CronJob not running

Question

I have set up a cronjob for root user in ubuntu environment as follows by typing crontab -e

  34 11 * * * sh /srv/www/live/CronJobs/daily.sh
  0          


        

Answer 1

Finally I found the solution. Following is the solution:-

1. Never use relative path in python scripts to be executed via crontab. I did something like this instead:-

   import os
   import sys
   import time, datetime
   
   CLASS_PATH = '/srv/www/live/mainapp/classes'
   SETTINGS_PATH = '/srv/www/live/foodtrade'
   sys.path.insert(0, CLASS_PATH)
   sys.path.insert(1,SETTINGS_PATH)
   
   import other_py_files
   

2. Never supress the crontab code instead use mailserver and check the mail for the user. That gives clearer insights of what is going.

Answer 2

It might also be a timezone problem.

Cron uses the local time.

Run the command timedatectl to see the machine time and make sure that your crontab is in this same timezone.

• https://askubuntu.com/a/536489/1043751

Answer 3

Another reason crontab will fail: Special handling of the % character.

From the man file:

The entire command portion of the line, up to a newline or a
"%" character, will be executed by /bin/sh or by the shell specified
in the SHELL variable of the cronfile.  A "%" character in the
command, unless escaped with a backslash (\), will be changed into
newline characters, and all data after the first % will be sent to
the command as standard input.

In my particular case, I was using date --date="7 days ago" "+%Y-%m-%d" to produce parameters to my script, and it was failing silently. I finally found out what was going on when I checked syslog and saw my command was truncated at the % symbol. You need to escape it like this:

date --date="7 days ago" "+\%Y-\%m-\%d"

See here for more details:

http://www.ducea.com/2008/11/12/using-the-character-in-crontab-entries/

Answer 4

To add another point, a file in /etc/cron.d must contain an empty new line at the end. This is likely related to the response by Luciano which specifies that:

The entire command portion of the line, up to a newline or a "%"
character, will be executed

Answer 5

Sometimes the command that cron needs to run is in a directory where cron has no access, typically on systems where users' home directories' permissions are 700 and the command is in that directory.

Answer 6

I've found another reason for user's crontab not running: the hostname is not present on the hosts file:

user@ubuntu:~$ cat /etc/hostname
ubuntu

Now the hosts file:

user@ubuntu:~$ cat /etc/hosts
127.0.0.1 localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

This is on a Ubuntu 14.04.3 LTS, the way to fix it is adding the hostname to the hosts file so it resembles something like this:

user@ubuntu:~$ cat /etc/hosts
127.0.0.1 ubuntu localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts