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