Many of the techniques in this chapter aren't nearly as applicable as they once were. At the time of this writing, EIDE disks are about a dollar a gigabyte; even fast-wide SCSI isn't that expensive. Often the solution to running low on disk space is just to buy more.
That said, many of these techniques illustrate useful things to know about Unix. It's common these days to run Unix on an old, spare machine where it's not worth the trouble of upgrading the disks. You may also be dealing with a Unix box at work or school that uses expensive, highly reliable disks with expensive backup procedures in place, where more disk space just isn't an option. It never hurts to know how to eke the last few bytes out of a partition.
This chapter also has a lot of information about compressing and decompressing files, which is fairly common. (These days, you may well compress files to save network bandwidth rather than disk space, but the same principles apply.) So enjoy exploring!
Sometimes you don't want to remove a file completely — you just want to empty it:
If an active process has the file open (not uncommon for log files), removing the file and creating a new one will not affect the logging program; those messages will just keep going to the file that's no longer linked. Emptying the file doesn't break the association, and so it clears the file without affecting the logging program.
When you remove ...