I know how to do every minute, but how about every 10 seconds?
You can't schedule the job every ten seconds, but I suppose you could schedule the job to run every minute, and sleep in a loop in 10s intervals. This would be predicated on your command being completed before the ten second interval expires, or you'll get overlap when the next command runs. This feels like a precarious solution, but if you can guarantee very short execution of the main command of the script, it would work.
#!/bin/bash i=0 while [ $i -lt 6 ]; do /run/your/command & sleep 10 i=$(( i + 1 )) done
I had a similar task last week. My solutions was to multiply the standard cron entries to the desired frequency. My crontab looks like:
* * * * * /usr/local/bin/php /var/www/myscript.php * * * * * sleep 10; /usr/local/bin/php /var/www/myscript.php * * * * * sleep 20; /usr/local/bin/php /var/www/myscript.php * * * * * sleep 30; /usr/local/bin/php /var/www/myscript.php * * * * * sleep 40; /usr/local/bin/php /var/www/myscript.php * * * * * sleep 50; /usr/local/bin/php /var/www/myscript.php
If you want to check results of myscript.php, e.g. for debugging, just append
to each line in the crontab above. Then stderr and stdout get redirected to the log file.
I'd use Monit and set the cycle time to 10 seconds. This is a clean way to manage this outside of the cron system.
I do this with certain scripts that need to run on a 15-second interval.
If you want to go sub 10 seconds, e.g. 5 second, I recommend to make a worker loop with a little script like that:
#!/bin/bash INTERVAL=5 while true; do echo "do something" # wait for next interval WAIT_UNTIL=$(($(date +%s) + $INTERVAL)) while [ $(date +%s) -lt $WAIT_UNTIL ]; do sleep 1 done done
If you need to go sub second, add microseconds to the date command.