launcher

#!/bin/sh -e
#
# launcher script for use with a menu program (e.g., dmenu, bemenu,
# fzf, etc.)
#
# launcher [utility [args...]]
#
# The command selected will be passed as an argument to the utility
# provided on this script's command line, e.g., "launcher i3-msg exec"
# to run under i3. If no utility is provided then the selected command
# will be ran directly by this script.
#
# The TERMCMD environment variable must be set in order to spawn a
# terminal for commands, e.g., "xterm -e" for xterm.
#
# The MENU environment variable determines the menu command to be used,
# defaults to "bemenu -i -l 10"
#

: "${TERMCMD:?'$TERMCMD must be set (i.e. xterm -e)'}"

# ensure $LAUNCHER_HISTORY is set and the file exists
: >> "${LAUNCHER_HISTORY:="${HOME:?}/.launcher"}"

cmd=$(sed '1!G;h;$!d' "$LAUNCHER_HISTORY" | ${MENU:-bemenu -i -l 10})

# XXX selecting an entry, Shift+Tab to copy it into the filter, and then
# C-A + Space to prepend it with a space should make it anonymous, but
# bemenu seems to strip the space in this case?
case "$cmd" in
	'') exit 0 ;;
	' '*) anonymous=1; cmd=${cmd#' '};;
	*) unset -v anonymous ;;
esac

case "$cmd" in
	[12]' '*) cmdctx=${cmd%%' '*}; cmd=${cmd#[12]' '} ;;
	*) unset -v cmdctx ;;
esac

if [ ! "$cmdctx" ]; then
	cmdctx=$(
		printf '%s\n' 'background' 'terminal' |
			${MENU:-bemenu -l 2 -p '' -P "Run '$cmd' in the"}
	)
	case "$cmdctx" in
		background) cmdctx=2 ;;
		terminal) cmdctx=1 ;;
		*) exit 1 ;;
	esac
fi

case "$cmdctx" in
	1) terminal=1 ;;
	*) unset -v terminal; cmdctx=2 ;;
esac

if [ ! "$anonymous" ]; then
		deduped=$(grep -Fxve "$cmdctx $cmd" -e "$cmd" < "$LAUNCHER_HISTORY") || :
		cat > "$LAUNCHER_HISTORY" <<-EOF
			$deduped
			$cmdctx $cmd
		EOF
fi

if [ "$*" ]; then
	exec "$@" "${terminal:+$TERMCMD }$cmd"
else
	eval exec "${terminal:+$TERMCMD }$cmd"
fi