shutdown-dialog

#!/bin/bash
set -euo pipefail

# shutdown-dialog
# Prompt for shutdown/restart, similar to Gnome 2 poweroff dialog


usage() {
    cat >&2 <<EOM
usage: $(basename "$0") OPTIONS

Print an interactive dialog for initiating shut down or reboot of the computer.

DBUS is used to send the shutdown/reboot signal, so sudo is not needed in a
typical desktop setting. This can be run as a normal user.

Options:

    -h, --help      Print this message
    -p, --prompt    Show dialog and maybe shutdown computer
    -i, --install   Install this script in /usr/local/bin/
    --install-shortcuts    Update keyboard shortcuts


For example:

    $(basename "$0") --prompt


If --install-shortcuts is given, update Gnome keyboard shortcuts with the
following:

    logout      win + shift + q     (default ctrl + alt + del)
    shutdown    ctrl + alt + del    (no default)
    dialog      win + alt + del     (no default)
    dialog      ctrl + win + del    (no default)

All three are dialogs with confirmation. logout/shutdown use the built-in
gnome-session-quit, whereas dialog uses this script.

EOM
}


run() {
    echo >&2 "+ $*"
    "$@"
}


# Prompt for shutdown
# Prints "cancel" | "reboot" | "shutdown" to stdout
prompt_shutdown_actions() {
    local ret out
    out="$(
        zenity --warning \
            --icon-name=system-shutdown --title='' --ok-label='Cancel' \
            --extra-button='Reboot' --extra-button='Shutdown' \
            --text='Shut down this system now?'
    )" && ret=$? || ret=$?

    if [ "$ret" -eq 0 ]; then
        # We relabeled the OK button as Cancel to get button order right
        echo "cancel"
        return
    fi


    if [ "$ret" -eq 1 ]; then
        case "$out" in
            "")
                echo "cancel"
                return
                ;;
            "Reboot")
                echo "reboot"
                return
                ;;
            "Shutdown")
                echo "shutdown"
                return
                ;;
            *)
                echo >&2 "Unexpected Zenity stdout: '$out'"
                return 2
                ;;
        esac
    else
        echo >&2 "Unexpected status $ret from zenity"
        return 3
    fi
}


dbus_reboot() {
    run dbus-send --system --print-reply --dest=org.freedesktop.login1 \
        /org/freedesktop/login1 "org.freedesktop.login1.Manager.Reboot" boolean:true
}


dbus_poweroff() {
    run dbus-send --system --print-reply --dest=org.freedesktop.login1 \
        /org/freedesktop/login1 "org.freedesktop.login1.Manager.PowerOff" boolean:true
}


prompt_and_shutdown() {
    local ans

    ans="$(prompt_shutdown_actions)"
    case "$ans" in
        "cancel")
            echo "cancel"
            return
            ;;
        "reboot")
            echo "reboot"
            dbus_reboot
            ;;
        "shutdown")
            echo "shutdown"
            dbus_poweroff
            ;;
        *)
            echo >&2 "Unexpected ans from prompt_shutdown_actions: $ans"
            return 1
    esac
}


install_script() {
    set -x
    sudo cp -v --preserve=timestamps "$0" /usr/local/bin/
}


# usage: $0 NAME
# Find the custom hotkey in dconf with the given name
#
# Note: NAME must contain literal ' characters, as in
#   find_custom_hotkey "'foo'"
#
find_custom_hotkey() {
    local target_name

    if [ $# -ne 1 ]; then
        echo >&2 "Must pass exactly 1 desired hotkey name"
        return 1
    fi
    target_name="$1"

    local dconf_dir
    dconf_dir=/org/gnome/settings-daemon/plugins/media-keys/custom-keybindings

    local id
    for id in $(dconf list "$dconf_dir/"); do
        id="${id%/}"  # strip trailing /
        name="$(dconf read "$dconf_dir/$id/name")"

        if [ "$name" = "$target_name" ]; then
            echo >&2 "Found existing custom hotkey id=$id name=$name"
            echo "$id"
            return
        fi
    done

    # exit 0 whether we found something or not
}


# usage: dconf_write_if_needed KEY VALUE
# Read current value of KEY. If it differs from VALUE, set it, and echo that we
# did so.
#
# Note that VALUE should contain literal ' characters if it's a string, as in:
#
# dconf_write_if_needed /foo/bar/ "'string'"
#
dconf_write_if_needed() {
    if [ $# -ne 2 ]; then
        echo >&2 "dconf_write_if_needed takes 2 args"
        return 1
    fi
    local key desired_val current
    key="$1"
    desired_val="$2"

    current="$(dconf read "$key")"
    if [ "$current" != "$desired_val" ]; then
        run dconf write "$key" "$desired_val"
    fi
}


# Usage: set_custom_hotkey NAME DEFAULT_ID BINDING COMMAND
#
# Set or update a custom hotkey using dconf
#
# NAME          User-visible label for the hotkey
# DEFAULT_ID    Default ID in dconf for creating new hotkey, must be unique
# BINDING       Hotkeys to press
# COMMAND       Command to run
#
set_custom_hotkey() {
    if [ $# -ne 4 ]; then
        echo >&2 "set_custom_hotkey: bad usage -- takes 4 args"
        return 1
    fi
    local name default_id binding cmd
    name="$1"
    default_id="$2"
    binding="$3"
    cmd="$4"

    # name, binding, command all get wrapped in ' since they are strings in
    # dconf
    name="'$name'"
    binding="'$binding'"
    cmd="'$cmd'"

    local custom_dir=/org/gnome/settings-daemon/plugins/media-keys/custom-keybindings

    # find custom hotkey matching our target name, if any
    id="$(find_custom_hotkey "$name")"

    if [ -z "$id" ]; then
        # If ID is empty, we're creating a new custom command
        id="$default_id"
        run dconf write "$custom_dir/$id/name" "$name"

        # add our ID to the list as well
        local schema custom_list new_list
        schema=org.gnome.settings-daemon.plugins.media-keys
        custom_list="$(gsettings get "$schema" custom-keybindings)"

        # handle empty list
        if [ "$custom_list" = '@as []' ]; then
            new_list="['$custom_dir/$id/']"
        else
            # append
            # strip trailing "]" and add ",'/newpath/']" (yes, this is horrendous)
            new_list="${custom_list%]},'$custom_dir/$id/']"
        fi
        run gsettings set "$schema" custom-keybindings "$new_list"
    fi

    # get/create binding and command
    dconf_write_if_needed "$custom_dir/$id/binding" "$binding"
    dconf_write_if_needed "$custom_dir/$id/command" "$cmd"
}


install_shortcuts() {
    # logout      win + shift + q
    # shutdown    ctrl + alt + del
    # dialog      win + alt + del

    # set logout, as needed
    dconf_write_if_needed \
        /org/gnome/settings-daemon/plugins/media-keys/logout "['<Shift><Super>q']"


    # shutdown    ctrl + alt + del
    set_custom_hotkey 'Shutdown' 'custom-shutdown' \
        '<Primary><Alt>Delete' "gnome-session-quit --power-off"

    # dialog      win + alt + del
    set_custom_hotkey "Custom Shutdown Dialog" 'custom-agb-shutdown' \
        '<Alt><Super>Delete' '/usr/local/bin/shutdown-dialog --prompt'
    # dialog      ctrl + win + del
    set_custom_hotkey "Custom Shutdown Dialog 2" 'custom-agb-shutdown-2' \
        '<Primary><Super>Delete' '/usr/local/bin/shutdown-dialog --prompt'

    echo "All done."

    if [ ! -x /usr/local/bin/shutdown-dialog ]; then
        echo >&2 "WARNING: /usr/local/bin/shutdown-dialog does not exist or not executable"
        echo >&2 "May need to call this script with --install"
    fi
}


if [ $# -ne 1 ]; then
    usage
    exit 1
fi

case "$1" in
    -h|--help)
        usage
        exit
        ;;
    -p|--prompt)
        prompt_and_shutdown
        ;;
    -i|--install)
        install_script
        ;;
    --install-shortcuts)
        install_shortcuts
        ;;
    *)
        echo >&2 "Invalid option $1"
        usage
        exit
        ;;
esac