Pushd, popd, dirs for stock SysV.3 Bourne shell

[David Barto]

In article <PCG.90Sep26164749 at odin.cs.aber.ac.uk> pcg at cs.aber.ac.uk (Piercarlo Grandi) writes:
>
>You will find appended a small shell script that defines under a stock
>System V Bourne shell the pushd, popd, dirs commands of csh(1). They are
>trivially adapted to the Korn shell. I have taken care to make them as
>robust as possible.
>

pushd, popd, and dirs --- written by Chris Bertin
Pixel Computer Inc. ...!wjh12!pixel!pixutl!chris
as modified by Patrick Elam of GTRI
modified by david barto to allow 'pushd +n'

cd is a function, which uses the 'builtin' keyword, available for
those who have the BRL mods to the shell.  (I think this can be changed
to 'eval'.)  It will look for PCDPATH and do chdirs down that path if
the directory can be found on it.

PCDPATH=". $HOME /burt/prj/common /burt/prj/sparc /archive2"
export PCDPATH
-----

cd () {
	PREVDIR="$CWD" 
	result=1
	if [ $# -lt 1 ] ; then
		builtin cd
		result=0
	elif [ -d $1 ] ; then
		builtin cd "$1" 
		result=0
	else
	    for i in $PCDPATH
	    do
		nxtdir=$i/$1
		# echo "try $nxtdir"
		if [ $result != 0 -a -d $nxtdir ] ; then
		    builtin cd "$nxtdir"
		    result=0
		fi
	    done
	    unset nxtdir
	fi
	if [ $result != 0 ] ; then
	    echo "$1: directory not found"
	else
	    CWD=`pwd` export CWD 
	    set +u 
	    if [ "$CWD" = "$HOME" ] 
	    then
		PFX="$HOST" 
		PS1=:~
	    else
		PS1=`echo "$CWD" | sed -e "s!^$HOME!~!"` PFX="$HOST": 
	    fi
	    umask 022
	    echo "$CWD" | egrep -s "/burt/prj/common|/x"
	    [ $? = 0 ] && umask 002
	    if [ "$TERM" = "wy75" ]
	    then
		wy75-title $PS1
		PS1="$PFX %e_ "
	    elif [ "$TWM_RUNNING" = 1 ]
	    then
		if [ "$TTY" != "" ]
		then
		    twm-title "$TTY:$PFX$PS1"
		else
		    twm-title "XX:$PFX$PS1"
		fi
		PS1="%e_ "
	    else
		PS1="$PFX$PS1 %t%n%e_ " 
	    fi
	    unset PFX 
	    set -u 
	fi
	return $result
}

# pushd, popd, and dirs --- written by Chris Bertin
# Pixel Computer Inc. ...!wjh12!pixel!pixutl!chris
# as modified by Patrick Elam of GTRI
# modified by david barto to allow 'pushd +n'

pushd () {
	SAVE=`pwd`
	_DSTACK="$SAVE $_DSTACK"
	if [ "$1" = "" ] 
	then
		if [ "$_DSTACK" = "$SAVE " ]
		then
			echo "pushd: directory stack empty."
			_DSTACK=""
			return 1
		fi
		set $_DSTACK
		cd $2
		set $_DSTACK
		shift 2
		_DSTACK="$SAVE $*"
	else
		case "$1" in
		+*)
			count=`echo $1 | sed 's/+//'`
			set $_DSTACK
			if [ $count -ge $# ] ; then
				echo "pushd: directory stack not that deep"
				shift
				_DSTACK=$*
				return 1
			fi
			TMP=
			while [ $count -gt 0 ]
			do
				TMP="$TMP $1"
				shift
				count=`expr $count - 1`
			done
			TD=$1
			shift
			_DSTACK="$TMP $*"
			unset TMP
			if [ -d $TD ]
			then
				cd $TD >&-
				unset TD
			else
				popd > /dev/null
				return 1
			fi
			;;
		*)
			cd $1
			if [ $? -eq 1 ] ; then
				popd > /dev/null
				return 1
			fi
			;;
		esac
	fi
	dirs
	return 0
}

popd () {
	if [ "$_DSTACK" = "" ]; then
		echo "popd: Directory stack empty"
		return 1
	fi
	case "$1" in
	+*)
		count=`echo $1 | sed 's/+//'`
		case "$count" in
		0)
			echo "popd: Must have positive count"
			return 1
			;;
		1)
			popd
			return 0
			;;
		*)
			_TMPSTK="`pwd` $_DSTACK"
			set $_TMPSTK
			if [ $count -gt $# ]; then
				echo "pushd: directory stack not that deep"
				return 1
			fi
			TMP=
			while [ $count -ge 1 ]
			do
				TMP="$TMP $1"
				shift
				count=`expr $count - 1`
			done
			shift		# trash dir requested
			_DSTACK="$* $TMP"
			set $_DSTACK
			shift		# trash 'pwd' from the top of the stack
			_DSTACK="$*"
			;;
		esac
		;;
	*)
		set $_DSTACK
		cd $1
		set $_DSTACK
		shift
		_DSTACK=$*
		;;
	esac
	dirs
	return 0
}

dirs () {
	echo "`pwd` $_DSTACK"
	return 0
}

xchng () {	# exchanged top two entries on the stack
	if [ "$_DSTACK" = "" ]
	then
		echo exchange directory stack empty
		return 1
	else
		pushd
		return 0
	fi
}
-- 
David Barto	uunet!megatek!barto	barto at network.ucsd.edu