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

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       fuser — list process IDs of all processes that have one or  more  files
13       open
14

SYNOPSIS

16       fuser [-cfu] file...
17

DESCRIPTION

19       The  fuser  utility  shall  write to standard output the process IDs of
20       processes running on the local system that have one or more named files
21       open.   For block special devices, all processes using any file on that
22       device are listed.
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24       The fuser utility shall write to standard error additional  information
25       about the named files indicating how the file is being used.
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27       Any  output  for  processes running on remote systems that have a named
28       file open is unspecified.
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30       A user may need appropriate privileges to invoke the fuser utility.
31

OPTIONS

33       The fuser utility shall conform  to  the  Base  Definitions  volume  of
34       POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
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36       The following options shall be supported:
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38       -c        The  file  is  treated as a mount point and the utility shall
39                 report on any files open in the file system.
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41       -f        The report shall be only for the named files.
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43       -u        The user name, in parentheses, associated with  each  process
44                 ID  written  to  standard output shall be written to standard
45                 error.
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OPERANDS

48       The following operand shall be supported:
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50       file      A pathname on  which  the  file  or  file  system  is  to  be
51                 reported.
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STDIN

54       Not used.
55

INPUT FILES

57       The user database.
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ENVIRONMENT VARIABLES

60       The  following  environment  variables  shall  affect  the execution of
61       fuser:
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63       LANG      Provide a default value for  the  internationalization  vari‐
64                 ables  that are unset or null. (See the Base Definitions vol‐
65                 ume of POSIX.1‐2017, Section 8.2, Internationalization  Vari‐
66                 ables  for  the  precedence of internationalization variables
67                 used to determine the values of locale categories.)
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69       LC_ALL    If set to a non-empty string value, override  the  values  of
70                 all the other internationalization variables.
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72       LC_CTYPE  Determine  the  locale for the interpretation of sequences of
73                 bytes of text data as characters (for example, single-byte as
74                 opposed to multi-byte characters in arguments).
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76       LC_MESSAGES
77                 Determine the locale that should be used to affect the format
78                 and contents  of  diagnostic  messages  written  to  standard
79                 error.
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81       NLSPATH   Determine the location of message catalogs for the processing
82                 of LC_MESSAGES.
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ASYNCHRONOUS EVENTS

85       Default.
86

STDOUT

88       The fuser utility shall write the process ID  for  each  process  using
89       each  file given as an operand to standard output in the following for‐
90       mat:
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92
93           "%d", <process_id>
94

STDERR

96       The fuser utility shall write diagnostic messages to standard error.
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98       The fuser utility also shall write the following to standard error:
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100        *  The pathname of each named file is written followed immediately  by
101           a <colon>.
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103        *  For  each  process ID written to standard output, the character 'c'
104           shall be written to standard error if the process is using the file
105           as  its current directory and the character 'r' shall be written to
106           standard error if the process is using the file as its root  direc‐
107           tory.  Implementations  may  write  other  alphabetic characters to
108           indicate other uses of files.
109
110        *  When the -u option is specified, characters indicating the  use  of
111           the  file shall be followed immediately by the user name, in paren‐
112           theses, corresponding to the real user ID of the  process.  If  the
113           user  name cannot be resolved from the real user ID of the process,
114           the real user ID of the process shall be  written  instead  of  the
115           user name.
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117       When  standard output and standard error are directed to the same file,
118       the output shall be interleaved so that the  filename  appears  at  the
119       start  of each line, followed by the process ID and characters indicat‐
120       ing the use of the file. Then, if the -u option is specified, the  user
121       name or user ID for each process using that file shall be written.
122
123       A  <newline>  shall  be written to standard error after the last output
124       described above for each file operand.
125

OUTPUT FILES

127       None.
128

EXTENDED DESCRIPTION

130       None.
131

EXIT STATUS

133       The following exit values shall be returned:
134
135        0    Successful completion.
136
137       >0    An error occurred.
138

CONSEQUENCES OF ERRORS

140       Default.
141
142       The following sections are informative.
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APPLICATION USAGE

145       None.
146

EXAMPLES

148       The command:
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151           fuser -fu .
152
153       writes to standard output the process IDs of processes that  are  using
154       the current directory and writes to standard error an indication of how
155       those processes are using the directory and the user  names  associated
156       with the processes that are using the current directory.
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158
159           fuser -c <mount point>
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161       writes  to  standard output the process IDs of processes that are using
162       any file in the file system which  is  mounted  on  <mount  point>  and
163       writes to standard error an indication of how those processes are using
164       the files.
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166
167           fuser <mount point>
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169       writes to standard output the process IDs of processes that  are  using
170       the  file  which is named by <mount point> and writes to standard error
171       an indication of how those processes are using the file.
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173
174           fuser <block device>
175
176       writes to standard output the process IDs of processes that  are  using
177       any  file  which is on the device named by <block device> and writes to
178       standard error an indication of how those processes are using the file.
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180
181           fuser -f <block device>
182
183       writes to standard output the process IDs of processes that  are  using
184       the  file <block device> itself and writes to standard error an indica‐
185       tion of how those processes are using the file.
186

RATIONALE

188       The definition of the fuser utility follows existing practice.
189

FUTURE DIRECTIONS

191       None.
192

SEE ALSO

194       The Base Definitions volume of  POSIX.1‐2017,  Chapter  8,  Environment
195       Variables, Section 12.2, Utility Syntax Guidelines
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198       Portions  of  this text are reprinted and reproduced in electronic form
199       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
200       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
201       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
202       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
203       event of any discrepancy between this version and the original IEEE and
204       The  Open Group Standard, the original IEEE and The Open Group Standard
205       is the referee document. The original Standard can be  obtained  online
206       at http://www.opengroup.org/unix/online.html .
207
208       Any  typographical  or  formatting  errors that appear in this page are
209       most likely to have been introduced during the conversion of the source
210       files  to  man page format. To report such errors, see https://www.ker
211       nel.org/doc/man-pages/reporting_bugs.html .
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215IEEE/The Open Group                  2017                            FUSER(1P)
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