Setting bash as the default shell with grendel and hermite

D. Thiébaut

The end of this document shows how to create executable programs that can be run transparently of the operating system used.

1. Set bash as your default shell:

   		% chsh
   		Old shell: xxxxxxxxxxxxxxx
   		New shell: /local/bin/bash
   	

2. Create two .environment files: .environment.IRIX and .environment.SunOS

   Here are skeleton versions of both

   • .environment.SunOS

     	#!/bin/sh
     	export MANPATH=$HOME/man:/local/man:/local/man/pbm:/local/man/tcl:/usr/man
     	export CDPATH=.:$HOME:$HOME/public_html:$HOME/bin:
     	export EDITOR=/local/bin/emacs
     	export VISUAL=$EDITOR
     	export PAGER=/local/bin/less
     	TERM=vt100
     	export TERM TERMCAP
     	

   • .environment.IRIX

     	#!/bin/sh
     	export MANPATH=/usr/share/catman:/usr/share/man:/usr/catman:/usr/man:/usr/freeware/catman:$HOME/man
     	export CDPATH=.:$HOME:$HOME/public_html:$HOME/bin:$HOME/temp:$HOME/public_html/classes
     	export MSGVERB=text:action
     	export NOMSGLABEL=1
     	export NOMSGSEVERITY=1
     	export PAGER=/usr/local/bin/less
     	export TERM TERMCAP
     	export TERMMODE=0
     	

3. create a .bashrc file that will detect which OS it is running under, and will execute appropriate commands, and load either .environment.IRIX or .environment.SunOS.

   	# find out what OS we're running under
   	OS=`uname -s`
   
   	if [ `echo $OS | grep "IRIX"` ];  then
   	    OS="IRIX"
   	fi
   	export OS
   
   	# Load our environment (specific to the given OS)
   	if [ -f $HOME/.environment.$OS ]; then
   	    source $HOME/.environment.$OS
   	fi
   
   	#--- load SunOS stuff now ---------------------------------------------
   	if [ $OS = "SunOS" ]; then
   	
   		export OPENWINHOME=/usr/openwin
   		export MINICOM="-c on"
   
   		PATH="$PATH:/usr/X11/bin:/usr/andrew/bin:$OPENWINHOME/bin:/usr/games:."
   		LESS=-MM
   		eval tset
   
   		PS1='[\h]\n[\t] \w\$: '
   		PS2='> '
   		if [ ! "$SHELL" = "/bin/ash" ]; then # ash doesn't have aliases
   	 	 alias net='term < /dev/modem > /dev/modem 2> /dev/null&'
   		fi
   
   		alias dir=ls
   		alias h=history
   		alias a=alias
   		ignoreeof=10
   		export PATH DISPLAY LESS TERM PS1 PS2 ignoreeof
   		umask 066
   		biff y
   		HISTSIZE=32
   		MAILCHECK=60
   	fi
   
   	#--- load IRIX stuff now ---------------------------------------------
   	if [ "$OS" = "IRIX" ]; then
   
   		PATH="/usr/local/bin:/usr/freeware/bin:/sbin:/usr/bin:/usr/bin/X11:/usr/bsd:/usr/etc:/usr/sbin:/usr/java/bin:.:$HOME/bin"
   	
   		LESS=-MM
   		eval tset
   
   		PS1='[\h]\n[\t] \w\$: '
   		PS2='> '
   		if [ ! "$SHELL" = "/bin/ash" ]; then # ash doesn't have aliases
   		 alias net='term < /dev/modem > /dev/modem 2> /dev/null&'
   		fi
   
   		alias dir=ls
   		alias h=history
   		alias a=alias
   		ignoreeof=10
   		export PATH DISPLAY LESS TERM PS1 PS2 ignoreeof
   		umask 066
   		HISTSIZE=32
   		MAILCHECK=60
   
   	fi
   
   
   	#---- Stuff common to IRIX and SunOS ---------------------------------
   	# (put here commands that work under both Operating Systems.
   	

4. A related issue: if you want to run executables in your bin directory independently of the OS you use, follow the approach outlined below:

   Assume that you have a program called hello.c and want a working copy for both machines. Compile it on grendel and call the executable hello.SunOS, and the one for hermite hello.IRIX. Then create a shell file called hello that will test which OS it is running under and will select the appropriate executable. With bash it looks like this:

   	#! /local/bin/bash
   	OS=`uname -s`
           if [ `echo $OS | grep "IRIX"` ];  then
               OS="IRIX"
           fi
           hello.$OS $@
   	

   That works pretty well! Note: if you have exported the variable $OS in your .bashrc file, then $OS will be part of your environment, and you can skip Lines 2 to 5 of the shell file above:

   	#! /local/bin/bash
   	hello.$OS $@