Ubuntu – Running command at startup on crontab

cron

I wanted to run a command on our linux after its done rebooting, I saw that it can be done using crontab. I wanted to run this command

sudo ifdown eth0 && sudo ifup -v eth0

on the crontab can i just do:

@reboot sudo ifdown eth0 && sudo ifup -v eth0

or do i need to store that in a script?

thank you

Best Answer

A few notes here before this would work:

  1. Don't use sudo in a cron job. Instead edit root's crontab instead of your own, e.g. sudo crontab -e and then enter commands without sudo.
  2. As @mikewhatever mentioned, this is an odd use for cron, and would likely be better placed in /etc/rc.local before the exit 0 line.
  3. If you tell us exactly what you're looking for, we might be able to direct you to a log or config option (restarting your network services at startup feels a little hackish).
  4. On most systems @reboot should also run after a hard shutdown or crash, but there are different cron implementations so YMMV. I've seen comments in different places asserting both.

EDIT (2016/02/17): Removed incorrect blurb on absolute paths; kudos @muru
EDIT (2016/10/17): Added shutdown note
EDIT (2017/09/11): Revised shutdown note. Not really sure on that one.

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