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 using a shell program (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 invocations, only the environment inherited from 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.
Many distributions use /etc/bashrc
for
system wide initialization of non-login shells. This file is usually
called from the user's ~/.bashrc
file
and is not built directly into bash itself. This convention is
followed in this section.
For more information see info bash -- Nodes: Bash Startup Files and Interactive Shells.
Most of the instructions below are used to create files located in
the /etc
directory structure which
requires you to execute the commands as the root
user. If you elect to create the files in
user's home directories instead, you should run the commands as an
unprivileged user.
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 of the initialization.
For more information on the escape sequences you can use for your
prompt (i.e., 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"
}
export -f pathremove pathprepend pathappend
# Set the initial path
export PATH=/bin:/usr/bin
if [ $EUID -eq 0 ] ; then
pathappend /sbin:/usr/sbin
unset HISTFILE
fi
# Setup some environment variables.
export HISTSIZE=1000
export HISTIGNORE="&:[bf]g:exit"
# Set some defaults for graphical systems
export XDG_DATA_DIRS=/usr/share
# Setup a red prompt for root and a green one for users.
NORMAL="\[\e[0m\]"
RED="\[\e[1;31m\]"
GREEN="\[\e[1;32m\]"
if [[ $EUID == 0 ]] ; then
PS1="$RED\u [ $NORMAL\w$RED ]# $NORMAL"
else
PS1="$GREEN\u [ $NORMAL\w$GREEN ]\$ $NORMAL"
fi
for script in /etc/profile.d/*.sh ; do
if [ -r $script ] ; then
. $script
fi
done
# End /etc/profile
EOF
Now create the /etc/profile.d
directory, where the individual initialization scripts are
placed:
install --directory --mode=0755 --owner=root --group=root /etc/profile.d
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 explanation of how to initialize
these files is at the end of this section.
cat > /etc/profile.d/dircolors.sh << "EOF"
# Setup for /bin/ls and /bin/grep 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'
alias grep='grep --color=auto'
EOF
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 specifying 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
if [ -d ~/bin ]; then
pathprepend ~/bin
fi
#if [ $EUID -gt 99 ]; then
# pathappend .
#fi
EOF
This script sets up the default inputrc
configuration file. If the user does
not have individual settings, it uses the global file.
cat > /etc/profile.d/readline.sh << "EOF"
# Setup the INPUTRC environment variable.
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ] ; then
INPUTRC=/etc/inputrc
fi
export INPUTRC
EOF
Setting the umask value is important for security. Here the default group write permissions are turned off for system users and when the user name and group name are not the same.
cat > /etc/profile.d/umask.sh << "EOF"
# By default, the umask should be set.
if [ "$(id -gn)" = "$(id -un)" -a $EUID -gt 99 ] ; then
umask 002
else
umask 022
fi
EOF
This script sets an environment variable necessary for native language support. A full discussion on determining this variable can be found on the LFS Bash Shell Startup Files page.
cat > /etc/profile.d/i18n.sh << "EOF"
# Set up i18n variables
export LANG=<ll>
_<CC>
.<charmap>
<@modifiers>
EOF
Other initialization can easily be added to the profile
by adding additional scripts to the
/etc/profile.d
directory.
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>
# updated by Bruce Dubbs <bdubbs@linuxfromscratch.org>
# 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 colored /bin/ls and /bin/grep commands. Used in conjunction
# with code in /etc/profile.
alias ls='ls --color=auto'
alias grep='grep --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.]
NORMAL="\[\e[0m\]"
RED="\[\e[1;31m\]"
GREEN="\[\e[1;32m\]"
if [[ $EUID == 0 ]] ; then
PS1="$RED\u [ $NORMAL\w$RED ]# $NORMAL"
else
PS1="$GREEN\u [ $NORMAL\w$GREEN ]\$ $NORMAL"
fi
# End /etc/bashrc
EOF
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
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
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
If you want to use the dircolors
capability, then run the following command. The /etc/skel
setup steps shown 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.
Last updated on 2014-02-27 20:59:01 -0800