source: postlfs/config/profile.xml@ b4b71892

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<sect1 id="postlfs-config-profile" xreflabel="The Bash Shell Startup Files">
<?dbhtml filename="profile.html"?>
<title>The Bash Shell Startup Files</title>

<para>The shell program <filename>/bin/bash</filename> (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 <filename class="directory">/etc</filename> directory generally provide global
settings. If an equivalent file exists in your home directory it may
override the global settings.
</para>

<para>An interactive login shell is started after a successful login, using
<filename>/bin/login</filename>, by reading the <filename>/etc/passwd</filename> 
file.  This shell invocation normally reads <filename>/etc/profile</filename> 
and its private equivalent <filename>~/.bash_profile</filename> upon startup.</para>

<para>An interactive non-login shell is normally started at the command-line
(e.g.,  <prompt>[prompt]$</prompt><command>/bin/bash</command>) or by the
<command>/bin/su</command> command.  An interactive non-login shell is also
started with a terminal program such as <command>xterm</command> or
<command>konsole</command> from within a graphical environment. This type of
shell invocation normally copies the parent environment and then reads the
user's <filename>~/.bashrc</filename> file for additional startup configuration
instructions.</para>

<para>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.</para>

<para> The file <filename>~/.bash_logout</filename> is not used for an
invocation of the shell.  It is read and executed when a user exits from an
interactive login shell.</para>

<para>To the standard files, we also add <filename>/etc/bashrc</filename>
which is called from the user's <filename>~/.bashrc</filename> for 
system wide initialization of non-login shells.</para>

<para>For more information see <command>info bash</command> -- 
<emphasis role="strong">Nodes: Bash Startup Files and Interactive
Shells.</emphasis></para>

<sect2>
<title><filename>/etc/profile</filename></title>

<para>Here is a base <filename>/etc/profile</filename>. This file starts by
setting up some helper functions and some basic parameters.  It specifies some
<filename>bash</filename> 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
<filename class='directory'>/etc/profile.d</filename> directory to provide most
initialization.  </para>

<para>For more information on the escape sequences you can use for your prompt
(e.g.,  the <envar>PS1</envar> environment variable) see <command>info
bash</command> -- <emphasis role="strong">Node: Printing a
Prompt.</emphasis></para>

<screen><userinput><command>cat &gt; /etc/profile &lt;&lt; "EOF"</command>
# Begin /etc/profile
# Written for Beyond Linux From Scratch
# by James Robertson &lt;jameswrobertson@earthlink.net&gt;
# modifications by Dagmar d'Surreal &lt;rivyqntzne@pbzpnfg.arg&gt;
 
# 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="&amp;:[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
<command>EOF</command></userinput></screen>

<para>Now create the <filename class='directory'>/etc/profile.d</filename> directory.</para>

<screen><userinput><command>install --directory --mode=0755 --owner=root --group=root /etc/profile.d</command></userinput></screen>

<sect3>
<title><filename>/etc/profile.d/dircolors.sh</filename></title>

<para>This script uses the <filename>~/.dircolors</filename> and
<filename>/etc/dircolors</filename> files to control the colors of file names in a
directory listing. They control colorized output of things like <command>ls
--color</command>.  The explaination of how to initialize these files is at the
end of this section.  </para>


<screen><userinput><command>cat &gt; /etc/profile.d/dircolors.sh &lt;&lt; "EOF"</command>
# 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'
<command>EOF</command></userinput></screen>
</sect3>


<sect3>
<title><filename>/etc/profile.d/extrapaths.sh</filename></title>

<para>This script adds several useful paths to the <envar>PATH</envar> and
<envar>PKG_CONFIG_PATH</envar> 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.</para>
 
<screen><userinput><command>cat &gt; /etc/profile.d/extrapaths.sh &lt;&lt; "EOF"</command>
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
<command>EOF</command></userinput></screen>
</sect3>

<sect3>
<title><filename>/etc/profile.d/readline.sh</filename></title>

<para>This script sets up the default <filename>inputrc</filename> configuration file.
If the user does not have individual settings, it uses the global file.</para>

<screen><userinput><command>cat &gt; /etc/profile.d/readline.sh &lt;&lt; "EOF"</command>
# Setup the INPUTRC environment variable.
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ] ; then
        INPUTRC=/etc/inputrc
fi
export INPUTRC
<command>EOF</command></userinput></screen>
</sect3>

<sect3>
<title><filename>/etc/profile.d/tinker-term.sh</filename></title>

<para>Some applications need a specific <envar>TERM</envar> setting to support color.</para>

<screen><userinput><command>cat &gt; /etc/profile.d/tinker-term.sh &lt;&lt; "EOF"</command>
# 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
<command>EOF</command></userinput></screen>
</sect3>

<sect3>
<title><filename>/etc/profile.d/umask.sh</filename></title>
 
<para>Setting the <command>umask</command> 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.</para>

