popd

操作系统源代码

# Copyright (c) 1991 The Regents of the University of California.
# All rights reserved.
#
# This code is derived from software contributed to Berkeley by
# Kenneth Almquist.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. All advertising materials mentioning features or use of this software
#    must display the following acknowledgement:
#	This product includes software developed by the University of
#	California, Berkeley and its contributors.
# 4. Neither the name of the University nor the names of its contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
#	@(#)popd	5.1 (Berkeley) 3/7/91

# pushd, popd, and dirs --- written by Chris Bertin
# Pixel Computer Inc. ...!wjh12!pixel!pixutl!chris
# as modified by Patrick Elam of GTRI and Kenneth Almquist at UW

pushd () {
	SAVE=`pwd`
	if [ "$1" = "" ] 
	then	if [ "$DSTACK" = "" ]
		then	echo "pushd: directory stack empty."
			return 1
		fi
		set $DSTACK
		cd $1 || return
		shift 1
		DSTACK="$*"
	else	cd $1 > /dev/null || return
	fi
	DSTACK="$SAVE $DSTACK"
	dirs
}

popd () {
	if [ "$DSTACK" = "" ] 
	then	echo "popd: directory stack empty."
		return 1
	fi
	set $DSTACK
	cd $1
	shift
	DSTACK=$*
	dirs
}

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