NAME cron - daemon to execute scheduled commands (Vixie Cron)

SYNOPSIS cron

DESCRIPTION The cron program should be started from /etc/rc or /etc/rc.local. It will return immediately, so you don't need to start it with ``&''.

The cron program searches /var/cron/tabs for crontab files that are named after user accounts; these are loaded into memory. It also reads /etc/crontab, which is in a different format (see crontab(5)). The cron program then wakes up every minute, examining all stored crontabs, check- ing each command to see if it should be run in the current minute. When executing commands, any output is mailed to the owner of the crontab (or to the user named in the MAILTO environment variable in the crontab, if such exists).

Additionally, cron checks each minute to see if its spool directory's modtime (or the modtime on /etc/crontab) has changed, and if it has, cron will then examine the modtime on all crontabs and reload those which have will behave mysteriously if a system clock is reset backward by more than 59 seconds. Smaller steps, or steps forward, are handled correctly. changed. Thus cron need not be restarted whenever a crontab file is mod- ified. Note that the crontab(1) command updates the modtime of the spool directory whenever it changes a crontab.

DIAGNOSTICS Diagnostic messages are logged via syslog(3). Most describe temporary system resource allocation failures. If a file in /var/cron/tabs does not correspond to a valid user name, its name is logged as an ``orphan''.