Section: User Commands (1)
Updated: October 25, 1999Index
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fuser - identify processes using files or sockets
displays the PIDs of processes using the specified files or file systems.
In the default display mode, each file name is followed by a letter denoting
the type of access:
executable being run.
open file. f is omitted in default display mode.
mmap'ed file or shared library.
fuser returns a non-zero return code if none of the specified files
is accessed or in case of a fatal error. If at least one access has been
found, fuser returns zero.
In order to look up processes using TCP and UDP sockets, the corresponding
name space has to be selected with the -n option. Then the socket(s) can
be specified by the local and remote port, and the remote address. All fields
are optional, but commas in front of missing fields must be present:
Either symbolic or numeric values can be used for IP addresses and port
Show all files specified on the command line. By default, only files that are
accessed by at least one process are shown.
Kill processes accessing the file. Unless changed with -signal,
SIGKILL is sent. An fuser process never kills itself, but may kill
other fuser processes. The effective user ID of the process executing
fuser is set to its real user ID before attempting to kill.
Ask the user for confirmation before killing a process. This option is
silently ignored if -k is not present too.
List all known signal names.
name specifies a file on a mounted file system or a block device that
is mounted. All processes accessing files on that file system are listed.
If a directory file is specified, it is automatically changed to
name/. to use any file system that might be mounted on that
- -n space
Select a different name space. The name spaces file (file names, the
default), udp (local UDP ports), and tcp (local TCP ports) are
supported. For ports, either the port number or the symbolic name can be
specified. If there is no ambiguity, the shortcut notation
name/space (e.g. name/proto) can be used.
Silent operation. -u and -v are ignored in this mode.
-a must not be used with -s.
Use the specified signal instead of SIGKILL when killing processes. Signals
can be specified either by name (e.g. -HUP) or by number
Append the user name of the process owner to each PID.
Verbose mode. Processes are shown in a ps-like style. The fields PID,
USER and COMMAND are similar to ps. ACCESS shows how the process
accesses the file. If the access is by the kernel (e.g. in the case of a
mount point, a swap file, etc.), kernel is shown instead of the PID.
Display version information.
Reset all options and set the signal back to SIGKILL.
/proc location of the proc file system
fuser -km /home
kills all processes accessing the file system /home
in any way.
if fuser -s /dev/ttyS1; then :; else something; fi invokes
something if no other process is using /dev/ttyS1.
fuser telnet/tcp shows all processes at the (local) TELNET port.
Processes accessing the same file or file system several times in the same way
are only shown once.
If the same object is specified several times on the command line, some of
those entries may be ignored.
fuser may only be able to gather partial information unless run with
privileges. As a consequence, files opened by processes belonging to other
users may not be listed and executables may be classified as mapped only.
Installing fuser SUID root will avoid problems associated with
partial information, but may be undesirable for security and privacy
udp and tcp name spaces, and UNIX domain sockets can't be
searched with kernels older than 1.3.78.
udp and tcp currently only work for IPv4.
Accesses by the kernel are only shown with the -v option.
The -k option only works on processes. If the user is the kernel,
fuser will print an advice, but take no action beyond that.
Werner Almesberger <Werner.Almesberger@epfl.ch
- SEE ALSO