to search the entire directory tree. • A database of all files on the system is created and is then used by slocate to reveal the files actual location. • It is important to note that slocate may return a result which is no longer valid since the directory structure may have been modified since the slocate database was last created. • For example, you create a file called poobar.txt, create the slocate database and then remove poobar.txt. • Slocate will still return poobar.txt?s original location until the slocate database is recreated. • Slocate can be used in two modes: – Search mode:- To locate an actual file within the database – Database creation mode:- To build the database

149-f

104.8 – locate usage
locate [-qi] Options: -q Quiet mode. Suppress error messages. -i Does a case insensitive search. -d Specify a database to use. -r Pass a regular expression instead of a search string. [-d <path>] [-r <regexp>] <search string>...

150

104.8 – locate examples
locate ls $ locate ls ← ... /etc/X11/xkb/symbols/xfree68/ataritt /etc/X11/xkb/symbols/xfree68/amiga /etc/alternatives/tclsh ... locate -r "/ls$" $ locate -r "/ls$" ← /home/geoffrey/tafe/mos/compress/ls /usr/lib/bitchx/help/8_Scripts/ls /bin/ls The above example illustrates the need for a regex option to locate. In the first example there will be lots of hits. In the second there is only one (the actual ls command). As well as searching for a file in the database, locate can also build the search database.

151

104.8 – Database creation with slocate
As well as searching for a file in the database, slocate can also build the search database. -u Create slocate database starting at path /. -U <dir> Create slocate database starting at path < dir >. -c Parse original GNU Locate’s /etc/updatedb.conf -e <dir1...> Exclude directories from the slocate database when using the -u or -U options. -f <fs...> Exclude file system types from the slocate database -l Security level. 0–> security off, 1–> security on -q Quiet mode. Error messages are suppressed. -o <file> Specify the name of the database file to create -v Be verbose

152

104.8 – Database creation with slocate— Examples

153

104.8 – Database creation with slocate— Examples
• Create a database for all directories under /usr and place the resulting database file into slocate.db in andy’s home directory. # slocate -U /usr -o /home/andy/slocate.db ←

153-a

104.8 – Database creation with slocate— Examples
• Create a database for all directories under /usr and place the resulting database file into slocate.db in andy’s home directory. # slocate -U /usr -o /home/andy/slocate.db ←

• Create a database for all directories under /usr, excluding directories under /usr/man and place the resulting database file into slocate.db in andy?s home directory. # slocate -U /usr -e /usr/man -o /home/andy/slocate.db ←

153-b

104.8 – Update slocate database—update
updatedb is simply a link to slocate that implies the -u option. (Excerpt from the man page:- man updatedb)
$ ls -l ‘which updatedb‘ ← lrwxrwxrwx 1 root root 7 Mar 27 10:44 /usr/bin/updatedb -> slocate*

updatedb is typically executed periodically via cron.

154

104.8 – /etc/updatedb.conf

155

104.8 – /etc/updatedb.conf
• The updatedb (or slocate) tool can use a configuration file to decide which directories and file systems are included when the database is created. This file is normally located in /etc/updatedb.conf

155-a

104.8 – /etc/updatedb.conf
• The updatedb (or slocate) tool can use a configuration file to decide which directories and file systems are included when the database is created. This file is normally located in /etc/updatedb.conf • The following is a list of keywords that are recognised by updatedb (slocate) and their equivalent command line options PRUNEFS <fs type1 fs type2...> - Option -f PRUNEPATHS <dir1 dir2 dir3...> - Opion -e

155-b

104.8 – /etc/updatedb.conf
• The updatedb (or slocate) tool can use a configuration file to decide which directories and file systems are included when the database is created. This file is normally located in /etc/updatedb.conf • The following is a list of keywords that are recognised by updatedb (slocate) and their equivalent command line options PRUNEFS <fs type1 fs type2...> - Option -f PRUNEPATHS <dir1 dir2 dir3...> - Opion -e • Example updatedb.conf PRUNEFS="devpts NFS nfs afs proc smbfs autofs auto iso9660" PRUNEPATHS="/tmp /usr/tmp /var/tmp /afs /net? export PRUNEFS export PRUNEPATHS

155-c

104.8 – slocate Exercises
1. Create an slocate database in your home directory including all directories from / down. 2. Using the database created in step 1, locate all files with rm in the filename 3. Using the database created in step 1, locate the executable file rm using a regex. (ie /some/path/rm) 4. Create an slocate database in your home directory include all directories from / down but excluding the /bin directory. 5. Repeat (2) and (3) above. Do you notice anything different ? 6. After backing up your existing /etc/updatedb.conf, say # cp /etc/updatedb.conf /etc/updatedb.conf.orig ← edit /etc/updatedb.conf to perform the same actions as in step (4). 7. When you have finished this exercise restore your original /etc/updatedb.conf.

