manop.sh

#!/usr/bin/env bash

########################
# Author: Shinichi Okada
# Date: 2021-04-06
###########################

# set defaults
version="v0.1.3"
script_name=$(basename "$0")

usage() {
    cat <<EOF

Name:
=====
$script_name

Version:
=====
$version

Description:
=====
This script outputs a command description or an option description from the man page.

Usage:
======
$script_name [ -t | -h | -v][ command name ][ command option ]
    -t | --trim    Trim spaces
    -v | --version Show version
    -h | --help    Help

Examples:
=========
    Shows wget -b option description.
    $ manop wget -b

    Shows the ls command description.
    $ manop ls

    Shows builtin commands description.
    $ manop cd

    Shows builtin cd -e option description.
    $ manop cd -e

    Trim spaces
    $ manop -t grep -r

    To display builtin command help use help
    $ help cd

EOF
    exit 2
}

unset trim

case "$1" in
-t | --trim)
    trim=true
    shift
    ;;
-v | --version)
    echo $version
    exit 0
    ;;
-h | --help)
    usage
    exit 0
    ;;
esac

# find all builtin commands and decide the command name either
# man or help.
if type "$1" | grep -q "builtin"; then
    use=help
else
    use=man
fi

# help doesn't have Description nor empty lines after
# option description.
if [[ $use == "man" ]]; then
    if [[ $# -eq 2 ]]; then
        if [[ $trim == true ]]; then
            # If two args given, output the option description
            $use "$1" | col -bx | sed -n "/^  *$2/,/^$/p" | sed 's/  */ /g'
            exit 0
        else
            # If two args given, output the option description
            $use "$1" | col -bx | sed -n "/^  *$2/,/^$/p"
            exit 0
        fi
    else
        # otherwise display the command description
        if [[ $trim == true ]]; then
            $use "$1" | col -bx | sed -n '/^DESCRIPTION/,/^$/p' | sed 's/  */ /g'
            exit 0
        else
            $use "$1" | col -bx | sed -n '/^DESCRIPTION/,/^$/p'
        fi
    fi
else
    if [[ $# -eq 2 ]]; then
        if [ $trim = true ]; then
            # If two args given, output from the option description to the end of line since there is no empty lines in help outputs.
            $use "$1" | col -bx | sed -n "/^  *$2/,/$/p" | sed 's/  */ /g'
            exit 0
        else
            $use "$1" | col -bx | sed -n "/^  *$2/,/$/p"
            exit 0
        fi
    else
        if [[ $trim = true ]]; then
            # output from the first line to before Option
            $use "$1" | col -bx | sed '/Option/,$d' | sed 's/  */ /g'
            exit 0
        else
            $use "$1" | col -bx | sed '/Option/,$d'
            exit 0
        fi
    fi
fi