A file system is specified either by giving the directory where it has been mounted, or by giving the special device on which it lives. The offending process could even be umount itself - it opens libc, and libc in its turn may open for example locale files.
Print help message and exit.
In case unmounting fails, try to remount read-only. More than one type may be specified in a comma separated list. The list of file system types can be prefixed with no to specify the file system types on which no action should be taken. This document was created by man2html , using the manual pages.