Add items to crontab: Difference between revisions

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(Removes superflous methods, removes reference to telnet since I don't believe this is even possible through telnet)
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== Background ==
== Background ==


==== Skills required ====
See [http://en.wikipedia.org/wiki/Cron Cron on Wikipedia]


You must be able to connect to your qnap using telnet and edit using vi.
=== Skills required ===


==== crontab ====
You must be able to connect to your qnap using [[SSH|SSH]] and edit [[Using_vi|using vi]].


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


To view the content of the crontab, login to your qnap using telnet and type:
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.
 
To view the content of the crontab, login to your qnap using ssh and type:
<pre>crontab -l
<pre>crontab -l
</pre>
</pre>
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You will see a (small) list of crontab entries.
You will see a (small) list of crontab entries.


Editing the crontab is also easy, on the console type:
<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>
<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


The crontab will be shown inside a vi session. Edit the crontab as you wish.
Once you have edited the crontab, execute the following to activate it:
<pre>/etc/init.d/crond.sh restart</pre>


See [http://en.wikipedia.org/wiki/Cron Cron on Wikipedia]


== Stock crontab jobs ==
== Stock crontab jobs ==
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== Method 1: /etc/config/crontab ==
== Adding/Changing cron entries ==


Edit /etc/config/crontab directly, then tell the cron service to reload the crontab. These changes will persist past a reboot so '''be careful!'''
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 / telnet'd into your nas (as admin).
Here is an example which assumes you are ssh'd into your nas (as admin).
<pre>echo "1 4 * * * /share/custom/scripts/custom1.sh" &gt;&gt; /etc/config/crontab
<pre>echo "1 4 * * * /share/custom/scripts/custom1.sh" >> /etc/config/crontab
echo "40 5 * * * /share/custom/scripts/custom2.sh" &gt;&gt; /etc/config/crontab
echo "40 5 * * * /share/custom/scripts/custom2.sh" >> /etc/config/crontab
crontab /etc/config/crontab</pre>
crontab /etc/config/crontab</pre>


== Method 2: autorun.sh ==
PS. Don't forget to make your scripts executable! Otherwise they will silently fail! You tested your script, right?
 
''Some peoples have reported this method as the working method and others have reported that this does not. Perhaps it is an outdated way to add cron jobs.''
 
<br/>Editing the crontab directly using 'crontab -e' as described above is possible on the QNAPs and it will function as expected. However as soon as your QNAP is restarted, you will be surprised to learn that all your custom entries will be gone from the crontab!
 
<br/>To prevent the loss of your work, use [[Autorun.sh|Autorun.sh]] or [http://www.qnap.box.cx/ AutoRunMaster] and a custom script for changing the crontab:
<pre>#!/bin/sh
# location: /share/custom/scripts/contab.sh
# script name: crontab script
# purpose: add entries to the crontab, which will survive a QNAP reboot
# designed for Qnap TS-201
tmpfile=/tmp/crontab.tmp
 
# read crontab and remove custom entries (usually not there since after a reboot
# QNAP restores to default crontab:
crontab -l | grep -vi "custom1.sh" | grep -vi "custom2.sh" &gt; $tmpfile
 
# add custom entries to crontab
echo "1 4 * * * /share/custom/scripts/custom1.sh" &gt;&gt; $tmpfile
echo "40 5 * * * /share/custom/scripts/custom2.sh" &gt;&gt; $tmpfile
 
#load crontab from file
crontab $tmpfile
 
# remove temporary file
rm $tmpfile
 
# restart crontab
/etc/init.d/crond.sh restart
</pre>
 
Make sure your script is called when the qnap is started by adding it to [[Autorun.sh|Autorun.sh]] or by using [http://www.qnap.box.cx/ AutoRunMaster]
 
 
 
== Method 1 bis:&nbsp; /etc/config/crontab, load and restart&nbsp; ==
 
In a post on&nbsp;[http://forum.qnap.com/viewtopic.php?f=144&t=32519&p=253371#p253371 http://forum.qnap.com/viewtopic.php?f=144&t=32519&p=253371#p253371]&nbsp;Micke writes&nbsp;:
 
 
 
Don't bother with that kind of script at all. Whenever you add a custom entry then follow this procedure
<blockquote>1. Edit /etc/config/crontab and add your custom entry.<br/>2. Run '/usr/bin/crontab /etc/config/crontab' to load the changes.&nbsp;<br/>3. Restart cron, i.e. '/etc/init.d/crond.sh restart'<br/></blockquote>
If you follow this procedure then the changes survive a reboot (even a firmware upgrade), i.e. no need for any script to restore them.
 
/Mike
 
PS.&nbsp;Don't forget to make your scripts executable&nbsp;! Otherwise they&nbsp;would not start!
<pre>chmod +x filename.sh</pre>
<pre>chmod +x filename.sh</pre>


Tested on 3.6.0&nbsp;: works fine.&nbsp;
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]]
[[Category:Adding new services]]

Revision as of 01:21, 28 July 2016

Background

See Cron on Wikipedia

Skills required

You must be able to connect to your qnap using SSH and edit using vi.

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.

To view the content of the crontab, login to your qnap using ssh and type: 

crontab -l

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

Do NOT edit the crontab in the usual way Normally you can 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 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.

Usually you will want to know, what default jobs are running on the QNAP based on schedule.

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 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/Changing cron entries

Edit /etc/config/crontab 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). 

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

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

chmod +x filename.sh

Tested on 3.6.0 : works fine.  Tested on 4.2.1 Freephile (talk) 01:21, 28 July 2016 (CST)

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