# fuser

## 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 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** _NAMESPACE_ , **--namespace** _NAMESPACE_
                  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.
    


## 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** _command_**; fi**
                  invokes _command_ 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.
    
           **fuser** will not see block devices mounted by processes in a
           different mount namespace.  This is due to the device ID shown in
           the process' file descriptor table being from the process
           namespace, not fuser's; meaning it won't match.
    


## 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.
    
           **fuser** will not match mapped files, such as a process' shared
           libraries if they are on a **btrfs**(5) filesystem due to the device
           IDs being different for stat(2) and _/proc/ <PID>/maps_.
    


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