2 Shells, Scripting, Programming & Compiling

1.109.1 Customize and use the shell environment Weight 5
Linux Professional Institute Certification — 102

2.109.1 Customise and use the shell environment [] 2.109.2 Customise or Write Simple Scrips [] Customise and Use the Shell Environment 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. Customise and Use the Shell Environment ~/.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) 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 Bash Aliases 1

Geoffrey Robertson ge@ffrey.com Nick Urbanik nicku@nicku.org 2005 July
Description of Objective

Candidate should be able to customize 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.
Key files, terms, and utilities include:

~/.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)

3 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 Bash Functions • 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 Bash Functions 1$ function look() { pwd; ls;} 2 $ function look { pwd; ls; } 3 $ look() { pwd; ls;} 4 •$ > > > > look() { pwd; ls; } Bash Functions 1A function that uses a command line argument: •$ > > > 2 • 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

4

laps () {← ls -l $1 ps aux | grep ‘/usr/bin/basename $1‘ }

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Bash Functions 1$ function look() pwd; ls; 2 $ look() { pwd; ls } 3 $ function look() {pwd; ls;}