script to toggle visibility of a terminal

scratchpad.sh

#!/bin/sh

name="scratchpad"
class="URxvt"

# print the window id of the window with the given
# instance name as the first argument '$1' and
# class name as the second argument '$2'
get_win_id() {
	xwininfo -root -children -int | awk -v n="$1" -v c="$2" '$3 == "(\""n"\"" && $4 == "\""c"\")" { print $1 }'
}

# get the window id
winid="$(get_win_id "$name" "$class")"

# if the window was not found
if [ -z "$winid" ]
then
	# spawn it
	urxvt -name "$name"
	# get the window id again
	winid="$(get_win_id)"
	# if the window was not found then something is really wrong. give up.
	[ -z "$winid" ] && exit 1
fi

# if the window is hidden show it, else hide it
if ! xwininfo -id "$winid" | awk '$1 == "Map" && $2 == "State:" { exit ($3 == "IsUnMapped") }'
then xdotool windowmap   "$winid"
else xdotool windowunmap "$winid"
fi

Rxvt-unicode offers a daemon that handles client instances of urxvt.
The daemon is urxvtd and the clients are urxvtc.
Using the daemon/client scheme is much cheaper in terms of resource usage (mainly memory).

To use urxtvtc replace urxvt on line 22 with urxvtc.

Also check urxvtdc to safely spawn client instances of urxvt.