This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Default.

       Default.

       Thefollowingsectionsareinformative.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                         FUSER(1POSIX)

       The fuser utility shall write to standard output the process IDs of processes running on the local system
       that  have one or more named files open.  For block special devices, all processes using any file on that
       device are listed.

       The fuser utility shall write to standard error additional information about the named  files  indicating
       how the file is being used.

       Any output for processes running on remote systems that have a named file open is unspecified.

       A user may need appropriate privileges to invoke the fuser utility.

       The following environment variables shall affect the execution of fuser:

       LANG      Provide a default value for the internationalization variables that are unset or null. (See the
                 Base Definitions volume of POSIX.1‐2017, Section8.2, InternationalizationVariables  for  the
                 precedence   of   internationalization  variables  used  to  determine  the  values  of  locale
                 categories.)

       LC_ALL    If set to a non-empty string value, override the values of all the  other  internationalization
                 variables.

       LC_CTYPE  Determine  the  locale  for the interpretation of sequences of bytes of text data as characters
                 (for example, single-byte as opposed to multi-byte characters in arguments).

       LC_MESSAGES
                 Determine the locale that should be used to  affect  the  format  and  contents  of  diagnostic
                 messages written to standard error.

       NLSPATH   Determine the location of message catalogs for the processing of LC_MESSAGES.

       The command:

           fuser -fu .

       writes to standard output the process IDs of processes that are using the current directory and writes to
       standard error an indication of how those processes are using the directory and the user names associated
       with the processes that are using the current directory.

           fuser -c <mountpoint>

       writes  to  standard output the process IDs of processes that are using any file in the file system which
       is mounted on <mountpoint> and writes to standard error an indication of how those processes  are  using
       the files.

           fuser <mountpoint>

       writes  to  standard output the process IDs of processes that are using the file which is named by <mountpoint> and writes to standard error an indication of how those processes are using the file.

           fuser <blockdevice>

       writes to standard output the process IDs of processes that are using any file which  is  on  the  device
       named  by  <blockdevice> and writes to standard error an indication of how those processes are using the
       file.

           fuser -f <blockdevice>

       writes to standard output the process IDs of processes that are using the file <blockdevice> itself  and
       writes to standard error an indication of how those processes are using the file.

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

       None.

       None.

       The user database.

       fuser — list process IDs of all processes that have one or more files open

       The following operand shall be supported:

       file      A pathname on which the file or file system is to be reported.

       The  fuser  utility  shall  conform to the Base Definitions volume of POSIX.1‐2017, Section12.2, UtilitySyntaxGuidelines.

       The following options shall be supported:

       -c        The file is treated as a mount point and the utility shall report on any files open in the file
                 system.

       -f        The report shall be only for the named files.

       -u        The user name, in parentheses, associated with each process ID written to standard output shall
                 be written to standard error.

       None.

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       The definition of the fuser utility follows existing practice.

       The  Base  Definitions  volume  of  POSIX.1‐2017, Chapter8, EnvironmentVariables, Section12.2, UtilitySyntaxGuidelines

       The fuser utility shall write diagnostic messages to standard error.

       The fuser utility also shall write the following to standard error:

        *  The pathname of each named file is written followed immediately by a <colon>.

        *  For each process ID written to standard output, the character 'c' shall be written to standard  error
           if  the  process is using the file as its current directory and the character 'r' shall be written to
           standard error if the process is using the file as its  root  directory.  Implementations  may  write
           other alphabetic characters to indicate other uses of files.

        *  When  the  -u  option  is  specified,  characters  indicating  the  use of the file shall be followed
           immediately by the user name, in parentheses, corresponding to the real user ID of  the  process.  If
           the  user  name  cannot  be  resolved  from  the real user ID of the process, the real user ID of the
           process shall be written instead of the user name.

       When standard output and standard error are directed to the same file, the output shall be interleaved so
       that the filename appears at the start of each line, followed by the process ID and characters indicating
       the use of the file. Then, if the -u option is specified, the user name or user ID for each process using
       that file shall be written.

       A <newline> shall be written to standard error after the  last  output  described  above  for  each  file
       operand.

       Not used.

       The  fuser  utility  shall  write  the process ID for each process using each file given as an operand to
       standard output in the following format:

           "%d", <process_id>

       fuser [-cfu]file...