Let your script be named utstart, and accepts any of the following arguments: start, stop, install, uninstall.

As an example, you would perhaps run your script like this from bash:

./utstart start

You would like to autocomplete start, by pressing TAB key like this:

./utstart s[TAB]

This is easy.

Prerequisite:

Install bash-completion package.

apt-get install bash-completion

Now create a new script like this:

#!/bin/bash
_utstart()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="start stop install uninstall"

    if [[ ${cur} == * && ${COMP_CWORD} -eq 1 ]] ; then
        COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
        return 0
    fi
}
complete -F _utstart -o filenames utstart

Note that we have added the options “start stop install uninstall” in the script. Note also the last line contains the name of the function in our auto completion script, and also the name of our main bash script, which accepts autocompletion entries.

Once done, copy this file to /etc/bash_completion.d/utstart-auto.

Now you may change permissions on it to make it executable.

chmod +x /etc/bash_completion.d/utstart-auto

Source it with:

. /etc/bash_completion.d/utstart-auto

Now try the following:

./utstart s[TAB}

You will now be presented with start and stop as options.

Joel G Mathew

Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.

He is a full stack developer, whose favorite languages are currently Python and Vue.js. He is also fluent in Javascript, Flutter/Dart, Perl, PHP, SQL, C and bash shell scripting. He loves Linux, and can often be found tinkering with linux kernel code, and source code for GNU applications. He used to be an active developer on XDA forums, and his tinkered ROMS used to be very popular in the early 2000s.

His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.

When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.