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I've got a bunch of linux servers, hosted on Amazon Web Services. Most are Amazon Linux, but two are RHEL 5. On all servers, in my /etc/cron.d directory, I have a cron file that invokes a custom Java tool to back up the virtual hard disks. All servers' cron scripts are supposed to run at midnight.
Looking at the timestamps on the virtual hard disk backups, I can see the Amazon Linux ones are indeed created at midnight UTC. However, the RHEL 5 ones are late. Today's backup is exactly 4 hours late, for both RHEL 5 servers. Yesterday it was 4:47 late, again for both servers. So cron is definitely getting invoked, and the backups are getting carried out, but not when I scheduled them.
On my RHEL 5 server, /var/log/cron does indeed have entries timestamped midnight. If I do "date -u" it shows the same time as the Amazon Linux servers.
Command "date -u" will show you time in UTC i.e. Universal time, whereas command "date" will show you time according to timezone configured in the server. However, as far as I am concered, cron will run according to time shown in "date" command, not according to "date -u" command.
~$ date -u
So either modify your cron entry according to output of "date" command or modify server's timezone.