bash argument case for args in $@

Question

I have a script with a long list of OPTIONAL arguments. some have associated values.

Such as:

.script --first 2012-12-25 --last 2012-12-26 --copy --remov         


        

Answer 1

You can allow both --a=arg or -a arg options with a little more work:

START_DATE="$(date '+%Y-%m-%d')";
LAST_DATE="$(date '+%Y-%m-%d')";
while [[ $# -gt 0 ]] && [[ "$1" == "--"* ]] ;
do
    opt="$1";
    shift;              #expose next argument
    case "$opt" in
        "--" ) break 2;;
        "--first" )
           START_DATE="$1"; shift;;
        "--first="* )     # alternate format: --first=date
           START_DATE="${opt#*=}";;
        "--last" )
           LAST_DATE="$1"; shift;;
        "--last="* )
           LAST_DATE="${opt#*=}";;
        "--copy" )
           COPY=true;;
        "--remove" )
           REMOVE=true;;
        "--optional" )
           OPTIONAL="$optional_default";;     #set to some default value
        "--optional=*" )
           OPTIONAL="${opt#*=}";;             #take argument
        *) echo >&2 "Invalid option: $@"; exit 1;;
   esac
done

Note the --optional argument uses a default value if "=" is not used, else it sets the value in the normal way.