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Command Parameters

commandline switches

*Tags*: command line parameters

How to handle command swithes in scripts. Here are the examples from the simplest to the most powerful one.

single switch (or in sequential order)

[ "x$1" = "x-l" ] && {
  log_url=T
  shift
  }

[ "x$1" = "x-t" ] && {
  file_title=$2
  shift 2
  }

optional command parameters

[ ${1+T} ] || fhelp
mto=$1
shift
mfm=$1
shift
[ ${1+T} ] && { msg=$1; shift; }

more than one switch in arbitrary order

while :; do
    case "$1" in
    -s*) fl_sys=T ;;  # system file listing
    -p*) shift; prefix="$1" ;;        # for the beg'ing of filename
    -s*) shift; surfix="$1" ;;        # for end of filename, bfr .tgz
    *)  break ;;
    esac
    shift
done

Many switch, any order, with parameters

use getopt, but really suggest using the previous method for compatibility reasons.

set -- `getopt "clhstx" "$@"` || fhelp

while :; do
    case "$1" in
    -s) fl_sys=T ;;   # system file listing
    -c) fl_csh=T ;;   # csh/tcsh system file listing
    -p*) shift; prefix="$1" ;;        # for the beg'ing of filename
    -t*) shift; surfix="$1" ;;        # for end of filename, bfr .tgz
    --) shift; break ;;
    esac
    shift
done

and can be called with combined switch such as '-sc..t'.

Meaningful Symbols

if [ "$1:+T" -a "$1" != "@"  ] ; then
  saved_name=$1
  shift
fi

documented on: 2004.07.10