getopts positional parameter reordering hack

getopts_hack

#!/bin/sh -e
set -e

# Works mostly like built-in getopts but silently coalesces positional arguments.
# Does not take parameters. Set getopts_string prior to calling.
# Sets getopts_var and getopts_arg.
# $@ will be left with the positional arguments, so you should NOT shift at all.
# In bash, enables alias expansion until arguments are done being processed.
shopt -q -s expand_aliases 2>/dev/null || true
getopts_npos=0
getopts_dashdash=''
alias getopts_nextarg='getopts_ret=1
    while [ "$#" -gt "$getopts_npos" ]; do
        if [ -z "$getopts_dashdash" ] && getopts "$getopts_string" getopts_var; then
            if [ "$(($#+1-OPTIND))" -lt "$getopts_npos" ]; then
                # Bad parameter usage ate a positional argument.
                # Generate the proper error message by abusing getopts.
                set -- "-$getopts_var"
                getopts "$getopts_var:" getopts_var
                shift
            fi
            getopts_arg="$OPTARG"
            getopts_ret=0
            # Avoid -- confusion by shifting if OPTARG is set
            if [ -n "$OPTARG" ]; then
                shift "$((OPTIND-1))"
                OPTIND=1
            fi
            break
        fi
        # Do not let getopts consume a --
        if [ "$OPTIND" -gt 1 ]; then
            shift "$((OPTIND-2))"
            if [ "$1" != "--" ]; then
                shift
            fi
        fi
        OPTIND=1
        if [ -z "$getopts_dashdash" -a "$1" = "--" ]; then
            # Still need to loop through to fix the ordering
            getopts_dashdash=y
        else
            set -- "$@" "$1"
            getopts_npos="$((getopts_npos+1))"
        fi
        shift
    done
    if [ "$getopts_ret" = 1 ]; then
        shopt -q -u expand_aliases 2>/dev/null || true
    fi
    [ "$getopts_ret" = 0 ]'


# Test application.
# Try running this script using some of these parameters, positionals, and --'s
# Try using -- after a parameter that takes -- as an argument
# Try adding a trailing parameter
# Try combining parameters together into one multi-switch
getopts_string='a:bdef:k:m:M:n:p:P:r:s:t:T:uUV'
while getopts_nextarg; do
    echo "-$getopts_var $getopts_arg"
done
echo "$@"