156

104.8 – whereis

157

104.8 – which

158

104.8 – /etc/updatedb.conf

159

104.8 –

160

106 – (2.6)Boot, Initialization, Shutdown, Runlevels [6]
1. Boot the system [3] 2. Change runlevels and shutdown or reboot system [3]

161

106.1 – Boot the system [3]
106.1 – Objective
Candidates should be able to guide the system through the booting process. This includes giving commands to the boot loader and giving options to the kernel at boot time, and checking the events in the log files.

106.1 – Key files, terms, and utilities include:
dmesg /var/log/messages /etc/conf.modules or /etc/modules.conf

106.1 – Resources
TBA

162

106.2 – Change runlevels and shutdown or reboot system [3]
106.2 – Objective
Candidates should be able to manage the runlevel of the system. This objective includes changing to single user mode, shutdown or rebooting the system. Candidates should be able to alert users before switching runlevel, and properly terminate processes. This objective also includes setting the default runlevel.

106.2 – Key files, terms, and utilities include:
shutdown init /etc/inittab

106.2 – Resources
TBA

163

106.2 –

164

106.2 –
•a

164-a

106.2 –
•a •b

164-b

106.2 –
•a •b •c

164-c

106.2 –
•a •b •c

•d

164-d

106.2 –
•a •b •c

•d •e

164-e

108 – (1.8) Documentation [8]
1. Use and manage local system documentation [5] 2. Find Linux documentation on the Internet [2] 3. Write System Documentation [1] 4. Provide User Support [1] 5. Notify users on system-related issues [1]

165

108.1 – Use and manage local system documentation [5]
108.1 – Objective
Candidates should be able to use and administer the man facility and the material in /usr/share/doc/. This objective includes finding relevant man pages, searching man page sections, finding commands and man pages related to them, and configuring access to man sources and the man system. It also includes using system documentation stored in

108.1 – Key files, terms, and utilities include:
man apropos whatis MANPATH

108.1 – Resources
TBA

166

108.2 – Find Linux documentation on the Internet [2]
108.2 – Objective
Candidates should be able to find and use Linux documentation. This objective includes using Linux documentation at sources such as the Linux Documentation Project (LDP), vendor and third-party websites, newsgroups, newsgroup archives, and mailing lists.

108.2 – Key files, terms, and utilities include:
not applicable

108.2 – Resources
TBA

167

108.3 – Notify users on system-related issues [1]
108.3 – Objective
Candidates should be able to notify the users about current issues related to the system. This objective includes automating the communication process, e.g. through logon messages.

108.3 – Key files, terms, and utilities include:
/etc/issue /etc/issue.net /etc/motd

108.3 – Resources
TBA

168

108.3 –

169

108.3 –
•a

169-a

108.3 –
•a •s

169-b

108.3 –
•a •s •s

169-c

108.3 –
•a •s •s

•s

169-d

108.3 –
•a •s •s

•s •s

169-e

111 – (2.11) Administrative Tasks [24]
1. Manage users and group accounts and related system files [7] 2. Tune the user environment and system environment variables [4] 3. Configure and use system log files to meet administrative and security needs [3] 4. Automate system administration tasks by scheduling jobs to run in the future [4] 5. Maintain an effective data backup strategy [3] 6. Maintain system time [3]

170

111.1 – Manage user/group accounts, related system files [7]
111.1 – Objective
Candidate should be able to add, remove, suspend and change user accounts. Tasks include to add and remove groups, to change user/group info in passwd/group databases. The objective also includes creating special purpose and limited accounts.

