Log of cron actions on OS X

Question

Does the cron which comes with OS X log its actions anywhere?

I'm not looking for output of any particular cron job, but rather log of what cron is doing. On a couple linux machines I've checked, there's /var/log/cron which has contents like:

Apr 26 11:00:01 localhost crond[27755]: (root) CMD (/root/bin/mysql-backup)
Apr 26 11:01:01 localhost crond[27892]: (root) CMD (run-parts /etc/cron.hourly)
Apr 26 11:07:01 localhost crond[28138]: (root) CMD (/usr/local/bin/python /home/
user1/scripts/pythonscript.py)
Apr 26 11:18:18 localhost crontab[28921]: (user2) LIST (user2)
Apr 26 11:18:22 localhost crontab[28929]: (user2) BEGIN EDIT (user2)
Apr 26 11:18:59 localhost crontab[28929]: (user2) REPLACE (user2)

This shows when jobs ran, when users viewed or edited crontabs, etc. This stuff is nowhere that I've found on my Snow Leopard machine.

Answer 1

I figured it how to log my cron job activity without switching each one over to launchd jobs.

The cron man page mentions -x options which enables "writing of debugging information to standard output." A side effect of this is that these also write basic information to standard error. Data sent to standard error is written to /var/log/system.log.

This results in data like this being written to /var/log/system.log:

debug flags enabled: misc
[42073] cron started
log_it: (user1 42084) CMD (/root/bin/mysql-backup)
log_it: (user1 42094) CMD (run-parts /etc/cron.hourly)

Since cron itself is launched by launchd, to enable this, I had to edit /System/Library/LaunchDaemons/com.vix.cron.plist so that it now looks like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.vix.cron</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/sbin/cron</string>
        <string>-x</string>
        <string>misc</string>
    </array>
    <key>KeepAlive</key>
    <dict>
        <key>PathState</key>
        <dict>
            <key>/etc/crontab</key>
            <true/>
        </dict>
    </dict>
    <key>QueueDirectories</key>
    <array>
        <string>/usr/lib/cron/tabs</string>
    </array>
    <key>EnableTransactions</key>
    <true/>
    <key>StandardErrorPath</key>
    <string>/var/log/cron.log</string>
</dict>
</plist>

I used -x misc here, but it didn't seem to matter which options I used. Adding the -x started the logging of job activity. I also added the StandardErrorPath to write to /var/log/cron.log instead of the default /var/log/system.log.

And then unload and reload this:

$ sudo launchctl
Password:
launchd% unload /System/Library/LaunchDaemons/com.vix.cron.plist 
launchd% load /System/Library/LaunchDaemons/com.vix.cron.plist 

Answer 2

Much easier to simply add the following to /etc/syslog.conf :

cron.*      /var/log/cron.log

Then restart syslog

sudo launchctl unload /System/Library/LaunchDaemons/com.apple.syslogd.plist
sudo launchctl load /System/Library/LaunchDaemons/com.apple.syslogd.plist

Tested and working on OSX 10.7.4

Answer 3

OSX now tends to use launchd rather than cron - Apple dev doc - so it might be there is nothing in cron to log.

Use launchctl to control the logging level of launchd. Som log info appears in system.log but more in the console app -> All messages

Answer 4

At least on Yosemite, cron logs output as mail messages, so use the mail to read them.