Provided by: psmisc_22.15-2ubuntu1_amd64 bug


       fuser - identify processes using files or sockets


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


       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 mode.

              r      root directory.

              m      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. 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 present:


       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 stderr.


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

       -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.

       -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 seatbelt 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/Ispace (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 access 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 namespaces.

       -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 namespaces.

       -      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 reasons.

       udp and tcp name spaces, and UNIX domain sockets can't be searched with kernels older than

       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.


       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.

       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

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


       Werner Almesberger <>

       Craig Small <>


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