The cron daemon built into the NSLU2 doesn't perform any logging of jobs whatsoever, and by squashing the stdout and stderr streams means that some applications will not work as a cron job. An example of this is rsnapshot - the rsync portion will always fail with error 13 unless it is first directed through a script using this method.

A simple solution to this is create a simple batch file to capture the output of your applications and store them in the log directory.

1. telnet / ssh to your NSLU2.

2. Create a /opt/bin/cronlogger using your favourite editor add the following:

  #!/bin/sh

  # Work out names
  name=`basename $1`
  runthis="$1"

  # Update the log
  echo "`date` CRON: $*" >>/var/log/cronlog.log
  shift 1

  # Run the command
  "$runthis" >>"/var/log/$name.log" 2>&1 "$*" &

3. Change the permissions of the script to 755 like so:

  # chmod 755 /opt/bin/cronlogger

4. Edit /etc/crontab. The default lines look like this:

  0 0 * * root /usr/sbin/WatchDog? &>/dev/null

5. Change each line you want logging by adding a /opt/bin/cronlogger. e.g.

  0 0 * * root /opt/bin/cronlogger /usr/sbin/WatchDog? &>/dev/null

6. Save your changes and re-start cron:

  # /etc/rc.d/rc.crond

7. When a cron job you have modified starts new files will be automatically created in /var/log/. The <app name> is the "basename" of the job - so for our example of /usr/sbin/WatchDog? it will be WatchDog?

  cronlog.log         [contains what jobs have ran, when they ran]
  <app name>.log      [the output and error log from the application]

The behaviour above is easily modified by changing the script - for example you could break stdout and stderr into two files like so:

  "$runthis" >>"/var/log/$name.log" 2>>"/var/log/$name.stderr" "$*" &

Following version sends a copy by mail. It stores only output of the last run in the logfile.

  #!/bin/sh
  # email addresses
  sender="<sender@domain>"
  recipient="<recipient@domain>"

  # Get start time
  starttime=`date`

  # Work out names
  name=`basename $1`
  runthis="$1"

  # Update the log
  echo "`date` CRON: $*" >>/var/log/cronlog.log
  shift 1

  # Run the command
  "$runthis" >"/var/log/$name.log" 2>&1 "$*"

  # Send mail
  cat "/var/log/$name.log" | smtpclient -v --from=$sender --subject="Result of $name started at $starttime" $recipient