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. 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. This shell invocation normally reads /etc/profile
and its private equivalent ~/.bash_profile upon startup.
An interactive non-login shell is normally started at the command-line
(e.g. [prompt]$/bin/bash) or by the
/bin/su command. An interactive non-login shell is also
started with a terminal program such as xterm or
konsole from within a graphical environment. This type of
shell invocation normally copies the parent environment and then reads the
user's ~/.bashrc file for additional startup configuration
instructions.
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 these shell invocatinos, only
the environment inherited form the parent shell is used.
The file ~/.bash_logout is not used for an
invocation of the shell. It is read and executed when a user exits from an
interactive login shell.
To the standard files, we also add /etc/bashrc
which is called from the user's ~/.bashrc for
system wide initialization of non-login shells.
For more information see info bash --
Nodes: Bash Startup Files and Interactive
Shells.
/etc/profile
Here is a base /etc/profile. This file starts by
setting up some helper functions and some basic parameters. It specifies some
bash history parameters and, for security purposes,
disables keeping a permanent history file for the root user. It also sets a
default user prompt. It then calls small, single purpose scripts in the
/etc/profile.d directory to provide most
initialization.
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>
# modifications by Dagmar d'Surreal <rivyqntzne@pbzpnfg.arg>
# 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.
# Functions to help us manage paths. Second argument is the name of the
# path variable to be modified (default: PATH)
pathremove () {
local IFS=':'
local NEWPATH
local DIR
local PATHVARIABLE=${2:-PATH}
for DIR in ${!PATHVARIABLE} ; do
if [ "$DIR" != "$1" ] ; then
NEWPATH=${NEWPATH:+$NEWPATH:}$DIR
fi
done
export $PATHVARIABLE="$NEWPATH"
}
pathprepend () {
pathremove $1 $2
local PATHVARIABLE=${2:-PATH}
export $PATHVARIABLE="$1${!PATHVARIABLE:+:${!PATHVARIABLE}}"
}
pathappend () {
pathremove $1 $2
local PATHVARIABLE=${2:-PATH}
export $PATHVARIABLE="${!PATHVARIABLE:+${!PATHVARIABLE}:}$1"
}
if [ $EUID -eq 0 ] ; then
unset HISTFILE
fi
# Setup some environment variables.
export HISTSIZE=1000
export HISTIGNORE="&:[bf]g:exit"
#export PS1="[\u@\h \w]\\$ "
export PS1='\u@\h:\w\$ '
for script in /etc/profile.d/*.sh ; do
if [ -x $script ] ; then
. $script
fi
done
# Now to clean up after ourselves
unset pathremove pathprepend pathappend
# End /etc/profile
EOF
Now create the /etc/profile.d directory.
install --directory --mode=0755 --owner=root --group=root /etc/profile.d
/etc/profile.d/dircolors.sh
This script uses the ~/.dircolors and
/etc/dircolors files to control the colors of file names in a
directory listing. They control colorized output of things like ls
--color. The explaination of how to initialize these files is at the
end of this section.
cat > /etc/profile.d/dircolors.sh << "EOF"
# 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
alias ls='ls --color=auto'
EOF
/etc/profile.d/extrapaths.sh
This script adds several useful paths to the PATH and
PKG_CONFIG_PATH environment variables. If you want, you can uncomment
the last section to put a dot at the end of your path. This will allow executables in the
current working directory to be executed without specifiying a ./, however
you are warned that this is generally considered a security hazard.
cat > /etc/profile.d/extrapaths.sh << "EOF"
if [ -d /usr/local/lib/pkgconfig ] ; then
pathappend /usr/local/lib/pkgconfig PKG_CONFIG_PATH
fi
if [ -d /usr/local/bin ]; then
pathprepend /usr/local/bin
fi
if [ -d /usr/local/sbin -a $EUID -eq 0 ]; then
pathprepend /usr/local/sbin
fi
for directory in $(find /opt/*/lib/pkgconfig -type d); do
pathappend $directory PKG_CONFIG_PATH
done
for directory in $(find /opt/*/bin -type d); do
pathappend $directory
done
if [ -d ~/bin ]; then
pathprepend ~/bin
fi
#if [ $EUID -gt 99 ]; then
# pathappend .
#fi
EOF
/etc/profile.d/readline.sh
This script sets up the default inputrc configuration file.