111.1 – Key files, terms, and utilities include:
chageg passwd groupadd groupdel groupmod grpconv grpunconv passwd pwconv pwunconv useradd userdel usermod /etc/passwd /etc/shadow /etc/group /etc/gshadow

111.1 – Resources
Chapter 9 - Managing User Accounts: The Linux System Administrators’ Guide Manpages for useradd usermod userdel groupadd groupmod groupdel useradd passwd chage

171

111.1 – The /etc/passwd file

172

111.1 – useradd - Create a new user or update new user information
# useradd [options] user Options: -c “comment” GCOS field—Users name -d homedir Use homedir as the users home directory -D List and optionally change the default values -m Create and populate the users home directory -s shell Use shell as the users shell

173

111.1 – useradd—examples
• The defaults: # useradd -D GROUP=100 HOME=/home INACTIVE=-1 EXPIRE= SHELL=/bin/bash SKEL=/etc/skel

174

111.1 – useradd—examples
• The defaults: # useradd -D GROUP=100 HOME=/home INACTIVE=-1 EXPIRE= SHELL=/bin/bash SKEL=/etc/skel • Vanilla : # useradd quincy

174-a

111.1 – useradd—examples
• The defaults: # useradd -D GROUP=100 HOME=/home INACTIVE=-1 EXPIRE= SHELL=/bin/bash SKEL=/etc/skel • Vanilla : # useradd quincy • With nuts: # useradd -m -c "Quincy Shnorks" -s zsh quincy

174-b

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd

175

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd • passwd changes passwords for user and group accounts.

175-a

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd • passwd changes passwords for user and group accounts. • A normal user may only change the password for their own account

175-b

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd • passwd changes passwords for user and group accounts. • A normal user may only change the password for their own account • The super user may change the password for any account.

175-c

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd • passwd changes passwords for user and group accounts. • A normal user may only change the password for their own account • The super user may change the password for any account. • The administrator of a group may change the password for the group.

175-d

111.1 – passwd - change user password
• The command: $ which passwd /usr/bin/passwd • passwd changes passwords for user and group accounts. • A normal user may only change the password for their own account • The super user may change the password for any account. • The administrator of a group may change the password for the group. • passwd also changes account information, such as the full name of the user, their login shell, or password expiry dates and intervals.

175-e

111.1 – passwd example
• A user may change their own password: $ passwd Changing password for geoffrey (current) UNIX password: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully

176

111.1 – passwd example
• A user may change their own password: $ passwd Changing password for geoffrey (current) UNIX password: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully • Assuming root privileges: $ su Password:

176-a

111.1 – passwd example
• A user may change their own password: $ passwd Changing password for geoffrey (current) UNIX password: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully • Assuming root privileges: $ su Password: • root may change any passwd: # passwd geoffrey Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully

176-b

111.1 – passwd guidelines
As a general guideline, passwords should consist of 6 to 8 characters including one or more from each of following sets: • Lower case alphabetics • Upper case alphabetics • Digits 0 through 9 • Punctuation marks Examples of secure and memorable passwds: • The Owl and the Pussycat went to sea—TO&tPw2s • I got it—1_got_IT • One and all.— 1_&_All.

177

111.1 –

178

111.1 –
•a

178-a

111.1 –
•a •s

178-b

111.1 –
•a •s •s

178-c

111.1 –
•a •s •s

•s

178-d

111.1 –
•a •s •s

•s •s

178-e

111.2 – Tune user and system environment variables [4]
111.2 – Objective
Candidate should be able to modify global and user profiles. This includes setting environment variables, maintaining skel directories for new user accounts and setting command search path with the proper directory.

111.2 – Key files, terms, and utilities include:
env export set unset /etc/profile /etc/skel

111.2 – Resources
TBA

179

111.3 – Config & use system log files for admin / security [3]
111.3 – Objective
Candidate should be able to configure system logs. This objective includes managing the type and level of information logged, manually scanning log files for notable activity, monitoring log files, arranging for automatic rotation and archiving of logs and tracking down problems noted in logs.

111.3 – Key files, terms, and utilities include:
logrotate /etc/syslog.conf /var/log/* tail -f

111.3 – Resources
TBA

180

111.4 – Automate system admin tasks by job scheduling[4]
111.4 – Objective
Candidate should be able to use cron or anacron to run jobs at regular intervals and to use at to run jobs at a specific time. Task include managing cron and at jobs and configuring user access to cron and at services.

