– General Linux 2 – Customise and Use the Shell Environment []
(Linux Professional Institute Certification)
a .˜. /V\ // \\ @._.@ by: geoffrey robertson geoffrey@zip.com.au

$Id: gl2.109.1.slides.tex,v 1.2 2003/08/29 14:36:14 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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Shells, Scripting, Programming & Compiling
2.109.1 Customise and use the shell environment [] 2.109.2 Customise or Write Simple Scrips []

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Customise and Use the Shell Environment
Objective
Candidate should be able to customise shell environments to meet users’ needs. This objective includes setting environment variables (e.g. PATH) at login or when spawning a new shell. It also includes writing bash functions for frequently used sequences of commands.

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Customise and Use the Shell Environment
Key files, terms, and utilities
˜/.bash_profile ˜/.bash_login ˜/.profile ˜/.bashrc ˜/.bash_logout ˜/.inputrc function (Bash built-in command) export env set (Bash built-in command) unset (Bash built-in command)
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Bash Configuration Files
• When a user logs in to a bash shell the following configuration files are usually executed:

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Bash Configuration Files
• When a user logs in to a bash shell the following configuration files are usually executed: /etc/profile System wide profile, common to all users and shells

6-a

Bash Configuration Files
• When a user logs in to a bash shell the following configuration files are usually executed: /etc/profile System wide profile, common to all users and shells ˜/.bash profile Executed after /etc/profile at login

6-b

Bash Configuration Files
• When a user logs in to a bash shell the following configuration files are usually executed: /etc/profile System wide profile, common to all users and shells ˜/.bash profile Executed after /etc/profile at login ˜/.bashrc Executed after /.bash profile at login

6-c

Bash Configuration Files
• When a user logs in to a bash shell the following configuration files are usually executed: /etc/profile System wide profile, common to all users and shells ˜/.bash profile Executed after /etc/profile at login ˜/.bashrc Executed after /.bash profile at login • Note /.bashrc is executed when any new bash shell is spawned

6-d

Bash Aliases

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Bash Aliases
•

7-a

Bash Functions
• Functions work similarly to aliases but allow more complex constructions.

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Bash Functions
• Functions work similarly to aliases but allow more complex constructions. • They have the following syntax: $ [ function ] NAME() { COMMAND_LIST;} ←

8-a

Bash Functions
• Functions work similarly to aliases but allow more complex constructions. • They have the following syntax: $ [ function ] NAME() { COMMAND_LIST;} ← • Where function Optional tag NAME() The name of the function COMMAND LIST The body of the function

8-b

Bash Functions
• Functions work similarly to aliases but allow more complex constructions. • They have the following syntax: $ [ function ] NAME() { COMMAND_LIST;} ← • Where function Optional tag NAME() The name of the function COMMAND LIST The body of the function • Functions may be stored in ˜/.bashrc

8-c

Bash Functions
Function Example
• This simple function prints the current working directory and the list of files in it: $ function look() { pwd; ls;} ←

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Bash Functions
Function Example
• This simple function prints the current working directory and the list of files in it: $ function look() { pwd; ls;} ← • This function would be used like this: $ look ← /home/geoffrey/lpic/general-linux-2/notes CVS _whizzy_gl2.notes.fmt _whizzy_gl2.notes.pag

9-a

Bash Functions
Valid Function Definitions

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Bash Functions
Valid Function Definitions
• $ function look() { pwd; ls;}

10-a

Bash Functions
Valid Function Definitions
• $ function look() { pwd; ls;} • $ function look { pwd; ls; }

10-b

Bash Functions
Valid Function Definitions
• $ function look() { pwd; ls;} • $ function look { pwd; ls; } • $ look() { pwd; ls;}

10-c

Bash Functions
Valid Function Definitions
• $ function look() { pwd; ls;} • $ function look { pwd; ls; } • $ look() { pwd; ls;} •$ > > > > look() { pwd; ls; }

10-d

Bash Functions
Invalid Function Definitions

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Bash Functions
Invalid Function Definitions
• $ function look() pwd; ls;

11-a

Bash Functions
Invalid Function Definitions
• $ function look() pwd; ls;

• $ look() { pwd; ls }

11-b

Bash Functions
Invalid Function Definitions
• $ function look() pwd; ls;

• $ look() { pwd; ls } • $ function look() {pwd; ls;}

11-c

Bash Functions
Example from Jeffrey Dean’s Nutshell Book

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Bash Functions
Example from Jeffrey Dean’s Nutshell Book
• A function that uses a command line argument: $ > > > laps () { ← ls -l $1 ps aux | grep ‘/usr/bin/basename $1‘ }

12-a

Bash Functions
Example from Jeffrey Dean’s Nutshell Book
• A function that uses a command line argument: $ > > > laps () { ← ls -l $1 ps aux | grep ‘/usr/bin/basename $1‘ }

• Use the laps() function:
$ laps /usr/sbin/sshd ← -rwxr-xr-x 1 root root 276200 Jun 29 01:28 /usr/sbin/sshd root 255 0.0 0.3 2792 1216 ? S Aug31 0:00 /usr/sbin/sshd geoffrey 1187 0.0 0.1 1332 424 pts/1 R 14:39 0:00 grep sshd

12-b

The End

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