cron(8) [v7 man page]

CRON(8) 						      System Manager's Manual							   CRON(8)

NAME

       cron - clock daemon

SYNOPSIS

       /etc/cron

DESCRIPTION

       Cron executes commands at specified dates and times according to the instructions in the file /usr/lib/crontab.	Since cron never exits, it
       should only be executed once.  This is best done by running cron from the initialization process through the file /etc/rc; see init(8).

       Crontab consists of lines of six fields each.  The fields are separated by spaces or tabs.  The first five are integer patterns to  specify
       the  minute (0-59), hour (0-23), day of the month (1-31), month of the year (1-12), and day of the week (1-7 with 1=monday).  Each of these
       patterns may contain a number in the range above; two numbers separated by a minus meaning a range inclusive; a list of	numbers  separated
       by  commas  meaning any of the numbers; or an asterisk meaning all legal values.  The sixth field is a string that is executed by the Shell
       at the specified times.	A percent character in this field is translated to a new-line character.  Only the first line (up to a % or end of
       line) of the command field is executed by the Shell.  The other lines are made available to the command as standard input.

       Crontab is examined by cron every minute.

FILES

       /usr/lib/crontab

																	   CRON(8)

CRON(8) 						      System Manager's Manual							   CRON(8)

NAME

       cron - daemon to execute scheduled commands (Vixie Cron)

SYNOPSIS

       cron

DESCRIPTION

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

       Cron searches /var/spool/cron for crontab files which are named after accounts in /etc/passwd; crontabs found are loaded into memory.  Cron
       also searches for /etc/crontab and the files in the /etc/cron.d/ directory, which are in a different format (see  crontab(5)).	Cron  then
       wakes up every minute, examining all stored crontabs, checking each command to see if it should be run in the current minute.  When execut-
       ing 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 changed.	Thus cron need not be restarted whenever a crontab
       file is modified.  Note that the Crontab(1) command updates the modtime of the spool directory whenever it changes a crontab.

SEE ALSO

       crontab(1), crontab(5)

AUTHOR

       Paul Vixie <paul@vix.com>

4th Berkeley Distribution					 20 December 1993							   CRON(8)