23.19 Deleting (BSD) Manual Pages that Aren't Read

The BSD man (50.1) command comes with unformatted manual pages in directories named /usr/man/man... or /usr/share/man.... It also has empty directories for formatted manual pages named /usr/man/cat... or /usr/share/cat.... As people use man to read different pages, the man command puts each formatted manual page in these cat directories so they don't have to be formatted the next time they're read. [1]

[1] Newer BSD releases, Net.2 and 4.4BSD, use a new manual page scheme. Only the preformatted "cat" files are used. (The unformatted versions are kept with the source, so that they will be updated to match any changes in the source... or at least, to encourage this.)

The formatted manual pages can take a lot of disk space, though. You can keep preformatted copies of "high-demand" manual entries by removing those that prove not to be in high demand:

-atime	find /usr/man/cat? -atime +5 -exec rm -f {} \;