Where is the cron log file in MacOSX Lion?
I want to troubleshoot a cron job that worked fine until a recent modification, but I can't find the cron log file, where is it?
By default, cron does not log output of executed jobs. It is possible to log the fact that cronjobs have been executed, but that is not the default on OS X either.
In order to investigate cronjob execution output, I suggest modifying your cronjob line to redirect STDOUT and STDERR to logfiles. In your crontab file or after running crontab -e, however you go about it, add something like the following to your job line:
0 0 * * * yourcommand >/tmp/stdout.log 2>/tmp/stderr.log
Doing this should send STDOUT (normally printed or echo'ed output to STDOUT) to a text file named stdout.log in the /tmp directory, and STDERR to stderr.log in the temp directory. Many utilities use STDERR to print special error messages out when they're application errors, and not errors generated by the program's actual execution. (You can read more about STDERR on Wikipedia.)
By default, "logging" is not enabled. But you may get some useful information by running the mail command.
TL;DR on the mail command: press enter to read messages, and then q and enter to quit.
Much easier to simply add the following to /etc/syslog.conf :
cron.* /var/log/cron.log
Then tell syslog to reload its configuration:
sudo launchctl kill SIGHUP system/com.apple.syslogd.plist
or to add the following in /etc/asl/com.vix.cron (which makes the log file discoverable for log consumers like the Console.app):
# Cron logging output, from the /System/Library/LaunchDaemons/com.vix.cron.plist launch daemon
> cron.log mode=0640 format=bsd rotate=seq compress file_max=5M all_max=50M
? [= Facility cron] [<= Level info] file cron.log
Tested and working on macOS 11.3
I was able to find cron-job log in,
/var/mail/{user-name}
Following is a cron job log I got for running an AWS CLI command,
From [email protected] Fri Mar 2 10:00:00 2018
Return-Path: <[email protected]>
X-Original-To: build
Delivered-To: [email protected]
Received: by BuildServer1.local (Postfix, from userid 501)
id A7A94296CBA3; Fri, 2 Mar 2018 10:00:00 +0100 (CET)
From: [email protected] (Cron Daemon)
To: [email protected]
Subject: Cron <build@BuildServer1> /app/scripts/s3-sync.sh
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=build>
X-Cron-Env: <USER=build>
X-Cron-Env: <HOME=/Users/build>
Message-Id: <[email protected]>
Date: Fri, 2 Mar 2018 10:00:00 +0100 (CET)
upload: ../../app/logs/debug.log to s3://**my-s3***/app/logs/debug.log
Turned out when cron is running the job (as me), /usr/local/bin is not in the PATH.
I found this by trial and error and building the job from scratch from a simple things that I knew would work and gradually added things until I found the problem.
About the other suggestions and answers:
For some reason (at least on my machine, which is running a Lion upgraded from SnowLeopard) cron does not use the parameters specified in the plist files that launchd is sopposed to read /System/Library/LaunchDaemons/com.vix.cron.plist or maybe cron on Lion does not write anything to stdout or stderr.
By the way I am using http://s3tools.org/s3cmd to sync a folder with an Amazon S3 bucket as a backup (like a primitive DropBox).