So, since most Unix computers were left running 24/7, they took advantage of Unix's cron automation utility to schedule the execution of these scripts at times when computers would least likely be in use. Because Unix computers have historically been used as servers or number-crunching workstations, system administrators didn't want to run these scripts-which can take a good deal of time and system resources-during the day when users were most likely to be using the computer. Unfortunately, on many Macs these scripts never get run. They run, as you might guess, daily, weekly, and monthly, respectively.

These scripts remove unnecessary temporary files, archive or delete old log files, and update databases (such as the locate database I talked about in Chapter 5). To take care of these tasks, Unix computers (including yours, running OS X) use three scripts, called daily, weekly, and monthly, to perform these actions. Unix operating systems maintain a number of activity logs (discussed later in the chapter), databases, and temporary files that need to be cleaned out and/or updated periodically.

One of these is its reliance on 'cleanup' scripts. Because OS X is based on Unix, it still exhibits a few remnants of classic Unix behavior.

System maintenance for mac