Mac Forum / General / General / May 2008

Ok.  Try this:

1. Open a terminal window.

2. Enter this command:

    crontab -e

Cron will start the default command-line editor (usually vi - and I will
assume it's vi in these instructions) to edit your cron table.

3. Use the arrow keys on the keyboard to move the cursor to the very
last line in the table.

4. Press the i key on the keyboard to enter (i)nsert mode.

5. If you are not on a blank line, press the right arrow key on the
keyboard to move all the way to the end of the line, then press the
Return key on the keyboard to create a blank line at the very end of the
table.

6. Type this line and press the Return key:

    /5 * * * * date >> /Users/you/Desktop/crontest.log 2>&1

7. Press the Escape key on the keyboard to exit (I)nsert mode.

8. Type a colon (:) character to enter command mode, followed
immediately by a w character to indicate you want to (w)rite), followed
immediately by a q character (to indicate you want to (q)uit):

    :wq

9. Press Return to execute the command.

You should see a message like this:

    crontab: installing new crontab

If you see a message indicating there is a syntax error, you've got a
typo and you should answer yes (y) to the "Do you want to retry the same
edit?" prompt, then correct the typo by entering (i)nsert mode again,
moving to the problem line, and correcting the typo. Then do the :wq
command again.

The /5 * * * * date >> /Users/dlache/Desktop/crontest.log 2>&1 line
tells cron to execute the 'date' command every 5th minute of every hour
of every day, and send the output of the command, along with errors (if
any) to the file /Users/you/Desktop/crontest.log.

Now just sit back and wait for the next 5-minute increment (5, 10, 15,
20, and so on). If cron is executing your cron table, a crontest.log
file should appear on the desktop, and it should contain the output of
the 'date' command at the time of each execution.

The two crontab entries above were placed there by SuperDuper! itself as a
byproduct of using SuperDuper!'s scheduling facility.

The issue is that although the vast majority of time the scheduled backups do
indeed run there have been a couple of times when they did not run. it has
been suggested to me that in the cases where the scheduled backups did not
occur the issue might be that cron itself did not run.

The 'open' command-line tool understands URLs. See the manual for
details.

[continuing in the "is cron running" saga]

Is there a simple terminal command that I can enter to view the above
mentioned log?

No, that happens only on Leopard, and it's a bug. Some have reported
clean installing Leopard fixes the issue, but I haven't read any real
diagnosis of what actually causes the message.

At any rate, it's not like users of SuperDuper have a choice. SuperDuper
currently uses cron to schedule backups, and that's what we're stuck
with. And the messages aren't going to hurt anything anyway.