I want to verify that my cron job is executing and at what time. I believe there is a log for my sudo crontab -e jobs, but where?
I searched google and found recommendations to look in /var/log (in which I do not see anything with 'cron' in the name) and to edit the file /etc/syslog.conf which I also do not have.
On a default installation cron jobs will be logged to
/var/log/syslog
You can see just cron jobs in that logfile by running
grep CRON /var/log/syslog
If you haven't reconfigured anything, the entries will be in there.
You can create a cron.log file to contain just the CRON entries that show up in syslog. Note that CRON jobs will still show up in syslog if you follow the following directions.
Open the file
/etc/rsyslog.d/50-default.conf
Find the line that starts with:
#cron.*
uncomment that line, save the file, and restart rsyslog:
sudo service rsyslog restart
You should now see a cron log file here:
/var/log/cron.log
Cron activity will now be logged to this file (in addition to syslog).
Note that in cron.log you will see entries for when cron ran scripts in /etc/cron.hourly, cron.daily, etc. - e.g. something like:
Apr 12 14:17:01 cd CRON[14368]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
However, you will not see more information about what scripts were actually ran inside /etc/cron.daily or /etc/cron.hourly, unless those scripts direct output to the cron.log (or perhaps to some other log file).
If you want to verify if a crontab is running and not have to search for it in cron.log or syslog, create a crontab that redirects output to a log file of your choice - something like:
01 14 * * * /home/joe/myscript >> /home/log/myscript.log 2>&1
This will redirect all standard output and errors that may be produced by the script that is run to the log file specified.
Sometimes it can be useful to continuously monitor it, in that case:
tail -f /var/log/syslog | grep CRON
You can also direct the output of the individual cronjobs to their own logs for better readability, you will just need to append the output of date somewhere.
0 15 * * * /home/andrew/daily-backup.sh >> /var/log/daily-backup.log 2>&1
If you have systemd installed on your system, you could display cron job log by using the journalctl command.
For example, on my Ubuntu 17.10:
journalctl -u cron.service
journalctl -t CROND
on ubuntu >=18 it maybe
journalctl -t CRON
From the journalctl manual:
-t, --identifier=SYSLOG_IDENTIFIER|PATTERN
Show messages for the specified syslog identifier SYSLOG_IDENTIFIER,
or for any of the messages with a "SYSLOG_IDENTIFIER" matched by PATTERN.
This parameter can be specified multiple times.
This is a very old question, but none of these answers seem satisfactory.
First make your cron job run every minute, then run cron as non-daemon (temporarily, just kill any crond that may have already started) with test logging:
crond -nx test
And see the log of your program execution flowing through your terminal.
It is in /var/log/syslog by default.
But it can be set up to create a separate cron.log, which is more useful.
This Q&A describes the process:
16.04: How do I make cron create cron.log and monitor it in real time?
Also in this answer is the instructions to create a wcron command that displays it is near-real-time. Plus, it links to another answer,
that shows how to change the log level to include more than just the start of jobs - level 15 will show errors and end time, also.
Like mentioned earlier, cron jobs get logged to /var/log/syslog
You can pipe the syslog to grep and filter out the CRON logs, like this
less /var/log/syslog | grep CRON
You can search through your crontab logs, like this
less /var/log/syslog | grep CRON | grep <search-keyword-comes-here>
You can search through your crontab history logs stored in gz files, like this
less /var/log/syslog.2.gz | grep CRON | grep <search-keyword-comes-here>
Its always considered good to have a logging mechanism, you can quickly setup ELK for your servers, you can also experiment with logz .
On Ubuntu 20.04, /var/mail/{user} had the cron messages i was looking for.
I couldn't find decent cron logs in /var/log/messages.
Check all CRON related logs in syslog files included compressed log files as well like this way:
zless /var/log/syslog* | grep CRON
I found the current cron logs in /var/log/cron
and previous logs on /var/log/cron-date.
It may be different depending on the system type and edition. But in many cases, you have to figure out the time basis that the target crontab rule runs on. So for example, if you're searching for the related log for a daily crontab rule, then you'll find the log divided into different files, one per day, in:
$ ls -ltrh /var/log/cron-*
And you'll get the logfiles.
As said in this answer, by default cron jobs will be logged to
/var/log/syslog
So you can see cron jobs in that logfile by running
grep CRON /var/log/syslog
But, by default, /var/log/syslog is rotating daily, so grep will search only among records that are not older than 24 hours.
To grep all logs, including elder ones, you can use zgrep instead of grep this way:
zgrep CRON /var/log/syslog.*
It is strange but my cron is reporting into mail:
You have new mail in /var/mail/xerostomus
$ mail
Mail version 8.1.2 01/15/2001. Type ? for help.
"/var/mail/xerostomus": 6 messages 6 new
>N 1 root@localhost.lo Wed Sep 13 15:59 24/852 Cron <xerostomus@T430> env DISPLAY=:0 /home/xerostomus/idesk_cron.sh
By the way I am experimenting with Debian... :-)
If I need to log something in cron I use this simple task:
echo "cron report: variableA($variableA)" >> /dev/shm/grep.tmp
Not very smart, but works... :-)
sudo journalctl -f --system
This gives basic information that the cron works
Oct 19 18:57:01 ubuntu-01 CRON[10984]: pam_unix(cron:session): session opened for user root(uid=0) by root(uid=0)
Oct 19 18:57:01 ubuntu-01 CRON[10984]: (root) CMD ([10985] /usr/local/bin/script.sh >> /home/laborant/certscript.log 2>&1)
Oct 19 18:57:01 ubuntu-01 CRON[10984]: (root) END ([10985] /usr/local/bin/script.sh >> /home/laborant/certscript.log 2>&1)
Oct 19 18:57:01 ubuntu-01 CRON[10984]: pam_unix(cron:session): session closed for user root
