The Bash Shell Startup Files
The shell program /bin/bash (hereafter
referred to as just "the shell") uses a collection of startup files to
help create an environment to run in. Each file has a specific use and
may affect login and interactive environments differently. The files in
the /etc directory generally provide global
settings. If an equivalent file exists in your home directory it may
override the global settings.
An interactive login shell is started after a successful login, using
/bin/login, by reading the
/etc/passwd file. An
interactive non-login shell is started at the command-line (e.g.
[prompt]$/bin/bash). A non-interactive
shell is usually present when a shell script is running. It is non-interactive
because it is processing a script and not waiting for user input between
commands.
For more information see info bash --
Nodes: Bash Startup Files and Interactive
Shells.
The following files are used to make sure that the correct
environment is established for each of the ways the shell can be invoked:
/etc/profile and its private equivalent
~/.bash_profile, and
/etc/bashrc (unofficial) and its private equivalent
~/.bashrc.
The file ~/.bash_logout is not used for an
invocation of the shell. It is read by the shell when a user logs out
of the system.
The files /etc/profile and
~/.bash_profile are read when the shell is invoked
as an interactive login shell. The file ~/.bashrc
is read when the shell is invoked as an interactive non-login
shell and it reads /etc/bashrc if it exists
Also useful are the /etc/dircolors and
~/.dircolors files called from
/etc/profile. They control colorized output of
things like ls --color.
Here is a base /etc/profile. Comments in the
file should explain everything you need. For more information on the
escape sequences you can use for your prompt (e.g. the
PS1 environment variable) see info
bash -- Node: Printing a
Prompt.
cat > /etc/profile << "EOF"
# Begin /etc/profile
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# System wide environment variables and startup programs.
# System wide aliases and functions should go in /etc/bashrc. Personal
# environment variables and startup programs should go into
# ~/.bash_profile. Personal aliases and functions should go into
# ~/.bashrc.
# Function to help us manage paths
pathman () {
if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" ; then
if [ "$2" = "last" ] ; then
PATH=$PATH:$1
else
PATH=$1:$PATH
fi
fi
}
# Add to the standard path.
if [ $(id -u) = 0 ] ; then
if [ -d "/usr/local/sbin" ] ; then
pathman /usr/local/sbin last
fi
fi
if [ $(id -u) != 0 ] ; then
if [ -d "/usr/local/bin" ] ; then
pathman /usr/local/bin last
fi
fi
if [ -d "/usr/X11R6/bin" ] ; then
pathman /usr/X11R6/bin last
fi
# Setup some environment variables.
HISTSIZE=1000
HISTIGNORE="&:[bf]g:exit"
PS1="[\u@\h \w]\\$ "
# Setup the INPUTRC environment variable.
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ] ; then
INPUTRC=/etc/inputrc
fi
# Setup for /bin/ls to support color, the alias is in /etc/bashrc.
if [ -f "/etc/dircolors" ] ; then
eval $(dircolors -b /etc/dircolors)
if [ -f "$HOME/.dircolors" ] ; then
eval $(dircolors -b $HOME/.dircolors)
fi
fi
export PATH HISTSIZE HISTIGNORE PS1 LS_COLORS INPUTRC
# End /etc/profile
EOF
Here is a base /etc/bashrc. Comments in the
file should explain everything you need.
cat > /etc/bashrc << "EOF"
# Begin /etc/bashrc
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# System wide aliases and functions.
# System wide environment variables and startup programs should go into
# /etc/profile. Personal environment variables and startup programs
# should go into ~/.bash_profile. Personal aliases and functions should
# go into ~/.bashrc
# By default we want the umask to get set.
# Even for non-interactive and non-login shells.
if [ "$(id -gn)" = "$(id -un)" -a $(id -u) -gt 99 ] ; then
umask 002
else
umask 022
fi
# Provides a colored /bin/ls command. Used in conjunction with code in
# /etc/profile.
alias ls='ls --color=auto'
# Provides prompt for non-interactive shells, specifically shells started
# in the xfree environment. [Review archive thread titled PS1
# Environment Variable for a great case study behind this script
# addendum.]
export PS1="[\u@\h \w]\\$ "
# End /etc/bashrc
EOF
Here is a base ~/.bash_profile. Comments in
the file should explain everything you need. If you want each new user
to have this file automatically provided, just change the output of the
next command to /etc/skel/.bash_profile and check the
permissions after the command is run. You can then copy
/etc/skel/.bash_profile to the home directories of
already existing users, including root, and set the owner and group
appropriately.
cat > ~/.bash_profile << "EOF"
# Begin ~/.bash_profile
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# Personal environment variables and startup programs.
# Personal aliases and functions should go in ~/.bashrc. System wide
# environment variables and startup programs are in /etc/profile.
# System wide aliases and functions are in /etc/bashrc.
if [ -f "$HOME/.bashrc" ] ; then
source $HOME/.bashrc
fi
if [ -d "$HOME/bin" ] ; then
pathman $HOME/bin last
fi
export PATH
# End ~/.bash_profile
EOF
Here is a base ~/.bashrc. Comments in the
file should explain everything you need. The comments and
instructions for using /etc/skel for
.bash_profile above also apply here. Only the
target file names are different.
cat > ~/.bashrc << "EOF"
# Begin ~/.bashrc
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# Personal aliases and functions.
# Personal environment variables and startup programs should go in
# ~/.bash_profile. System wide environment variables and startup
# programs are in /etc/profile. System wide aliases and functions are
# in /etc/bashrc.
if [ -f "/etc/bashrc" ] ; then
source /etc/bashrc
fi
# End ~/.bashrc
EOF
Here is a base ~/.bash_logout. Comments in
the file should explain everything you need. You will notice that the
base ~/.bash_logout does not include a
clear command. This is because the clear is
handled in the /etc/issue file.
cat > ~/.bash_logout << "EOF"
# Begin ~/.bash_logout
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# Personal items to perform on logout.
# End ~/.bash_logout
EOF
If you want to use the dircolors capability
then run the following command. The /etc/skel setup
steps seen above also can be used here to provide a
.dircolors file when a new user is set up. As
before, just change the output file name on the following command and
assure the permissions, owner and group are correct on the files created
and/or copied.
/bin/dircolors -p > /etc/dircolors
Ian Macdonald has written an excellent collection of tips and
tricks to enhance your shell environment. You can read it online at
http://www.caliban.org/bash/index.shtml