111.4 – Key files, terms, and utilities include:
at atq crontab /etc/anacrontab /etc/at.deny /etc/at.allow /etc/crontab /etc/cron.allow /etc/cron.deny /var/spool/cron/*

111.4 – Resources
TBA

181

111.5 – Maintain an effective data backup strategy [3]
111.5 – Objective
Candidate should be able to plan a backup strategy and backup filesystems automatically to various media. Tasks include dumping a raw device to a file or vice versa, performing partial and manual backups, verifying the integrity of backup files and partially or fully restoring backups.

111.5 – Key files, terms, and utilities include:
cpio dd dump restore tar

111.5 – Resources
TBA

182

111.5 – System Backup Tools
Backing up a system is a vital part of system administration. A good backup strategy involves the following key features:

183

111.5 – System Backup Tools
Backing up a system is a vital part of system administration. A good backup strategy involves the following key features: • Frequent backups (at least daily)

183-a

111.5 – System Backup Tools
Backing up a system is a vital part of system administration. A good backup strategy involves the following key features: • Frequent backups (at least daily) • Backup media is maintained on a rotating basis (eg 28 sets of backup media, rotated daily)

183-b

111.5 – System Backup Tools
Backing up a system is a vital part of system administration. A good backup strategy involves the following key features: • Frequent backups (at least daily) • Backup media is maintained on a rotating basis (eg 28 sets of backup media, rotated daily) • At least one copy of the backup should be kept off-site

183-c

111.5 – System Backup Tools
Backing up a system is a vital part of system administration. A good backup strategy involves the following key features: • Frequent backups (at least daily) • Backup media is maintained on a rotating basis (eg 28 sets of backup media, rotated daily) • At least one copy of the backup should be kept off-site • Backup must have been tested

183-d

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are:

184

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are: • dump / restore

184-a

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are: • dump / restore • rsync

184-b

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are: • dump / restore • rsync • cpio

184-c

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are: • dump / restore • rsync • cpio • ar

184-d

111.5 – Backup Tools
There are many strategies used for system backups. These range from copying a simple file to entire disk partitions to an entire disk. Some tools available under linux are: • dump / restore • rsync • cpio • ar • tar

184-e

111.5 – Dump & Restore
Dump Saves source files or filesystems to backup media (Like the DOS backup utility) Restore Reinstate the backup to files or filesystems (Like the DOS restore utility)

185

111.5 – dump usage
• Dump has 22 options, many of which concern themselves with various tape device setup options (density, tape length, etc.)

186

111.5 – dump usage
• Dump has 22 options, many of which concern themselves with various tape device setup options (density, tape length, etc.) • To dump the /boot directory (in my case a seperate partition), do the following: $ /sbin/dump -0u -f /root/boot.backup /boot ←

186-a

111.5 – dump usage
• Dump has 22 options, many of which concern themselves with various tape device setup options (density, tape length, etc.) • To dump the /boot directory (in my case a seperate partition), do the following: $ /sbin/dump -0u -f /root/boot.backup /boot ← -0 (zero) tells dump to do the entire directory

186-b

111.5 – dump usage
• Dump has 22 options, many of which concern themselves with various tape device setup options (density, tape length, etc.) • To dump the /boot directory (in my case a seperate partition), do the following: $ /sbin/dump -0u -f /root/boot.backup /boot ← -0 (zero) tells dump to do the entire directory -u update the file /etc/dumpdates

186-c

111.5 – dump usage
• Dump has 22 options, many of which concern themselves with various tape device setup options (density, tape length, etc.) • To dump the /boot directory (in my case a seperate partition), do the following: $ /sbin/dump -0u -f /root/boot.backup /boot ← -0 (zero) tells dump to do the entire directory -u update the file /etc/dumpdates -f write the backup to a file

186-d

111.5 – Dump Usage Example:
[root@Node4] root]# df -h /boot Filesystem Size Used Avail Use% Mounted on /dev/hda5 197M 4.1M 183M 3% /boot

