An introduction to bash completion

About.md

One of the nicest facilities of the modern shell is the built in "completion" support. These facilities allow you to complete commands and their arguments easily. Read on for a brief introduction to adding your own command completions. Most shells allow command completion, typically bound to the TAB key, which allow you to complete the names of commands stored upon your PATH, file names, or directory names. This is typically used like so:

  `ls /bo[TAB]`

When you press the TAB key the argument /bo is automatically replaced with the value /boot.

1. Install hdparm tool
2. Copy hdparm file to /etc/bash_completion.d/hdparm
3. Source this /etc/bash_completion.d/hdparm file using following command.

. /etc/bash_completion.d/hdparm 4. Now try hdparm command and check if auto completion is working or not.

Learn from here

hdparm

_hdparm()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="-a -A -b -B -c -C -d -D -E -f -F -g -h -H -i -I -J -k -K -L -m -M -n -N -p -P -q -Q -r -R -s -S -t -T -u -U -v -V -w -W -x -X -y -Y -z -Z --dco-freeze --dco-identify --dco-restore --direct --drq-hsm-error --fallocate --fibmap --fwdownload --fwdownload-mode3 --fwdownload-mode3-max --fwdownload-mode7 --idle-immediate --idle-unload --Istdin --Istdout --make-bad-sector --offset --prefer-ata12 --read-sector --security-help --trim-sector-ranges --trim-sector-ranges-stdin --verbose --write-sector --please-destroy-my-drive --yes-i-know-what-i-am-doing"

    case "${prev}" in
        -I|-i)
                local running=$(for x in `ls -1 /dev/sd*`; do echo ${x//} ; done)
                COMPREPLY=( $(compgen -W "${running}" -- ${cur}) )
                return 0
                ;;
        --please-destroy-my-drive)
                COMPREPLY=( $(compgen -W "--yes-i-know-what-i-am-doing" -- ${cur}) )
                return 0
                ;;
        --fwdownload|--fwdownload-mode3|--fwdownload-mode3-max|--fwdownload-mode7|--fibmap)
                local running=$(for x in `ls -1`; do echo ${x} ; done)
                COMPREPLY=( $(compgen -W "${running}" -- ${cur}) )
                return 0
                ;;
        *)
        ;;
    esac
    if [[ ${cur} == -* ]] ; then
        COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
        return 0
    fi
}
complete -F _hdparm hdparm