FUSER(1)                   POSIX Programmer's Manual                  FUSER(1)



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

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

SYNOPSIS
       fuser [[-cfu]] file...

DESCRIPTION
       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.

OPTIONS
       The fuser utility shall conform to the Base Definitions volume of
       POSIX.1-2017, Section 12.2, Utility Syntax Guidelines.

       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.

OPERANDS
       The following operand shall be supported:

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

STDIN
       Not used.

INPUT FILES
       The user database.

ENVIRONMENT VARIABLES
       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, Section 8.2, Internationalization
                 Variables 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.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       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>

STDERR
       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.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       None.

EXAMPLES
       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 <mount point>

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


           fuser <mount point>

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


           fuser <block device>

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


           fuser -f <block device>

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

RATIONALE
       The definition of the fuser utility follows existing practice.

FUTURE DIRECTIONS
       None.

SEE ALSO
       The Base Definitions volume of POSIX.1-2017, Chapter _8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT
       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(1)
