.TH CRON 8 .SH NAME cron \- clock daemon .SH SYNOPSIS \fBcron\fR .br .de FL .TP \\fB\\$1\\fR \\$2 .. .de EX .TP 20 \\fB\\$1\\fR # \\$2 .. .SH EXAMPLES .EX "/usr/bin/cron" "Use absolute path in \fI/etc/rc\fR" .SH DESCRIPTION .PP \fICron\fR is clock daemon. It is typically started up by including the command \fI/usr/bin/cron\fR in the \fI/etc/rc\fR file. Once started, \fIcron\fR puts itself in the background, so no & is needed. It runs forever, sleeping most of the time. Once a minute it wakes up and examines \fI/usr/lib/crontab\fR to see if there is any work to do. If there is, the work is done. The entries of \fI/usr/lib/crontab\fR contain 6 elements each. Some examples follow: .PP .nf .ta 0.10i 0.40i 0.70i 1.0i 1.3i 1.8i 4.0i \fB Min Hr Dat Mo Day Command\fR \0* \0* \0* \0* \0* /usr/bin/date >/dev/log #print date every minute \00 \0* \0* \0* \0* /usr/bin/date >/dev/log #print date on the hour 30 \04 \0* \0* 1-5 /bin/backup /dev/fd1 #do backup Mon-Fri at 0430 30 19 \0* \0* 1,3,5 /etc/backup /dev/fd1 #Mon, Wed, Fri at 1930 \00 \09 25 12 \0* /usr/bin/sing >/dev/log #Xmas morning at 0900 only .fi .SH "SEE ALSO" .BR at (1).