tarize

#!/bin/sh

######################################################################
#
# TARIZE : Apply "tar.gz" to the Specified Directories
#
# This command converts a file or a directory into a "tar.gz" archive
# files. However, this requires some non-POSIX commands. That is one
# of the following patterns.
# (a) tar command
# (b) pax command that supports the "-z" option
# (c) pax command that does not support the "-z" option + gzip command
#
# === Usage ===
# Usage : tarize file_or_dir#1 [file_or_dir#2 [...]]
# Args  : file_or_dir ... the target file to be converted
#
#
# Written by Shell-Shoccar Japan (@shellshoccarjpn) on 2021-10-27
#
# This is a public-domain software (CC0). It means that all of the
# people can use this for any purposes with no restrictions at all.
# By the way, We are fed up with the side effects which are brought
# about by the major licenses.
#
######################################################################


######################################################################
# Initial configuration
######################################################################

# === Initialize shell environment ===================================
set -u
umask 0022
export LC_ALL=C
export PATH="$(command -p getconf PATH 2>/dev/null)${PATH+:}${PATH-}"
case $PATH in :*) PATH=${PATH#?};; esac
export UNIX_STD=2003  # to make HP-UX conform to POSIX

# === Usage printing function ========================================
print_usage_and_exit () {
  cat <<-USAGE 1>&2
	Usage : ${0##*/} file_or_dir#1 [file_or_dir#2 [...]]
	Args  : file_or_dir ... the target file to be converted
	Version : 2021-10-27 18:09:32 JST
	          (POSIX Bourne Shell/POSIX commands/archiver commands)
	USAGE
  exit 1
}
error_exit() {
  ${2+:} false && echo "${0##*/}: $2" 1>&2
  exit ${1:-0}
}

# === Make sure the dependent commands exist =========================
if   tar zcf - /dev/null >/dev/null 2>&1; then
  type=1
elif pax -wz /dev/null >/dev/null 2>&1; then
  type=2
elif pax -w  /dev/null >/dev/null 2>&1 && type gzip >/dev/null 2>&1; then
  type=3
else
  error_exit 1 'Dependent command(s) not found. See the header comment of me.'
fi


######################################################################
# Parse Arguments
######################################################################

case $# in 0) print_usage_and_exit;; esac


######################################################################
# Main
######################################################################

for Dir_target in "$@"; do
  case "$Dir_target" in
    /|..|../|.|./)  error_exit 1 "$Dir_target"': Invalid file or dir'
                    ;;
    /*)             Dir_base=${Dir_target%/*}
                    case "$Dir_base" in '') Dir_base='/';; esac
                    s=${Dir_target%/}
                    file_trg=${s##*/}
                    case "$file_trg" in '')
                      error_exit 1 "$Dir_target"': Invalid file or dir'
                    ;; esac
                    ;;
    ../*|./*)       Dir_base=$(cd "${Dir_target%/*}" && pwd)
                    case "$Dir_base" in '')
                      error_exit 1 "$Dir_target"': Invalid file or dir'
                    ;; esac
                    s=${Dir_target%/}
                    file_trg=${s##*/}
                    case "$file_trg" in '')
                      error_exit 1 "$Dir_target"': Invalid file or dir'
                    ;; esac
                    ;;
    *)              Dir_base=$(cd "./${Dir_target%/*}" && pwd)
                    case "$Dir_base" in '')
                      error_exit 1 "$Dir_target"': Invalid file or dir'
                    ;; esac
                    s=${Dir_target%/}
                    file_trg=${s##*/}
                    ;;
  esac
  case "$file_trg" in *.gz)
    echo "${0##*/}: $Dir_target: It is already gzipped, skip it." 1>&2
    continue
  ;; esac
  cd "$Dir_base" || error_exit 1 "$Dir_target"': Invalid file or dir'
  case $type in
    1) if ! tar zcpf ${file_trg}.tar.gz ${file_trg}; then
         echo "${0##*/}: $Dir_target: Failed to compress, skip it." 1>&2
         cd -; continue
       fi
       ;;
    2) if ! pax -wz ${file_trg} > ${file_trg}.tar.gz; then
         echo "${0##*/}: $Dir_target: Failed to compress, skip it." 1>&2
         cd -; continue
       fi
       ;;
    3) if   ! pax -w ${file_trg} > ${file_trg}.tar; then
         echo "${0##*/}: $Dir_target: Failed to compress, skip it." 1>&2
         continue
       elif ! gzip ${file_trg}.tar                ; then
         echo "${0##*/}: $Dir_target: Failed to compress, skip it." 1>&2
         cd -; continue
       fi
       ;;
  esac
  printf '%s.tar.gz\n' "$Dir_target" 1>&2
  rm -rf "${file_trg}"
  cd - >/dev/null 2>&1

done


######################################################################
# Finish
######################################################################

exit 0