187

111.5 – Dump Usage Example:
[root@Node4] root]# df -h /boot Filesystem Size Used Avail Use% Mounted on /dev/hda5 197M 4.1M 183M 3% /boot [root@Node4] root]# dump -0u -f /root/boot.backup /boot DUMP: Date of this level 0 dump: Tue May 7 20:30:36 2002 DUMP: Dumping /dev/hda5 (/boot) to /root/boot.backup DUMP: Label: /boot DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 4224 tape blocks. DUMP: Volume 1 started with block 1 at: Tue May 7 20:30:37 2002 DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] DUMP: Closing /root/boot.backup DUMP: Volume 1 completed at: Tue May 7 20:30:37 2002 DUMP: Volume 1 4210 tape blocks (4.11MB) DUMP: 4210 tape blocks (4.11MB) on 1 volume(s) DUMP: finished in less than a second DUMP: Date of this level 0 dump: Tue May 7 20:30:36 2002 DUMP: Date this dump completed: Tue May 7 20:30:37 2002 DUMP: Average transfer rate: 0 kB/s DUMP: DUMP IS DONE

187-a

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem.

188

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes:

188-a

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes: • Compare - Verify backup file against filesystem

188-b

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes: • Compare - Verify backup file against filesystem • Interactive restore - A small shell like interface to selectively restore files

188-c

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes: • Compare - Verify backup file against filesystem • Interactive restore - A small shell like interface to selectively restore files • Non-interactive restore - Restore files without asking.

188-d

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes: • Compare - Verify backup file against filesystem • Interactive restore - A small shell like interface to selectively restore files • Non-interactive restore - Restore files without asking. • List mode - List contents of a backup file

188-e

111.5 – Restore
Restore takes the data created by the dump command and puts it back to the filesystem. Restore can be used in one of these modes: • Compare - Verify backup file against filesystem • Interactive restore - A small shell like interface to selectively restore files • Non-interactive restore - Restore files without asking. • List mode - List contents of a backup file • Selective restore - Restore files listed on the command line

188-f

111.5 – Restore Usage Example
This is the sequence for a dump—disaster—restore cycle:

189

111.5 – Restore Usage Example
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0u -f /root/boot.backup /boot ←

189-a

111.5 – Restore Usage Example
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0u -f /root/boot.backup /boot ← • Disk dies or some other catastrophe ....

189-b

111.5 – Restore Usage Example
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0u -f /root/boot.backup /boot ← • Disk dies or some other catastrophe .... • Disaster recovery: # # # # mke2fs /dev/hda1 ← mount /dev/hda1 /mnt ← cd /mnt ← restore -r -f /root/boot.backup ←

189-c

111.5 – Restore Usage Example
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0u -f /root/boot.backup /boot ← • Disk dies or some other catastrophe .... • Disaster recovery: # # # # mke2fs /dev/hda1 ← mount /dev/hda1 /mnt ← cd /mnt ← restore -r -f /root/boot.backup ←

(As much as I have faith in the restore command, your not going to see a real live example!!)

189-d

111.5 – Dump and Restore Demonstration
This is the sequence for a dump—disaster—restore cycle:

190

111.5 – Dump and Restore Demonstration
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0 -f /root/boot.backup /boot ←

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111.5 – Dump and Restore Demonstration
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0 -f /root/boot.backup /boot ← • Disk dies or some other catastrophe ....

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111.5 – Dump and Restore Demonstration
This is the sequence for a dump—disaster—restore cycle: • Make a backup: # dump -0 -f /root/boot.backup /boot ← • Disk dies or some other catastrophe .... • Disaster recovery: # cd / ← # restore -r -f /root/boot.backup ←

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111.5 – CPIO - file formats
The archive file can be stored in any of the following formats: • binary (obsolete due to lack of portability) • old ASCII or new ASCII • crc • HPUX binary or HPUX old ASCII • old tar or POSIX.1 tar

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111.5 – CPIO - Copy Out (Create) Usage
cpio -o [options] < filenames_to_archive [> archive file]

• The -o option can be replaced with the long --create option • Output will be sent to stdout unless the -F <file> option is used • The list of files to archive must come from stdin

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111.5 – CPIO - Copy In (Extract) Usage
cpio -i [options] [file_patterns_to_restore] [< archive file]

• The -i option can be replaced with the long --extract option • The input archive will come from stdin unless the -F <file> option is used • If no restore file pattern is given, all files will be restored

