Customizing bash with configuration files

Most commands you type on the command line can be placed in a special file, to be evaluated when you log in or start a new bash session. It's common to customize your shell by putting function definitions, aliases, and environment variable settings in one of these files.

Common commands to put into a configuration file include the following:

# Define my colors for ls 
LS_COLORS='no=00:di=01;46:ln=00;36:pi=40;33:so=00;35:bd=40;33;01' 
export LS_COLORS 
# My primary prompt 
PS1='Hello $USER'; export PS1 
# Applications I install outside the normal distro paths 
PATH=$PATH:/opt/MySpecialApplication/bin; export PATH 
# Shorthand for commands I use frequently 
function lc () {/bin/ls -C $* ; }

What customization file should I use?

Linux and Unix have several files that might hold customization scripts. These configuration files are divided into three camps—those sourced on login, those evaluated when an interactive shell is invoked, and files evaluated whenever a shell is invoked to process a script file.