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rt-n56u / EN / UsingCron

Using cron

This firmware has built-in cron daemon which can be handy to run scheduled jobs (periodically).

  • Go to Administration > Services WebUI page,
  • Turn on Cron Daemon (Scheduler)? switch,
  • Edit Scheduler tasks (Crontab) field,
  • Press Apply.

Crontab field has the following syntax:

00 06 * * * ether-wake -i br0 XX:XX:XX:XX:XX:XX

where 00 06 * * * is the time to execute job (equals to "run every day at 06:00AM"), ether-wake -i br0 XX:XX:XX:XX:XX:XX is the command to execute (wake up some PC with XX:XX:XX:XX:XX:XX MAC address). You can find details here.


Note

Please note, this daemon inherits $PATH variable from firmware (without /opt/bin or /opt/sbin), so you have to place full path to every executable outside of firmware. To avoid this, use shell wrapper /etc/storage/cron/shell-wrapper.sh:

#!/bin/sh

# Pull $PATH and other settings from /etc/profile and /opt/etc/profile
. /etc/profile

# Shell keywords shouldn't have a "-c" prefix
[ "$1" = "-c" ] && shift

# Call cron job
SHELL=/bin/sh eval $@

Make it executable:

chmod +x /etc/storage/cron/shell-wrapper.sh

and place following string on top of crontab field:

SHELL=/etc/storage/cron/shell-wrapper.sh

Thanks to @Vladislav Grishenko for debugging shell wrapper script.

Updated