MacOS – Where does SFTPD log to

While I suspect that this is not what you want to do, you could always do something like schedule a maintenance task to run to limit the size of the file.

Something like this in a shell script that you schedule:

tail -n 10000 /var/log/DiagnosticMessages > /var/log/DiagnosticMessages

Or if you want to keep a history of the contents, something like this:

mv /var/log/DiagnosticMessages /var/log/DiagnosticMessages_$(date +%y%m%d)

If you want to get fancy, you could:

cat /var/log/DiagnosticMessages | wc -l

and then only rename the file if > 10K. As usual it all depends on how much effort you want to put into it, and whether or not you want a history of this file.

And as you said....this doesn't actually resolve the root cause.

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.)