source: utils/Bash/bash_completion@ c42a43

# bash_completion for molecuilder 
#
# gives a list of all available actions, gives list of options for the last action

function _molecuilder_option()
{
        local cmd="${1##*/}"
        local word=${COMP_WORDS[COMP_CWORD]}
        local line=${COMP_LINE}
        option=`echo $line | awk -F"--" {'print $NF'} | tr -d \ `
        previousoption=`echo $line | awk -F"--" {'print $(NF-1)'} | tr -d \ `
        #echo "current option is '$word', line is '$line', and cmd is '$cmd', last option is '$option', and last but one is '$previousoption'."
        COMPREPLY=()
        # if current option is molecuilder, give all available actions
        if test x"$option" = x"molecuilder"; then
                # "molecuilder "
                COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
        else
                # if current argument is void, look at previous (if its not molecuilder)
                if test x"$option" = x""; then
                        if test x"$previousoption" = x"molecuilder"; then
                                # "molecuilder --"
                                COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                        else
                                # "molecuilder --some-action --"
                                COMPREPLY=($($cmd --help | grep "^'$previousoption.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                if  test ${#COMPREPLY[*]} -eq 0; then
                                        # "molecuilder --some-option --"
                                        COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                else
                                        COMPREPLY=($($cmd --help --actionname "$previousoption" | grep Option\  | awk -F"'" {'print "--"$2'} | tr -d \'))
                                        # if action has no options, give list of actions
                                        if  test ${#COMPREPLY[*]} -eq 0; then
                                                COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                        fi
                                fi
                        fi
                elif test -z `echo "$word" 2>/dev/null | grep "\-\-"`; then
                        # "molecuilder somefile/value"
                        COMPREPLY=( $( compgen -W "$( ls --color=n -1 ${word}*.in ${word}*.pdb ${word}*.pcp ${word}*.psi ${word}*.data ${word}*.xyz 2>/dev/null| sed -e 's/ /\\ /g' )" -- $cur ))
                else
                        # "molecuilder --something"
                        COMPREPLY=($($cmd --help | grep "^'$option.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                        # check whether its an action
                        if test ${#COMPREPLY[*]} -eq 1; then
                                # check whether it's same as option
                                if test x"${COMPREPLY[0]}" = x"--$option"; then
                                        # "molecuilder --an-action"
                                        #echo "Giving help for option $option"
                                        COMPREPLY=($($cmd --help --actionname "$option" | grep Option\  | awk -F"'" {'print "--"$2'} | tr -d \'))
                                        # if action has no options, give list of actions
                                        if  test ${#COMPREPLY[*]} -eq 0; then
                                                COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                        fi
                                fi
                        fi
                        # if the "action" is unknown, it must be actually an option (segment), give all available options from previous action
                        if test ${#COMPREPLY[*]} -eq 0; then
                                # "molecuilder --an-action --opt.."
                                COMPREPLY=($($cmd --help --actionname "$previousoption" | grep Option\ | grep $option | awk -F"'" {'print "--"$2'} | tr -d \'))
                                # if action has no options, give list of actions
                                if  test ${#COMPREPLY[*]} -eq 0; then
                                        COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                else
                                        #if we have a complete option, give again all available actions
                                        if test x"${COMPREPLY[0]}" = x"--$option"; then
                                                # "molecuilder --an-action --one-of-its-options"
                                                COMPREPLY=($($cmd --help | grep "^'.*'" | awk -F":" {'print "--"$1'} | tr -d \'))
                                        fi
                                fi
                        fi
                fi
        fi
        #echo "returning ${COMPREPLY[*]}."
        return 0
}

complete -F _molecuilder_option molecuilder