Comment 2 for bug 163810

Thanks for taking the time to report this bug and helping to make Ubuntu better. As I understand the problem, this is correct behavior from "at", though perhaps the problem is that the error reports aren't being delivered to you. (Is local email delivery configured?) Check /var/mail for at errors.

Issues:
 1) at runs like cron, it does not have your Xorg environment and cannot launch X applications without additional scripting, etc
 2) running /bin/sh /usr/games/glchess won't work (and isn't what at does), since you're forcing it to interpret the script as a shell script (it's not). when at runs, it uses sh for spawning shells (and will correctly execute scripts of any type), the warning is there to remind about the reduced environment and capabilities