funmount(8)
NAME
funmount - forcibly unmount a file system
SYNOPSIS
funmount path
DESCRIPTION
- funmount forcibly attempts to unmount the file system
- mounted on path. It is roughly equivalent to running umount -f
- path. However, on most operating systems the umount command does
- a great deal more than simply execute the unmount system
- call--for instance it may attempt to read the attributes of the
- file system being unmounted and/or contact a remote NFS server to
- notify it of the unmount operation. These extra actions make
- umount hang when a remote NFS server is unavailable or a loopback
- server has crashed, which in turn causes the client to become ev
- er more wedged. funmount can avoid such situations when you are
- trying to salvage a machine with bad NFS mounts without rebooting
- it.
CAVEATS
- SFS will get very confused if you ever unmount file sys
- tems from beneath it. SFS's nfsmounter program tries to clean up
- the mess if the client software ever crashes. Running funmount
- will generally only make things worse by confusing nfsmounter.
SEE ALSO
- dirsearch(1), newaid(1), rex(1), sfsagent(1), sfskey(1),
- ssu(1), sfs_config(5), sfs_hosts(5), sfs_srp_params(5),
- sfs_users(5), sfsauthd_config(5), sfscd_config(5),
- sfsrosd_config(5), sfsrwsd_config(5), sfssd_config(5),
- sfs_environ(7), nfsmounter(8), sfsauthd(8), sfscd(8), sfsrosd(8),
- sfsrwcd(8), sfsrwsd(8), sfssd(8), vidb(8)
- The full documentation for SFS is maintained as a Texinfo
- manual. If the info and SFS programs are properly installed at
- your site, the command info SFS should give you access to the
- complete manual.
- For updates, documentation, and software distribution,
- please see the SFS website at http://www.fs.net/.
BUGS
- If /a is a mount point, and /a/b is another mount point,
- unmounting /a before /a/b will cause the latter file system to
- become ``lost.'' Once a file system is lost, there is no way to
- unmount it without rebooting. Worse yet, on some operating sys
- tems, commands such as df may hang because of a lost file system.
- Many operating systems will not let you unmount a file
- system (even forcibly) if a process is using the file system's
- root directory (for instance as a current working directory).
- Under such circumstances, funmount may fail. To unmount the file
- system you must find and kill whatever process is using the di
- rectory. Utilities such as fstat and lsof may be helpful for
- identifying processes with a particular file system open.
AUTHOR
- sfsdev@redlab.lcs.mit.edu
- SFS 0.8pre 2006-07-20