im gonna reboot my server 6am every day, if my internet get disconnected and DDOSed. Does anyone have an idea how to do the command "at" at a specific time, and "AM"? Thanks- My computer clock doesnt have AM/PM, but I suppose linux wont understand if I write 06:00, will it be on mornings or on evenings?........

(I tried this for a test: echo "reboot" | at 23:17pm today), but it says "Unknown pm". What should i do?


  • Have you seen Ubuntu's Scheduled Tasks gui? – user29020 Jul 16 '14 at 19:09

You don’t need the PM because there is no 23:17am

Its a 24hr clock so just write it in 24hr format you cannot go wrong.

stephenm@mcr:~$ sudo at 6:00 tomorrow
[sudo] password for stephenm: 
warning: commands will be executed using /bin/sh
at> reboot
at> <ctrl+d>
job 4 at Sun Sep 22 06:00:00 2013

You most likely need crontab Logon to the server and type sudo crontab -e. In this instance, the root user will run the command at 6AM enter your password Select your preferred text editor - for example type 2 for nano. Create a new line on the bottom of the file and type * 6 * * * YOUR COMMAND HERE

Obviously replace YOUR COMMAND HERE with your command, however in your case this will be reboot

Exit and save The server will now reboot every 6AM

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