https://tanguy.ortolo.eu/blog/article150/shell-process-arguments en a blog about Debian and self-hosting Thu, 09 Jun 2016 08:36:00 +0000 PluXml https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465461360-1 https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465461360-1 @martin : Thank you for this example, you made me discover the column utility, and the possibility to use opening parentheses in case lists. I am not sure "${NEXT:-}" is any more useful than just "$NEXT" that should expand the same. Anyway, this mode of operation is good when you know exactly what options you will get, but not when you do not know but only want to operate (modify, remove, insert…) on some known options while keeping the other ones unmodified. Also, regarding the usage of getopt to process options with or without parameters, I personally use it this way, shifting the arguments instead of iterating over them, which removes the need for special handling of the next argument following an option that takes a parameter: eval set -- "$(getopt -o hw: --long help,wait: -- "$@")" while [ "$1" != "--" ] do case "$1" in -w|--wait) wait="$2"; shift 2 ;; -h|--help) usage ; exit 0 ;; esac done shift if [ $# -ne 1 ] ; then usage ; exit 1 ; fi file="$1" Thu, 09 Jun 2016 08:36:00 +0000 Tanguy https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465458927-1 https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465458927-1 How about using getopt? Here's something I wrote lately, which works rather well: usage() { echo "Usage: ${0##*/} [options] output-directory -- [git-annex filter]" cat <<-_eof | column -ts: --list, -l: output the list of files created --wipe, -w: wipe the target directory first --mode, -m: create copies, links, rellinks, or abslinks --get, -g: Obtain missing files from git-annex --visitor, -i: Include file for visitor pattern functions --help, -h: this message _eof echo echo " The git-annex filter defaults to '$DEFAULT_FILTER'" } WIPE=0 MODE=rellinks LIST=0 GET=0 OUTDIR= VISITOR= eval set -- $(getopt -o 'lm:wgi:h' -l 'list,mode:,wipe,get,visitor:,help' -n "${0##*/}" -s sh -- "$@") for opt; do case "${NEXT:-}" in ('') case "$opt" in (--list|-l) LIST=1;; (--wipe|-w) WIPE=1;; (--mode|-m) NEXT=mode;; (--get|-g) GET=1;; (--visitor|-i) NEXT=visitor;; (--help|-h) usage; exit 0;; (--) NEXT=outdir;; esac ;; (mode) MODE="$opt"; unset NEXT;; (outdir) OUTDIR="$opt"; NEXT=filter;; (filter) FILTER="${FILTER:+$FILTER }$opt";; (visitor) VISITOR="$opt"; unset NEXT;; esac done Thu, 09 Jun 2016 07:55:00 +0000 martin https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465392060-1 https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465392060-1 @Loïc Minier : You are welcome. Regarding your solution, rather than a while true with a break inside it, why not use a while [ $# -gt 0 ]? Also, when one needs to do several such list processing, it can be useful to define functions, as each shell function has its own "$@". I think I already used that at least once, not sure what for though. But then it becomes rather tricky anyway, so this is a point where one should start asking himself whether or not he should be using a regular programming language instead of shell scripting. Wed, 08 Jun 2016 13:21:00 +0000 Tanguy https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465389427-1 https://tanguy.ortolo.eu/blog/article150/shell-process-arguments/#c1465389427-1 Hey, Alternatively, you may also escape args and exec them as follows: escape() { echo "$*" | sed "s/'/'\"'\"'/g; s/.*/'&'/" } command="" while :; do command="$command $(escape "$1")" shift if [ $# -eq 0 ]; then break fi done break eval $command This basically serializes the args into a space separated array in a string using shell escape sequences. However I like your solution much more as it doesn't involve spawning external commands; I hadn't thought of reusing the positional args in my earlier shell scripts, thanks for sharing :-) Cheers, - Loïc Wed, 08 Jun 2016 12:37:00 +0000 Loïc Minier