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#!/bin/bash
#
# zopflipng-parallel
# Executes 'zopflipng' in parallel on all the files specified as arguments, overwriting the input files.
# Opionally, with option `-j<num>`, parallel execution can be limited to `<num>` processes at the same time.
#
#
# License: GNU GPL Version 3 or later (at your choice), see http://www.gnu.org/licenses/gpl-3.0.en.html (as of 2018-05-20).
#
#
# This program 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.
#
# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
#
# The version.
VERSION=0.1
# Abort on error
set -e
# How to output text to stdout:
stdout() {
# Don't use 'echo', since it might interpret leading '-e', '-E', '-n' and maybe others.
printf '%s\n' "$@"
}
# Write to stderr:
stderr() {
stdout "$@" 1>&2
}
# Print usage help:
printusage() {
stdout "$0: Optimised PNG images for size in parallel"
stdout " (Executes 'zopflipng' in parallel on the files specified as arguments.)"
stdout " Input files are overwritten."
stdout ""
stdout "Usage:"
stdout " $0 -h|-help|--help: Print this help message,"
stdout " $0 -V|-version|--version: Print this script's version,"
stdout " $0 [-j <n>] [zopflipng options] [--] [file(s)]:"
stdout " - Optional argument '-j <n>': Limit to max. '<n>' processes in parallel at the same time, must be the first argument and the number of processes must be separated by space. Default: Number of processing cores (`nproc`);"
stdout " - optional arguments '[zopflipng options]': Pass those options to 'zopflipng' (e.g. '-m', '--lossy_transparent', '--filters=0me', '--filters=b', '--filters=01234mepb' etc.);"
stdout " - argument(s) '[file(s)]': PNG files to optimise."
stdout ""
stdout " IMPORANT:"
stdout " If any 'zopflipng options' is set, the first one needs to start with '-', and the separator '--' between the zopflipng options and the files is mandatory."
}
_nproc="`nproc`"
_zopflipng_options=()
_files=()
_parsemode='none'
case "$1" in
'-V'|'-version'|'--version')
stdout "${VERSION}"
exit 0
;;
'-h'|'-help'|'--help')
printusage
exit 0
;;
'-j')
if [ "$#" -lt 2 ]; then
stderr "$0: Error: Option '-j' needs an argument."
stderr "Run '$0 -h' for help."
stderr "Aborting."
exit 1
fi
_nproc="$2"
shift
shift
;;
esac
case "$1" in
-*)
_parsemode=options
;;
*)
_parsemode=files
;;
esac
while [ "$#" -ge 1 ]; do
if [ "${_parsemode}" == "files" ]; then
_files+=("$1")
elif [ "${_parsemode}" == "options" ]; then
if [ "$1" == "--" ]; then
_parsemode="files"
else
_zopflipng_options+=("$1")
fi
fi
shift
done
#stdout "DEBUG: files:"
#stdout "${_files[@]}"
#stdout ""
#stdout "DEBUG: options"
#stdout "${_zopflipng_options[@]}"
#stdout "DEBUG: Would execute:"
#stdout "printf '%s\n' \"${_files[@]}\" | parallel -j \"${_nproc}\" zopflipng -y \"${_zopflipng_options[@]}\" {} {}"
# To make 'zopflipng' overwrite the input file, call it as 'zopflipng <inputfile> <inputfile>' (yes, same filename twice). To not ask for confirmation, use '-y' argument.
printf '%s\n' "${_files[@]}" | parallel -j "${_nproc}" zopflipng -y "${_zopflipng_options[@]}" {} {}
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