Add items to crontab: Difference between revisions

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=== crontab ===
=== crontab ===


The crontab can be used to execute tasks (scripts) based on a recurring schedule; by default the crontab is used, for example, to restart the webserver during the night.
The crontab can be used to execute tasks (scripts) based on a recurring schedule. The crontab is used, for example, to restart the webserver during the night.


To view the content of the crontab, login to your qnap using ssh and type:
To view the content of your crontab, login to your QNAP via SSH and type:
<pre>crontab -l
<pre>crontab -l
</pre>
</pre>


You will see a (small) list of crontab entries.
You will see a (small) list of crontab entries.
<span style="color:red">Do NOT edit the crontab in the usual way</span> Normally you can edit a user's crontab with
<pre>crontab -e</pre>
However, due to the way the QNAP firmware updates crontab, it will be '''overwritten''' on the next reboot. Obviously you want your automation to survive reboots, so read the section below on how to modify and persist changes to cron on QNAP




== Stock crontab jobs ==


When using crontab -l on a default QNAP, QNAPs has some default crontab jobs.
== Standard crontab jobs ==


Usually you will want to know, what default jobs are running on the QNAP based on schedule.
The following table contains the standard QNAP jobs that run on schedules.


The following table is meant to bring some light into those built-in jobs.The list is by no means complete, jobs may depend on the firmware version, start times may vary. If you find a job on your QNAP, that is missing in the table, add it. The list could help to identify unwanted jobs on the QNAP&nbsp;that regularly wake up your harddisk(s).
This list is by no means complete. Jobs may depend on the firmware version, start times may vary. If you find a job on your QNAP, that is missing from the table, add it. The list could help to identify unwanted jobs that regularly wake up your harddisk(s).


{| cellspacing="1" cellpadding="1" border="1" width="100%"
{| cellspacing="1" cellpadding="1" border="1" width="100%"
Line 38: Line 31:
! scope="col" | Explanation<br/>
! scope="col" | Explanation<br/>
|-
|-
| 0 4 * * *
| 0 4 * * *<br/>
| /sbin/hwclock -s
| /sbin/hwclock -s
| [http://linux.die.net/man/8/hwclock http://linux.die.net/man/8/hwclock]<br/>
| [http://linux.die.net/man/8/hwclock http://linux.die.net/man/8/hwclock]<br/>
Line 46: Line 39:
| vs_refresh is for share folder space usage calculation (for Network Share Management)<br/>
| vs_refresh is for share folder space usage calculation (for Network Share Management)<br/>
|-
|-
| 0 3 * * 0
| 0 3 * * 0<br/>
| /etc/init.d/idmap.sh dump
| /etc/init.d/idmap.sh dump
| related to SAMBA Active Directory configuration. Used if security is set to ADS.<br/>
| related to SAMBA Active Directory configuration. Used if security is set to ADS.<br/>
|-
|-
| 0 3 * * *
| 0 3 * * *<br/>
| /sbin/clean_reset_pwd
| /sbin/clean_reset_pwd
| (unclear) might be the new behaviour of the network recycle bin (purging files after a certain amount of days)<br/>
| (unclear) might be the new behaviour of the network recycle bin (purging files after a certain amount of days)<br/>
|-
|-
| 0-59/15 * * * *
| 0-59/15 * * * *<br/>
| /etc/init.d/nss2_dusg.sh
| /etc/init.d/nss2_dusg.sh
| is a job of the Surveillance Station<br/>
| is a job of the Surveillance Station<br/>
Line 93: Line 86:




== Adding/Changing cron entries ==
== Adding entries at the command-line ==
Here are a couple of examples that append new entries to the crontab file:<pre>echo "1 4 * * * /share/custom/scripts/custom1.sh" >> /etc/config/crontab
echo "40 5 * * * /share/custom/scripts/custom2.sh" >> /etc/config/crontab</pre>
 
 
 
== Modifying entries ==
 
'''<span style="color:red">Do NOT edit crontab the usual way!</span>'''
 
On a desktop or server distribution, you would edit a user's crontab with:
<pre>crontab -e</pre>
 
However, due to the way the QNAP firmware updates crontab, it will be '''overwritten''' on the next reboot. Obviously, you want your automation to survive reboots, so edit the crontab file directly with your text editor:
<pre>vi /etc/config/crontab</pre>
 
or
<pre>nano /etc/config/crontab</pre>
 
 
 
== Restart the daemon ==
 
When you're done, reload the crontab file and restart the cron daemon:
<pre>crontab /etc/config/crontab && /etc/init.d/crond.sh restart</pre>


Edit <code>/etc/config/crontab</code> directly, then tell the cron service to reload the crontab. These changes will persist past a reboot. Like any changes to cron, you should test your script thoroughly before adding it.


