For such a critical system component, why is cron so devilishly stupid? 1) Hour and minute are backwards. I get bitten by this all the time, particularly on days when I had to get up too early to do software patching on a few dozen servers. 2) For that matter, all the other time fields are backwards too. Must have been written by an American. In the rest of the sane world, we start with least significant and then work out way up to most significant (or the reverse). Not go backwards and forward all over the shop. 3) All the time fields are ANDed. Except day and month. So debian needs this hack to run mdadm check on first sunday of the month: 57 0 * * 0 root if [ -x /usr/share/mdadm/checkarray ] && [ $(date +\%d) -le 7 ]; then /usr/share/mdadm/checkarray --cron --all --idle --quiet; fi instead of this: 57 0 1-7 * 0 root if [ -x /usr/share/mdadm/checkarray ] ; then /usr/share/mdadm/checkarray --cron --all --idle --quiet; fi You have to go to extra effort to make it this bad. Why would you possibly want the date field to be ORed with the day of week? Was vixie on powerful drugs at the time? 4) "cron reads the crontab file(s) every minute to see whether there have been changes. Therefore, any change to its schedule will take effect within one minute." No, it reads the cron files every minute, and then applies the new schedule the next minute? Ie, there's always a minimum of a 1 minute delay to a schedule update, and up to 2 minutes. Why? Why would it not just read the new times, and if there's an entry for the current minute, act upon it instead of checking whether there was a job due the next minute to apply in the next minute? Again, this requires special kind of bodgery to get wrong. Unfortunately, this crappy behaviour is well embedded in the standard operation of cron, and can't be changed because it would break the expected broken behaviour. Can we define a new standard is-not-quite-cron? This rant brought to you by yet another "/tmp/crontab.uPh6Gi/crontab":24: bad hour errors in crontab file, can't install. Do you want to retry the same edit? (y/n)" -- Tim Connors