crontab(5)

Name

crontab − clock daemon table file

Syntax

/usr/lib/crontab

Description

The cron command executes at specified dates and times according to the instructions in the /usr/lib/crontab file. The crontab file consists of lines with six fields each. The format for a line is as follows:

minute hour day month weekday command

The following list defines each field in the line:

minute (0-59)The exact minute that the command sequence executes.

hour (0-23)The hour of the day that the command sequence executes.

day (1-31)The day of the month that the command sequence executes.

month (1-12)The month of the year that the command sequence executes.

weekday (1-7)The day of the week that the command sequence executes. Monday = 1, Tuesday = 2, and so forth.

commandThe complete command sequence variable that is to be executed.

The first five integer fields may be specified as follows:

•A single number in the specified range

•Two numbers separated by a minus, meaning a range inclusive

•A list of numbers separated by commas, meaning any of the numbers

•An asterisk meaning all legal values

The sixth field is a string that is executed by the shell at the specified times. A percent sign (%) in this field is translated to a new-line character. Only the first line of the command field, up to a percent sign (%) or end of line, is executed by the shell. The other lines are made available to the command as standard input.

Examples

The following example is part of a crontab file:

# periodic things
0,15,30,45 * * * * (echo ’^M’ ‘date‘; echo ’ ’) >/dev/console
0,15,30,45 * * * * /usr/lib/atrun
# daily stuff
5 4 * * * sh /usr/adm/newsyslog
15 4 * * * ( cd /usr/preserve; find . -mtime +7 -a -exec rm -f {} ; )
20 4 * * * find /usr/msgs -mtime +21 -a ! -perm 444 -a ! -name bounds
-a -exec rm -f {} ;
# NOTE: The above line is wrapped.
# local cleanups
30 4 * * * find /usr/spool/mqueue -type f -mtime +5 -name df-exec rm {} ;
35 4 * * * find /usr/spool/mqueue -type f -mtime +5 -name tf-exec rm {} ;
40 4 * * * find /usr/spool/rwho -type f -mtime +21 -exec rm {} ;
#

Files

/etc/cron
/usr/lib/crontab

Museum