focal (1) fuser.1.gz

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NAME

       fuser - identify processes using files or sockets

SYNOPSIS

       fuser [-fuv] [-a|-s] [-4|-6] [-c|-m|-n space] [ -k [-i] [-M] [-w] [-SIGNAL] ] 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.
              F      open file for writing.  F is omitted in default display mode.
              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 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, --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.

       -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.

       -SIGNAL
              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 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.

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.

       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 reasons.

       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

       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

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