On Friday, March 7, 2003, at 03:16 AM, Allen Prunty worried:
> What does my mac do when I'm sleeping?
There's a utility called cron on Unix systems that is used to schedule
periodic tasks. The list of things your Mac does is contained in the
file /etc/crontab. Here's the one from Mac OS X
[Lee-Larsons-Computer:Mordor] lee% cat /etc/crontab
# /etc/crontab
SHELL=/bin/sh
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin
HOME=/var/log
#
#minute hour mday month wday who command
#
#*/5 * * * * root /usr/libexec/atrun
#
# Run daily/weekly/monthly jobs.
15 3 * * * root periodic daily
30 4 * * 6 root periodic weekly
30 5 1 * * root periodic monthly
A * in the chart is a wild card that means to do it all the times for
that column. It's a 24-hour clock. This one runs three different sets
of scripts that live in the directory /etc/periodic. You can look at
them with the terminal. They do things like rotate the log files and
remove temporary files. Sometimes they're even interesting to read
because of the technical language. For example, here's a snippet from
500.daily.
# Clean up NFS turds. May be useful on NFS servers.
#if [ "${host}" != "localhost" ]; then
# find / -name .nfs\* -mtime +7 -exec rm -f -- {} \; -o -fstype nfs
-prune
#fi
if [ -d /tmp ]; then
cd /tmp && {
find . -fstype local -type f -atime +3 -ctime +3 -exec rm -f -- {}
\;
find -fstype local -d . ! -name . -type d -mtime +1 -exec rmdir --
{} \; \
>/dev/null 2>&1; }
fi
| The next meeting of the Louisville Computer Society will
| be March 25. The LCS Web page is <http://www.kymac.org>.
