gistfile1.txt

#!/bin/sh

comp=${COMPRESSOR:-$(which gzip 2>/dev/null)}
flags=""

case "${1}" in
	(compress) shift ;;
	(decompress) op="d"; flags="-d"; shift ;;
	(*) echo "Usage: ${0} (compress|decompress) [-vjJzZc] <...>" ; exit 1 ;;
esac

while getopts "vjJzZc" opt; do
	case "${opt}" in
		(v) flags="${flags} -v" ;;
		(j) comp=$(which bzip2 2>/dev/null) ;;
		(J) comp=$(which xz 2>/dev/null) ;;
		(z) comp=$(which gzip 2>/dev/null) ;;
		(c) comp="$(which compress 2>/dev/null) -f" ;;
		(Z) comp="$(which zstd 2>/dev/null) --no-progress --rm" ;;
		(*)
			echo "Usage: ${0} compress [-vjJzZc] <...>"
			printf "\t-v verbose\t-j use bzip2\n\t-J use xz"
			printf "\t-z use gzip (Def)\n\t-Z use zstdio\t-c use compress\n"
			exit 1 ;;
	esac
done

for archive in ${@}; do
	if test ! -z "${op}"; then
		mtype=$(file ${archive}|head -n1|awk '{print $2}')
		case "${mtype}" in
			(XZ) comp=$(which xz 2>/dev/null) ;;
			(Zstandard) comp="$(which zstd 2>/dev/null) --no-progress -f --rm" ;;
			(compress\'d) comp="$(which compress 2>/dev/null) -f" ;;
			(*) comp=$(which ${mtype} 2>/dev/null) ;;
		esac
	fi	
	test -e "${archive}" || continue && \
		${comp:-$(which gzip 2>/dev/null)} ${flags} ${archive} >/dev/null
done