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111.5 – CPIO - Copy Pass Usage
cpio -p [options] destination_directory < filenames_to_copy

• The -p option can be replaced with the long --pass-through option • The destination directory is mandatory • The list of files to copy must come from stdin

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111.5 – Options to cpio (for LPIC purposes)

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio)

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode)

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories -E <file> Read file for additional file patterns to restore (copy-in mode)

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories -E <file> Read file for additional file patterns to restore (copy-in mode) -f Copy files that don’t match specified patterns

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories -E <file> Read file for additional file patterns to restore (copy-in mode) -f Copy files that don’t match specified patterns -F <file> Specify an archive filename rather than stdin or stdout

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories -E <file> Read file for additional file patterns to restore (copy-in mode) -f Copy files that don’t match specified patterns -F <file> Specify an archive filename rather than stdin or stdout -0 (zero) Filenames are terminated by null instead of newline (copy-out & copy-pass)

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111.5 – Options to cpio (for LPIC purposes)
-a Reset access time on files (as if they hadn’t been read by cpio) -A Used to append to an archive (in copy-out mode) --block-size N Set the block size to N * 512 bytes -d Create leading directories -E <file> Read file for additional file patterns to restore (copy-in mode) -f Copy files that don’t match specified patterns -F <file> Specify an archive filename rather than stdin or stdout -0 (zero) Filenames are terminated by null instead of newline (copy-out & copy-pass) -r Allows files to be renamed interactively -u Replace files without asking -v Verbosely list files that are processed

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111.5 – CPIO - Examples

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111.5 – CPIO - Examples
• Create a fully qualified list of filenames under /boot: # find /boot > list ←

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111.5 – CPIO - Examples
• Create a fully qualified list of filenames under /boot: # find /boot > list ← • Make an archive of /boot called boot.backup using default bin format: # cpio -o -F boot.backup -v < list ←

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111.5 – CPIO - Examples
• Create a fully qualified list of filenames under /boot: # find /boot > list ← • Make an archive of /boot called boot.backup using default bin format: # cpio -o -F boot.backup -v < list ← • Make an archive of /boot called boot.backup using new tar format # cpio -o -F boot.backup -H ustar -v < list ←

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111.5 – CPIO - Examples
• Create a fully qualified list of filenames under /boot: # find /boot > list ← • Make an archive of /boot called boot.backup using default bin format: # cpio -o -F boot.backup -v < list ← • Make an archive of /boot called boot.backup using new tar format # cpio -o -F boot.backup -H ustar -v < list ← • Use tar to list the contents of the boot.backup tar archive # tar -tvf boot.backup ←

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111.5 – CPIO - Examples

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111.5 – CPIO - Examples
• List the contents of the boot.backup archive # cpio -i -F boot.backup --list ←

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111.5 – CPIO - Examples
• List the contents of the boot.backup archive # cpio -i -F boot.backup --list ← • Restore all files in boot.backup to original locations # cpio -i -F boot.backup ←

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111.5 – CPIO - Examples
• List the contents of the boot.backup archive # cpio -i -F boot.backup --list ← • Restore all files in boot.backup to original locations # cpio -i -F boot.backup ← • Restore all files in under /boot/grub in boot.backup to original locations # cpio -i -F boot.backup /boot/grub/* ←

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111.5 – CPIO - Examples
• List the contents of the boot.backup archive # cpio -i -F boot.backup --list ← • Restore all files in boot.backup to original locations # cpio -i -F boot.backup ← • Restore all files in under /boot/grub in boot.backup to original locations # cpio -i -F boot.backup /boot/grub/* ← • Make a replica of /boot under /root/boot # cpio -p /root <list ←

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111.6 – Maintain system time [3]
111.6 – Objective
Candidate should be able to properly maintain the system time and synchronize the clock over NTP. Tasks include setting the system date and time, setting the BIOS clock to the correct time in UTC, configuring the correct timezone for the system and configuring the system to correct clock drift to match NTP clock.

