Marti a 02:33, 12 gen 2017

2017-01-12T02:33:51Z

← Versió més antiga		Revisió del 02:33, 12 gen 2017
Línia 60:		Línia 60:
	22 4 * * 0 root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.weekly		22 4 * * 0 root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.weekly
	42 4 1 * * root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.monthly		42 4 1 * * root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.monthly
	<pre>		</pre>

Marti: Es crea la pàgina amb « ==Crontab format== crontab -e

 # For details see man 4 crontabs  # Example of job definition: # .---------------- minute (0 - 59) # |  .------------- hour (0 - 2...».

2017-01-12T02:33:08Z

Es crea la pàgina amb « ==Crontab format== crontab -e <pre> # For details see man 4 crontabs # Example of job definition: # .---------------- minute (0 - 59) # | .------------- hour (0 - 2...».

Pàgina nova

==Crontab format==
crontab -e
<pre>
# For details see man 4 crontabs

# 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

# m h dom mon dow user command
</pre>

== What executes /etc/cron.daily weekly monthly hourly ? ==

*'''crontab''' is running on memory
*'''anacron''' is run by periodically by crontab

*/etc/cron.hourly is run by crontab (anacron only has precision of days)

crontab runs cron.hourly which runs anacron which has /etc/anacron which run:
*/etc/cron.daily
*/etc/cron.weekly
*/etc/cron.monthly

In a new Ubuntu you can see in /etc/crontab (not visible for sudo crontab -e):
<pre>
# m h dom mon dow user command
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 )
#
</pre>

In Fedora there is a at /etc/cron.d/0hourly
<pre>
# Run the hourly jobs
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
01 * * * * root run-parts /etc/cron.hourly
</pre>

and in /etc/cron.d/dailyjobs
<pre>
# Run the daily, weekly, and monthly jobs if cronie-anacron is not installed
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# run-parts
02 4 * * * root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.daily
22 4 * * 0 root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.weekly
42 4 1 * * root [ ! -f /etc/cron.hourly/0anacron ] && run-parts /etc/cron.monthly
<pre>

==Cron vs Anacron==
{| class="wikitable"
! Cron !! Anacron
|-
| Minimum granularity is minute (i.e Jobs can be scheduled to be executed every minute) || Minimum granularity is only in days
|-
| Cron job can be scheduled by any normal user ( if not restricted by super user ) || Anacron can be used only by super user ( but there are workarounds to make it usable by normal user )
|-
| Cron expects system to be running 24 x 7. If a job is scheduled, and system is down during that time, job is not executed. || Anacron doesn’t expect system to be running 24 x 7. If a job is scheduled, and system is down during that time, it start the jobs when the system comes back up.
|-
| Ideal for servers || Ideal for desktops and laptops
|-
| Use cron when a job has to be executed at a particular hour and minute || Use anacron when a job has to be executed irrespective of hour and minute
|}

More info: http://www.thegeekstuff.com/2011/05/anacron-examples/

Cron - Historial de revisió

Marti a 02:33, 12 gen 2017

Marti: Es crea la pàgina amb « ==Crontab format== crontab -e
# For details see man 4 crontabs # Example of job definition: # .---------------- minute (0 - 59) # | .------------- hour (0 - 2...».