If your system is operating close to capacity, you might be painfully aware of system resources. You might have to wait for programs to respond, take your place in long print queues, routinely clean out your home directory to conserve space, turn off fancy screen savers, or eschew reading certain newsgroups that your system no longer has the room to store.

If you have a smoothly running system with adequate resources—or if you work alone at night after everyone else has gone home—you might not even notice that you’re on a multiuser system. Response time to your commands might be nearly instantaneous, and you might not be aware of any upper limits on storage space. But don’t get smug about it, your time will come.

No matter how smoothly your system runs today, demands on most systems are increasing. New people get hired. Environments include more capabilities and user options. Programs and applications are updated to new versions that are smarter, more graphical, and more resource-intensive. More information is stored online. Computers are networked to remote machines.

Ten years ago, a standard company environment might have been a Wyse terminal with a single character display, running on a computer with a serial connection. Now, a standard environment in that same company might be a color X terminal with graphic applications like Mosaic and FrameMaker, running on a computer with full Internet access. Each of those “improvements” requires more system resources.

We continue to ask more of our computer systems, and we continue to run up against limits, of both disk space and system time. Chances are, at some time you’ll be asked to conserve disk space by removing extraneous files or to use less system time by stopping unnecessary processes.