fuser(1) — Linux manual page


FUSER(1)                        User Commands                       FUSER(1)

NAME         top

       fuser - identify processes using files or sockets

SYNOPSIS         top

       fuser [-fuv] [-a|-s] [-4|-6] [-c|-m|-n space] [ -k [-i] [-M] [-w]
       [-SIGNAL] ] name ...
       fuser -l
       fuser -V

DESCRIPTION         top

       fuser 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:

              c      current directory.
              e      executable being run.
              f      open file.  f is omitted in default display mode.
              F      open file for writing.  F is omitted in default display
              r      root directory.
              m      mmap'ed file or shared library.
              .      Placeholder, omitted in default display mode.

       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. By
       default fuser will look in both IPv6 and IPv4 sockets.  To change the
       default, behavior, use the -4 and -6 options.  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


       Either symbolic or numeric values can be used for IP addresses and
       port numbers.

       fuser outputs only the PIDs to stdout, everything else is sent to

OPTIONS         top

       -a, --all
              Show all files specified on the command line.  By default,
              only files that are accessed by at least one process are

       -c     Same as -m option, used for POSIX compatibility.

       -f     Silently ignored, used for POSIX compatibility.

       -k, --kill
              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.

       -i, --interactive
              Ask the user for confirmation before killing a process.  This
              option is silently ignored if -k is not present too.

       -I, --inode
              For the name space file let all comparisons be based on the
              inodes of the specified file(s) and never on the file names
              even on network based file systems.

       -l, --list-signals
              List all known signal names.

       -m NAME , --mount NAME
              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 directory.

       -M, --ismountpoint
              Request will be fulfilled only if NAME specifies a mountpoint.
              This is an invaluable seat belt which prevents you from
              killing the machine if NAME happens to not be a filesystem.

       -w     Kill only processes which have write access.  This option is
              silently ignored if -k is not present too.

       -n SPACE, --namespace 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., 80/tcp) can be used.

       -s, --silent
              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 (e.g., -1).  This option is silently
              ignored if the -k option is not used.

       -u, --user
              Append the user name of the process owner to each PID.

       -v, --verbose

              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.  Verbose mode will also
              show when a particular file is being accessed as a mount
              point, knfs export or swap file.  In this case kernel is shown
              instead of the PID.

       -V, --version
              Display version information.

       -4, --ipv4
              Search only for IPv4 sockets.  This option must not be used
              with the -6 option and only has an effect with the tcp and udp

       -6, --ipv6
              Search only for IPv6 sockets.  This option must not be used
              with the -4 option and only has an effect with the tcp and udp

       -      Reset all options and set the signal back to SIGKILL.

FILES         top

       /proc  location of the proc file system

EXAMPLES         top

       fuser -km /home
              kills all processes accessing the file system /home in any

       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.

RESTRICTIONS         top

       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.

       fuser cannot report on any processes that it doesn't have permission
       to look at the file descriptor table for.  The most common time this
       problem occurs is when looking for TCP or UDP sockets when running
       fuser as a non-root user.  In this case fuser will report no access.

       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.

       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.

BUGS         top

       fuser -m /dev/sgX will show (or kill with the -k flag) all processes,
       even if you don't have that device configured.  There may be other
       devices it does this for too.

       The mount -m option will match any file within the same device as the
       specified file, use the -M option as well if you mean to specify only
       the mount point.

SEE ALSO         top

       kill(1), killall(1), lsof(8), pkill(1), ps(1), kill(2).

COLOPHON         top

       This page is part of the psmisc (Small utilities that use the /proc
       filesystem) project.  Information about the project can be found at
       ⟨https://gitlab.com/psmisc/psmisc⟩.  If you have a bug report for
       this manual page, see ⟨https://gitlab.com/psmisc/psmisc/issues⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://gitlab.com/psmisc/psmisc.git⟩ on 2020-07-14.  (At that time,
       the date of the most recent commit that was found in the repository
       was 2020-05-22.)  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-to-
       date source for the page, or you have corrections or improvements to
       the information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

psmisc                           2016-04-04                         FUSER(1)

Pages that refer to this page: killall(1)lsof(8)