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
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
A user may need appropriate privilege to invoke the fuser utility.
The following environment variables shall affect the execution of fuser:
Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, Internationalization
Variables for the precedence of internationalization variables used to
determine the values of locale categories.)
If set to a non-empty string value, override the values of
all the other internationalization variables.
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).
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to standard error.
Determine the location of message catalogs for the
processing of LC_MESSAGES.
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 process' real user ID. If the
user name cannot be resolved from the process' real user ID, the process'
real user ID 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.
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.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 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