crontab.5

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH crontab 5
.SH Name
crontab \- clock daemon table file
.SH Syntax
.B /usr/lib/crontab
.SH Description
.NXR "crontab file"
.NXR "crontab file" "format"
.NXR "clock daemon" "crontab file"
The
.PN cron
command executes at specified dates and times
according to the instructions in the
.PN /usr/lib/crontab
file. The
.PN crontab
file consists of lines with six fields each.
The format for a line is as follows: 
.RS
.PP
.I minute hour day month weekday command
.RE
.PP
The following list defines each field in the line:
.IP "\fIminute\fP (0-59)" 15
The exact minute that the command sequence executes.
.IP "\fIhour\fP (0-23)"
The hour of the day that the command sequence executes. 
.IP "\fIday\fP (1-31)"
The day of the month that the command sequence executes.
.IP "\fImonth\fP (1-12)"
The month of the year that the command sequence executes.
.IP "\fIweekday\fP (1-7)"
The day of the week that the command sequence executes. Monday =
1, Tuesday = 2, and so forth.
.IP "\fIcommand\fP"
The complete command sequence variable that is to be executed.
Note that the command string must conform to Bourne shell syntax.
.PP The fields are separated by spaces or tabs.
The first five integer fields may be specified as follows:
.IP \(bu 4
A single number in the specified range
.IP \(bu 4
Two numbers separated by a minus,
meaning a range inclusive
.IP \(bu 4
A list of numbers separated by
commas, meaning any of the numbers
.IP \(bu 4
An asterisk meaning all legal values
.PP
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.
.SH Examples
The following example is part of a 
.PN crontab
file:
.EX
.nf
# 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 {} \\;
#

# redirecting error output
0 17 * * 1,3,5 /bin/tar \-cv /usr/sysads/smith > /dev/console 2>&1
#
.fi
.EE
.SH Files
.PN /etc/cron
.br
.PN /usr/lib/crontab
.SH See Also
sh(1), cron(8)
.br
.I Guide to System Environment Setup