shutdown -time directly while booting

[TobivanHernobi]

Hello,
I want to add a "shutdown -Ph time" right while/after booting. So I added a line in rc.local like "sudo shutdown -Ph 60". Unfortunately that doesn't work, in other words: the Raspi stops right at that line and doesn't do anything at all, just cursor-blinking.
So I tried to point at "/usr/local/shutdown_script.sh" which contains the shutdown command: same problem: booting hangs.
Any ideas? Thank you very much.

[RaTTuS]

in rc.local you don't need sudo as it is root anyway
you will also block anything else from happening
so
you also cannot login to a system that is being shutdown[within 5 mins]
so you need to think how long and exactly what oyu want to do

[TobivanHernobi]

I want to boot the Raspi which functions as a printing-server using CUPS. After let's say 5 hours (time=300) the Raspi should automatically power off. Next day it is being turned on via clock-timer (and then after booting plus 5 hours shutdown again and so on).

[DougieLawson]

Why not just leave it active? It costs £4.38 per year to run a Raspberry Pi at full load.

[TobivanHernobi]

That is not the question, please. Situation is as described.

[kusti8]

Add an & to the end of the shutdown script in rc.local.

[TobivanHernobi]

Thank you very much, kusti8