I was looking up stuff about cron and found nice. It is a way to run a program at a lower (or higher) priority than the rest of the things running on your box. I had noticed one of my old Mandrake installations ran a cron every night at 4 am and my desktop really took a performance hit, so this is something I needed. If you use the following command to build a program, it would run at a lower priority than other things on your machine:
nice +19 make
From man nice:
nice is built into csh(1)
with a slightly different syntax than described here. The form `nice +10' nices to positive nice, and
`nice -10' can be used by the superuser to give a process more of the processor.
So if I wanted to change my crons on my obsd box to run at low priority, I edit /var/cron/tabs/root:
# do daily/weekly/monthly maintainance 30 1 * * * root nice +19 /bin/csh /etc/daily 2>&1 | tee /var/log/daily.out | mail -s "`/bin/hostname` daily output" root 30 3 * * 6 root nice +19 /bin/csh /etc/weekly 2>&1 | tee /var/log/weekly.out | mail -s "`/bin/hostname` weekly output" root 30 5 1 * * root nice +19 /bin/csh /etc/monthly 2>&1 | tee /var/log/monthly.out | mail -s "`/bin/hostname` monthly output" root
I probably wouldn't really go as low as 19 because I run the distributed.net RC5 cracking client which is also low priority, so I would have to find a priority just above what it runs at for crons.