Cron – How to create a cronjob that runs every 15 seconds

cron

It seems that Cron doesn't support a seconds interval. What is the easiest way to run a cli script (php) every 15 seconds? Is there a cron tool that works specifically with seconds (then I could use Cron to call it every minute)?

Best Answer

You need to write a shell script like this that sleeps on the specified interval and schedule that to run every minute in cron:

#!/bin/sh
# Script: delay_cmd
sleep $1
shift
$*

Then schedule that to run in cron with your parameters: delay_cmd 15 mycommand parameters

Related Solutions

How to Prevent Cron from Filling Up Syslog in Debian

You can send the output of cron to a separate log facility add the following to your /etc/syslog.conf file:

# Log cron stuff
cron.*                                                  /var/log/cron

Remember to add /var/log/cron to your /etc/logrotate.d/syslog to ensure it gets rotated, eg

# /etc/logrotate.d/syslog
/var/log/messages /var/log/secure /var/log/maillog /var/log/spooler /var/log/boot.log /var/log/cron {
    sharedscripts
    postrotate
    /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

Cron – How to Prevent Duplicate Cron Jobs Running

There are a couple of programs that automate this feature, take away the annoyance and potential bugs from doing this yourself, and avoid the stale lock problem by using flock behind the scenes, too (which is a risk if you're just using touch). I've used lockrun and lckdo in the past, but now there's flock(1) (in newish versions of util-linux) which is great. It's really easy to use:

* * * * * /usr/bin/flock -n /tmp/fcj.lockfile /usr/local/bin/frequent_cron_job

Best Answer

Related Solutions

How to Prevent Cron from Filling Up Syslog in Debian

Cron – How to Prevent Duplicate Cron Jobs Running

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