23.10 Deletion with Prejudice: rm -f

The -f option to rm is the extreme opposite of -i (21.11). It says, "Just delete the file; don't ask me any questions." The "f" stands (allegedly) for "force," but this isn't quite right. rm -f won't force the deletion of something that you aren't allowed to delete. (To understand what you're allowed to delete, you need to understand file access permissions (22.2).)

What, then, does rm -f do, and why would you want to use it?

• Normally, rm asks you for confirmation if you tell it to delete files to which you don't have write access - you'll get a message like Override protection 444 for foo? (The UNIX filesystem allows you to delete read-only files, provided you own the file and provided you have write access to the directory.) With -f, these files will be deleted silently.

• Normally, rm's exit status (44.7) is 0 if it succeeded and 1 if it failed to delete the file. With -f, rm's return status is always 0.

I find that I rarely use rm -f on the UNIX command line, but I almost always use it within shell scripts. In a shell script, you (probably) don't want to be interrupted by lots of prompts should rm find a bunch of read-only files.

[You probably also don't want to be interrupted if rm -f tries to delete files that don't exist because the script never created them. In some UNIXes, rm -f will give an error here; in others, it won't. -JP]