Correct way to edit cron jobs?

[thomas-hn]

Hi,

what is the correct way to edit cron jobs on the Proxmox host?
In the file "/etc/crontab" I can see some default content:

root@pve:~# cat /etc/crontab
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name command to be executed
17 *    * * *   root    cd / && run-parts --report /etc/cron.hourly
25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

But if I execute "crontab -e" there is only:

# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').
#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
#
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h  dom mon dow   command

So what is the correct way to add own cron jobs?
And do I need to restart cron at the end? For example, via:

/etc/init.d/cron restart

Thanks a lot in advance,

Thomas

 

[Lukas Wagner]

Hello,

I'd go with crontab -e. You don't need to restart cron afterwards [0].

[0] https://serverfault.com/questions/3...ything-after-i-add-update-a-crontab-in-ubuntu

PS: For questions like these you can also try to look up how things are done on Debian, since Proxmox VE is just that under the hood

Hope this helps,

 

[thomas-hn]

I'd go with crontab -e. You don't need to restart cron afterwards [0].

Thanks for your clarification.
However, what I still don't understand is, why I see some jobs in "/etc/crontab" which are not shown when running "crontab -e".

 

[Lukas Wagner]

However, what I still don't understand is, why I see some jobs in "/etc/crontab" which are not shown when running "crontab -e".

/etc/crontab is the system-wide crontab, whereas crontab -e alters the crontab of the user currently running the command. They will be stored in /var/spool/cron/crontabs/<username>.

One benefit of using crontab -e to edit is that the command will validate the syntax of the file before it is saved.