111.6 – Key files, terms, and utilities include:
date hwclock ntpd ntpdate /usr/share/zoneinfo /etc/timezone /etc/localtime /etc/ntp.conf /etc/ntp.drift

111.6 – Resources
TBA

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111.6 – Date: Display or Set System Date & Time
The date command without any options will print the current date and time. The date will be relative to any timezone set for the machine. [andy@Node4]$ date ← Tue May 21 09:57:51 EST 2002

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111.6 – Date: Options to the Date command
-I Output an ISO-8601 compliant date (YYYY-MM-DD) $ date -I ← 2002-05-21 -R Output an RFC-822 compliant date (Local time + GMT 0ffset) $ date -R ← Tue, 21 May 2002 10:14:09 +1000 -r <file> Display the last modification time of file $ date -r ˜/ivr/va/src/va.c ← Mon May 20 12:55:48 EST 2002

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111.6 – Date: Options to the Date command
-d <STRING> Display date described by string instead of now $ date -d "last Monday 4 years ago" ← Mon May 18 00:00:00 EST 1998 -u Display UTC time & date instead of localtime $ date ← Tue May 21 10:55:34 EST 2002 $ date -u ← Tue May 21 00:55:34 UTC 2002

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111.6 – Date: Options to the Date command
-s <date> Set the system time (must be superuser) # date -s "Tue May 21 10:03:06 EST 2002" ← Tue May 21 10:03:06 EST 2002 +FORMAT Display date in user defined format $ date +"Today is %A, %d %B, %Y" ← Today is Tuesday, 21 May, 2002

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111.6 – hwclock: RTC <==>System clock
Hwclock is used to do the following: • Set the system clock from the Hardware clock • Set the hardware clock from the system clock • Show the time/date held by the RTC • Adjust the RTC to account for clock drift The Real Time Clock (RTC) is the hardware clock and is located on the motherboard of the system. This is what keeps track of the time when the system is not powered up. The system clock is maintained in the Linux kernel and is used while the system is running.

203

111.6 – hwclock: Set System clock to Hardware clock
• To set the system time from the RTC, use the following option to hwclock: hwclock -s (or hwclock --hctosys)

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111.6 – hwclock: Set System clock to Hardware clock
• To set the system time from the RTC, use the following option to hwclock: hwclock -s (or hwclock --hctosys)

• To set the RTC from the system time, use this option: hwclock -w (or hwclock --systohc)

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111.6 – hwclock: Set System clock to Hardware clock
• To set the system time from the RTC, use the following option to hwclock: hwclock -s (or hwclock --hctosys)

• To set the RTC from the system time, use this option: hwclock -w (or hwclock --systohc)

• To display the contents of the RTC, use this option: hwclock -r (or hwclock --show)

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111.6 – hwclock: Set System clock to Hardware clock
• To set the system time from the RTC, use the following option to hwclock: hwclock -s (or hwclock --hctosys)

• To set the RTC from the system time, use this option: hwclock -w (or hwclock --systohc)

• To display the contents of the RTC, use this option: hwclock -r (or hwclock --show)

• To adjsut the RTC for clock drift, use this option: hwclock -a (or hwclock --adjust)

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111.6 – hwclock: Set System clock to Hardware clock
• To set the system time from the RTC, use the following option to hwclock: hwclock -s (or hwclock --hctosys)

• To set the RTC from the system time, use this option: hwclock -w (or hwclock --systohc)

• To display the contents of the RTC, use this option: hwclock -r (or hwclock --show)

• To adjsut the RTC for clock drift, use this option: hwclock -a (or hwclock --adjust) Note that the file /etc/adjtime is used to hold information about the extent to which (and direction) your RTC drifts

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111.6 – NTP - Network Time Protocol
NTP is a time protocol used to synchronise a systems clock to master time source. For example, the CSIRO maintains a nationwide time source with atomic clock accuracy. As a user I can synchronise my system to that time source by sending a request to the CSIRO’s ntp server.

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111.6 – NTP - Network Time Protocol
NTP is a time protocol used to synchronise a systems clock to master time source. For example, the CSIRO maintains a nationwide time source with atomic clock accuracy. As a user I can synchronise my system to that time source by sending a request to the CSIRO’s ntp server. Features and properties of NTP include: • NTP takes into account the time taken to send/receive NTP packets • Uses the UDP protocol • Uses Port 123 plus one other unpriveledged port (1024:65535) • Can operate in both client & server modes • There are 3 versions of the protocol (ntp1, ntp2 & ntp3) • Available for Unix & Windows machines.

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