Mini Shell

#!/usr/bin/sh
# Copyright 1994 David C. Niemi.
# Copyright 1997,2001,2002 Alain Knaff.
# This file is part of mtools.
#
# Mtools is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Mtools is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Mtools.  If not, see <http://www.gnu.org/licenses/>.
#
# tgz [destination [source...] ]
#
# Make a gzip'd tar archive $1 (or stdout) out of specified files
# (or, if not specified, from everything in the current directory)
#
# Requires gzip in the user's path.
#
# Requires gnu tar (or something close) in the user's path
# due to use of --exclude, --totals and -S.
#
# 1994/02/19	DCN	Created
# 1994/12/01	DCN	Cleanup and major improvements
#
# Copyright (C) 1994 David C. Niemi (niemi@tuxers.net)
# The author requires that any copies or derived works include this
# copyright notice; no other restrictions are placed on its use.
#

set -e
set -u

Error ()
{	echo "Error: $0: ${@-}." >&2
	exit 1
}

if [ $# = 0 ]; then
	dest=
	src=.
	tar cvf - . | gzip -9v
	exit 0
elif [ $# = 1 ]; then
	dest=$1
	src=.
else
	dest=$1
	shift
	src="${@-}"
fi

case $dest in
"" | . | .. | */ | */. | */.. )
	echo "Usage: $0: [destination [source...] ]" >&2
	exit 1
	;;
*.t?z | *.?z | *.z | *.Z | *.tz | *.tz? )
	;;
*)
	dest=${dest}.tgz	## Add on .tgz as default suffix
esac

if [ -h "$dest" ]; then
	Error "Destination file \"$dest\" already exists as a symbolic link"
elif [ -f "$dest" ]; then
	Error "Destination \"$dest\" already exists as a file"
elif [ -d "$dest" ]; then
	Error "Destination \"$dest\" already exists as a directory"
fi
if [ -z "$dest" -o "X$dest" = 'X-' ]; then
	echo "Writing gzipp'd tar archive to standard output." >&2
	tar cvfS - -- $src | gzip -9v
else
	echo "Writing gzip'd tar archive to \"$dest\"." >&2
	tar -cvS --totals --exclude "$dest" -f - -- $src | gzip -9v > "$dest" 
	ls -l "$dest" >&2
fi

exit 0