<screen><userinput><command>cat &gt; /etc/profile.d/umask.sh &lt;&lt; "EOF"</command>
# 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
<command>EOF</command></userinput></screen>
</sect3>

<sect3>
<title><filename>/etc/profile.d/X.sh</filename></title>

<para>If <application>X</application> is installed, we also update the <envar>PATH</envar>
and <envar>PKG_CONFIG_PATH</envar> variables.</para>

<screen><userinput><command>cat &gt; /etc/profile.d/X.sh &lt;&lt; "EOF"</command>
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
<command>EOF</command></userinput></screen>
</sect3>

<sect3>
<title><filename>/etc/profile.d/xterm-titlebars.sh</filename></title>
 
<para>This script shows an example of a different way of setting the prompt.  The normal
variable, <envar>PS1</envar>, is supplemented by <envar>PROMPT_COMMAND</envar>.
If set, the value of <envar>PROMPT_COMMAND</envar> is executed as a command prior to 
issuing each primary prompt. </para>
 
<screen><userinput><command>cat &gt; /etc/profile.d/xterm-titlebars.sh &lt;&lt; "EOF"</command>
# 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
<command>EOF</command></userinput></screen>

<para>Other initialization can easily be added to the <filename>profile</filename>
by adding additional scripts to the 
<filename class='directory'>/etc/profile.d</filename> directory.</para>
</sect3>
</sect2>

<sect2>
<title><filename>/etc/bashrc</filename></title>
<para>Here is a base <filename>/etc/bashrc</filename>.  Comments in the
file should explain everything you need.</para>

<screen><userinput><command>cat &gt; /etc/bashrc &lt;&lt; "EOF"</command>
# Begin /etc/bashrc 
# Written for Beyond Linux From Scratch 
# by James Robertson &lt;jameswrobertson@earthlink.net&gt;

# 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 <application>X</application> 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
<command>EOF</command></userinput></screen>
</sect2>


<sect2>
<title><filename>~/.bash_profile</filename></title>

<para>Here is a base <filename>~/.bash_profile</filename>.  If you want each
new user to have this file automatically, just change the output of
the command to <filename>/etc/skel/.bash_profile</filename> and check the
permissions after the command is run. You can then copy
<filename>/etc/skel/.bash_profile</filename> to the home directories of already
existing users, including root, and set the owner and group appropriately.
</para>

<screen><userinput><command>cat &gt; ~/.bash_profile &lt;&lt; "EOF"</command>
# Begin ~/.bash_profile
# Written for Beyond Linux From Scratch
# by James Robertson &lt;jameswrobertson@earthlink.net&gt;
# updated by Bruce Dubbs &lt;bdubbs@linuxfromscratch.org&gt;

# 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
<command>EOF</command></userinput></screen>
</sect2>
 
<sect2>
<title><filename>~/.bashrc</filename></title>

<para>Here is a base <filename>~/.bashrc</filename>.  The comments and
instructions for using <filename class="directory">/etc/skel</filename> for
<filename>.bash_profile</filename> above also apply here. Only the target file
names are different.</para>

<screen><userinput><command>cat &gt; ~/.bashrc &lt;&lt; "EOF"</command>
# Begin ~/.bashrc
# Written for Beyond Linux From Scratch
# by James Robertson &lt;jameswrobertson@earthlink.net&gt;

# 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
<command>EOF</command></userinput></screen>
</sect2>
 
 
<sect2>
<title><filename>~/.bash_logout</filename></title>

<para>This is an empty <filename>~/.bash_logout</filename> that can be used as
a template.  You will notice that the base <filename>~/.bash_logout</filename>
does not include a <userinput>clear</userinput> command.  This is because the
clear is handled in the <filename>/etc/issue</filename> file.</para>

<screen><userinput><command>cat &gt; ~/.bash_logout &lt;&lt; "EOF"</command>
# Begin ~/.bash_logout
# Written for Beyond Linux From Scratch
# by James Robertson &lt;jameswrobertson@earthlink.net&gt;

# Personal items to perform on logout.

# End ~/.bash_logout
<command>EOF</command></userinput></screen>
</sect2>
 
 
<sect2>
<title><filename>/etc/dircolors</filename></title>

<para> If you want to use the <filename>dircolors</filename> capability, then
run the following command. The <filename class="directory">/etc/skel</filename>
setup steps seen above also can be used here to provide a
<filename>.dircolors</filename> 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.
</para>

<screen><userinput><command>dircolors -p > /etc/dircolors</command></userinput></screen>

<para>If you wish to customize the colors used for different file types, you can
edit the <filename>/etc/dircolors</filename> file.  The instructions for setting 
the colors are embedded in the file.</para>


<para>Finally, Ian Macdonald has written an excellent collection of tips and
tricks to enhance your shell environment.  You can read it online at
<ulink
url="http://www.caliban.org/bash/index.shtml">http://www.caliban.org/bash/index.shtml</ulink>.</para>
</sect2>
</sect1>