A bash script which displays a pop-up showing a Steam activation key piped to it by a MUA.

steam-key-popup.sh

#/bin/bash

# Displays a pop-up showing a Steam activation key piped to it by a MUA.
# In the e-mail the steam key is wrapped in <h2> tags
# Author: Siôn Le Roux <sinisterstuf@gmail.com>

# read e-mail from pipe
while read -r line; do
    # find <h2>
    buffer=$(echo $line | grep 'h2')
    if [[ ! -z $buffer ]]; then
        #strip surrounding <h2> tags
        steamkey=$(echo $buffer | sed -e 's/<\/\?h2>//g')
    fi
done

# display the steam code in a pop-up
zenity --info --title="Steam Key" \
    --window-icon="/usr/share/pixmaps/steam.png" \
    --text="<tt><big><b>$steamkey</b></big></tt>"