I have created a ruby script file that checks the connection present or not. For example checking port 22 is opened or not.

Firstly I tried with cron job as follows

@reboot find ${HOME}/my_app/check_conn.rb

But it is executing immediately after starting the system.

Now I have to run this script after 5 or 10 min.

How can I do this. Is there any other way for doing this.

Thanks in advance.

  • 2
    A bad hack: Add sleep 600; to the beginning of the command.
    – Dan
    Jul 2, 2014 at 16:31
  • I would never execute from cron itself and always create an executable file in /etc/cronjob; Just put an at command inside that file to execute it 5 minutes from now?
    – Rinzwind
    Jul 2, 2014 at 16:31
  • @dan08 did I have to add sleep 600; before my cron_job or in my script file? Jul 3, 2014 at 7:31
  • @dan08, please post your comment as an answer. Jul 3, 2014 at 7:45

2 Answers 2


Add sleep 600; to the beginning of your crontab command to make it wait for 600 seconds before proceeding to the next step.

Your new crontab command would look like

@reboot sleep 600; find ${HOME}/my_app/check_conn.rb


Don't do it depending on time, but after establishing a network connection. The right place to do it is below:


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