Here is an example which assumes you are ssh'd into your nas (as admin).
<pre>echo "1 4 * * * /share/custom/scripts/custom1.sh" >> /etc/config/crontab
echo "40 5 * * * /share/custom/scripts/custom2.sh" >> /etc/config/crontab</pre>


Then reload crontab and restart cron daemon:
== Notes ==
<pre>crontab /etc/config/crontab
/etc/init.d/crond.sh restart</pre>


PS. Don't forget to make your scripts executable! Otherwise they will silently fail! You tested your script, right?
Don't forget to make your scripts executable! Otherwise they will silently fail! You tested your script, right?
<pre>chmod +x filename.sh</pre>
<pre>chmod +x filename.sh</pre>


Tested on 3.6.0&nbsp;: works fine.&nbsp; Tested on 4.2.1 [[User:Freephile|Freephile]] ([[User_talk:Freephile|talk]]) 01:21, 28 July 2016 (CST)
 
[[Category:Adding new services]]
<div><span style="font-size:smaller">''These instructions have been tested on various versions of QNAP firmware from 3.6.0 onwards.''</span><br/></div> [[Category:Adding new services]]

Latest revision as of 16:49, 12 December 2016

Background

See Cron on Wikipedia

Skills required

You must be able to connect to your QNAP device using SSH and edit using a text editor such as vi or nano.

crontab

The crontab can be used to execute tasks (scripts) based on a recurring schedule. The crontab is used, for example, to restart the webserver during the night.

To view the content of your crontab, login to your QNAP via SSH and type:

crontab -l

You will see a (small) list of crontab entries.


Standard crontab jobs

The following table contains the standard QNAP jobs that run on schedules.

This list is by no means complete. Jobs may depend on the firmware version, start times may vary. If you find a job on your QNAP, that is missing from the table, add it. The list could help to identify unwanted jobs that regularly wake up your harddisk(s).

Default Time
Job
Explanation
0 4 * * *
/sbin/hwclock -s http://linux.die.net/man/8/hwclock
0 3 * * * /sbin/vs_refresh vs_refresh is for share folder space usage calculation (for Network Share Management)
0 3 * * 0
/etc/init.d/idmap.sh dump related to SAMBA Active Directory configuration. Used if security is set to ADS.
0 3 * * *
/sbin/clean_reset_pwd (unclear) might be the new behaviour of the network recycle bin (purging files after a certain amount of days)
0-59/15 * * * *
/etc/init.d/nss2_dusg.sh is a job of the Surveillance Station
10 15 * * * /usr/bin/power_clean -c 2>/dev/null  ?
4 3 * * 3 /etc/init.d/backup_conf.sh does an automatic backup of several config files in /etc/config.
0 3 * * *
/bin/rm -rf /mnt/HDA_ROOT/twonkymedia/twonkymedia.db/cache/*
Will clear the Twonky media cache
5 0 * * 1
/etc/init.d/antivirus.sh scan 1
If Antivirus is enabled, this will scan the files for viruses
0 0 * * *
/etc/init.d/antivirus.sh archive_log
If Antivirus report jobs are enabled
0 0 */1 * *
/etc/init.d/antivirus.sh update_db
If Antivirus is enabled, this will check  clamav.net for updates

/etc/init.d/startup
If a restart/powerof job is configured in power management

/etc/init.d/poweroff
If a restart/powerof job is configured in power management


Adding entries at the command-line

Here are a couple of examples that append new entries to the crontab file:

echo "1 4 * * * /share/custom/scripts/custom1.sh" >> /etc/config/crontab
echo "40 5 * * * /share/custom/scripts/custom2.sh" >> /etc/config/crontab


Modifying entries

Do NOT edit crontab the usual way!

On a desktop or server distribution, you would edit a user's crontab with:

crontab -e

However, due to the way the QNAP firmware updates crontab, it will be overwritten on the next reboot. Obviously, you want your automation to survive reboots, so edit the crontab file directly with your text editor:

vi /etc/config/crontab

or

nano /etc/config/crontab


Restart the daemon

When you're done, reload the crontab file and restart the cron daemon:

crontab /etc/config/crontab && /etc/init.d/crond.sh restart


Notes

Don't forget to make your scripts executable! Otherwise they will silently fail! You tested your script, right?

chmod +x filename.sh


These instructions have been tested on various versions of QNAP firmware from 3.6.0 onwards.