Customizing the Bash Shell

Bash Shell Configuration

Bash shell configuration files


As we saw earlier we can create aliases and functions quite easily. However, to make these changes permanent we will probably want to permanently add this so that they are available at login. To configure Bash to use our custom settings we need to configure various configuration files that are used. Some of these files are only executed at "login", others are executed each time a new instance of your Bash shell is started. Some of Bash's configuration files are "System Wide", meaning they will apply to all users of Bash. Many are local and reside in your "/homedirectory/". These local configuration files will only apply to that particular user!




Bash Configuration Files and their Location



File Location Description
/etc/profile This is a "System wide" initialisation file that is executed during login. This file provides initial environment variables and initial "PATH" locations.
/etc/bashrc This again is a "System Wide" initialisation file. This file is executed each time a Bash shell is opened by a user. Here you can define your default prompt and add alias information. Values in this file can be overridden by their local ~/.bashrc entry.
~/.bash_profile If this file exists, it is executed automatically after /etc/profile during the login process. This file can be used by each user to add individual entries. The file however is only executed once at login and normally then runs the users .bashrc file.
~/.bash_login If the ".bash_profile" does not exist, then this file will be executed automatically at login.
~/.profile If the ".bash_profile" or ".bash_login" do not exist, then this file is executed automatically at login.
~/.bashrc This file contains individual specific configurations. This file is read at login and also each time a new Bash shell is started. Ideally, this is where you should place any aliases.
~/.bash_logout This file is executed automatically during logout
~/.inputrc This file is used to customize key bindings/key strokes.

Depending on the distribution you are using, you may not have all of the above mentioned local files. This is perfectly normal.

Example: .bash* files


john@john-desktop:~$ ls -al | grep ".bash"
-rw-------   1 john john    26000 Apr  4 20:51 .bash_history
-rw-r--r--   1 john john      220 Oct 22  2011 .bash_logout
-rw-r--r--   1 john john     3384 Oct 12 21:25 .bashrc

The above files were found in my home directory (example from an Ubuntu 14.04 LTS desktop).

bash_history


The file ".bash_history" is where the commands you have typed are stored. These can be displayed by simply issuing the "history" command or by issuing the "fc -l" command. If you wanted to repeat a command, you can simply specify the number of the command to be repeated. (Please make sure you request the correct command!)


root@john-desktop:~# fc -l
584	 cd ~john
585	 ls -rtl
586	 cat id.txt 
587	 usermod -G john,adm,dialout,fax,cdrom,floppy,tape,dip,video,plugdev,fuse,lpadmin,admin,sambashare,vboxusers john
588	 id john
589	 exit
590	 set -o vi
591	 clear
592	 du /tmp
593	 du -hs /tmp
594	 clear
595	 du -hs ~john
596	 exit
597	 set -o vi
598	 fc -l
599	 su - landoflinux
root@john-desktop:~# !599
su - landoflinux 
landoflinux@john-desktop:~$

Here we displayed our commands by issuing "fc -l", then I repeated a previously entered command which is identified by the number "599" by issuing !599. This then repeated my previous "su - landoflinux" command.