If the user does not have individual settings, it uses the global file.
cat > /etc/profile.d/readline.sh << "EOF"
# Setup the INPUTRC environment variable.
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ] ; then
INPUTRC=/etc/inputrc
fi
export INPUTRC
EOF
/etc/profile.d/tinker-term.sh
Some applications need a specific TERM setting to support color.
cat > /etc/profile.d/tinker-term.sh << "EOF"
# This will tinker with the value of TERM in order to convince certain apps
# that we can, indeed, display color in their window.
if [ -n "$COLORTERM" ]; then
export TERM=xterm-color
fi
if [ "$TERM" = "xterm" ]; then
export TERM=xterm-color
fi
EOF
/etc/profile.d/umask.sh
Setting the umask value is important for security. Here
we turn off the default group write permissions for system users and when the
user name and group name are not the same.
cat > /etc/profile.d/umask.sh << "EOF"
# By default we want the umask to get set.
if [ "$(id -gn)" = "$(id -un)" -a $EUID -gt 99 ] ; then
umask 002
else
umask 022
fi
EOF
/etc/profile.d/X.sh
If X is installed, we also update the PATH
and PKG_CONFIG_PATH variables.
cat > /etc/profile.d/X.sh << "EOF"
if [ -x /usr/X11R6/bin/X ]; then
pathappend /usr/X11R6/bin
fi
if [ -d /usr/X11R6/lib/pkgconfig ] ; then
pathappend /usr/X11R6/lib/pkgconfig PKG_CONFIG_PATH
fi
EOF
/etc/profile.d/xterm-titlebars.sh
This script shows an example of a different way of setting the prompt. The normal
variable, PS1, is supplemented by PROMPT_COMMAND.
If set, the value of PROMPT_COMMAND is executed as a command prior to
issuing each primary prompt.
cat > /etc/profile.d/xterm-titlebars.sh << "EOF"
# The substring match ensures this will work for "xterm" and "xterm-xfree86".
if [ "${TERM:0:5}" = "xterm" ]; then
PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME} : ${PWD}\007"'
export PROMPT_COMMAND
fi
EOF
Other initialization can easily be added to the profile
by adding additional scripts to the
/etc/profile.d directory.
/etc/bashrc
Here is a base /etc/bashrc. Comments in the
file should explain everything you need.
cat > /etc/bashrc << "EOF"
# Begin /etc/bashrc
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# System wide aliases and functions.
# System wide environment variables and startup programs should go into
# /etc/profile. Personal environment variables and startup programs
# should go into ~/.bash_profile. Personal aliases and functions should
# go into ~/.bashrc
# Provides a colored /bin/ls command. Used in conjunction with code in
# /etc/profile.
alias ls='ls --color=auto'
# Provides prompt for non-login shells, specifically shells started
# in the X environment. [Review the LFS archive thread titled
# PS1 Environment Variable for a great case study behind this script addendum.]
#export PS1="[\u@\h \w]\\$ "
export PS1='\u@\h:\w\$ '
# End /etc/bashrc
EOF
~/.bash_profile
Here is a base ~/.bash_profile. If you want each
new user to have this file automatically, just change the output of
the 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>
# updated by Bruce Dubbs <bdubbs@linuxfromscratch.org>
# 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.
append () {
# First remove the directory
local IFS=':'
local NEWPATH
for DIR in $PATH; do
if [ "$DIR" != "$1" ]; then
NEWPATH = ${NEWPATH:+$NEWPATH:}$DIR
fi
done
# Then append the directory
export PATH=$NEWPATH:$1
}
if [ -f "$HOME/.bashrc" ] ; then
source $HOME/.bashrc
fi
if [ -d "$HOME/bin" ] ; then
append $HOME/bin
fi
unset append
# End ~/.bash_profile
EOF
~/.bashrc
Here is a base ~/.bashrc. 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
~/.bash_logout
This is an empty ~/.bash_logout that can be used as
a template. 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
/etc/dircolors
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.
dircolors -p > /etc/dircolors
If you wish to customize the colors used for different file types, you can
edit the /etc/dircolors file. The instructions for setting
the colors are embedded in the file.
Finally, 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