fuser



FUSER(1)                         User Commands                        FUSER(1)




NAME

       fuser - identify processes using files or sockets


SYNOPSIS

       fuser [-a|-s|-c] [-4|-6] [-n space] [-k [-i] [-signal] ] [-muvf] name
       ...
       fuser -l
       fuser -V


DESCRIPTION

       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.

              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  corre-
       sponding  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,
       behavour,  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:

       [lcl_port][,[rmt_host][,[rmt_port]]]

       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.


OPTIONS

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

       -l     List all known signal names.

       -m     name specifies a file on a mounted file system or a block device
              that is mounted. All processes accessing files on that file sys-
              tem  are  listed.  If a directory file is specified, it is auto-
              matically changed to name/. to use any file system that might be
              mounted on that directory.

       -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 sym-
              bolic name can be specified.  If  there  is  no  ambiguity,  the
              shortcut notation name/space (e.g. name/proto) can be used.

       -s     Silent  operation.  -u and -v are ignored in this mode.  -a must
              not be used with -s.

       -signal
              Use the specified signal instead of SIGKILL  when  killing  pro-
              cesses.  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     Append the user name of the process owner to each PID.

       -v     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.

       -V     Display version information.

       -4     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 names-
              paces.

       -6     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 names-
              paces.

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


FILES

       /proc     location of the proc file system


EXAMPLES

       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.


RESTRICTIONS

       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 1.3.78.

       udp and tcp currently  work with IPv6 and IPv4, but the address  fields
       can only be IPv4 addresses.

       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

       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.


AUTHORS

       Werner Almesberger <werner@almesberger.net>

       Craig Small <csmall@small.dropbear.id.au>


SEE ALSO

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



Linux                         September 26, 2003                      FUSER(1)

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