Reboot to an arbitrary UEFI entry

reboot.sh

#!/bin/bash
# Reboot-EFI (c) Karim Vergnes <me@thesola.io>
# Wrapper to reboot to a set UEFI entry
# Requires efibootmgr and fzy

rebootcmd="shutdown -r now"

trap _exit KILL INT TERM 

_exit() {
    exit 20
}

_get_bootcode()
{
    typeset -A entries
    local match
    local smatch

    if ! which -p efibootmgr >/dev/null 2>&1
    then
        >&2 echo "'efibootmgr' is missing, cannot proceed."
        exit 1
    fi

    {
        IFS=$'\n'

        for entry in $(efibootmgr | grep -iF "$1")
        do
            [[ "$entry" =~ Boot([0-9A-Fa-f]{4})(\*|\ )\ (.*) ]] &&\
                entries["${BASH_REMATCH[3]}"]="${BASH_REMATCH[1]}"
            match="${BASH_REMATCH[1]}"
            smatch="${BASH_REMATCH[3]}"
        done
    }
    
    if [[ ${#entries[@]} > 1 ]]
    then
        sel=$(printf '%s\n' "${!entries[@]}" | fzy)
        [[ ${#sel} == 0 ]] && exit 20   # fzy got killed

        >&2 echo "Rebooting to \`$sel'..."
        echo ${entries[$sel]}
    elif [[ ${#entries[@]} == 1 ]]
    then
        >&2 echo "Rebooting to \`$smatch'..."
        echo $match
    else
        >&2 echo "no target found for \`$1'"
        exit 1
    fi
}

_on_help()
{
    >&2 echo "usage: reboot [target]"
    exit 1
}


if [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]
then
    _on_help
fi

if [[ $# < 1 ]]
then
    exec $rebootcmd
elif [[ $# == 1 ]]
then
    bcode=$(_get_bootcode $1)
    [[ ${#bcode} == 0 ]] && exit 20     # no bootcode found

    efibootmgr -n $bcode >/dev/null 2>&1
    exec $rebootcmd
else
    _on_help
fi