MKFIFO
Section: POSIX Programmer's Manual (1P)
Updated: 2017
Page Index
PROLOG
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.
NAME
mkfifo
--- make FIFO special files
SYNOPSIS
mkfifo [-m mode] file...
DESCRIPTION
The
mkfifo
utility shall create the FIFO special files specified by the operands,
in the order specified.
For each
file
operand, the
mkfifo
utility shall perform actions equivalent to the
mkfifo()
function defined in the System Interfaces volume of POSIX.1-2017, called with the following arguments:
- 1.
-
The
file
operand is used as the
path
argument.
- 2.
-
The value of the bitwise-inclusive OR of S_IRUSR, S_IWUSR, S_IRGRP,
S_IWGRP, S_IROTH, and S_IWOTH is used as the
mode
argument. (If the
-m
option is specified, the value of the
mkfifo()
mode
argument is unspecified, but the FIFO shall at no time have permissions
less restrictive than the
-m
mode
option-argument.)
OPTIONS
The
mkfifo
utility shall conform to the Base Definitions volume of POSIX.1-2017,
Section 12.2,
Utility Syntax Guidelines.
The following option shall be supported:
- -m mode
-
Set the file permission bits of the newly-created FIFO to the specified
mode
value. The
mode
option-argument shall be the same as the
mode
operand defined for the
chmod
utility. In the
symbolic_mode
strings, the
op
characters
'+'
and
'-'
shall be interpreted relative to an assumed initial mode of
a=rw.
OPERANDS
The following operand shall be supported:
- file
-
A pathname of the FIFO special file to be created.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of
mkfifo:
- 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
Not used.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
- 0
-
All the specified FIFO special files were created successfully.
- >0
-
An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
None.
EXAMPLES
None.
RATIONALE
This utility was added to permit shell applications to create FIFO
special files.
The
-m
option was added to control the file mode, for consistency with the
similar functionality provided by the
mkdir
utility.
Early proposals included a
-p
option similar to the
mkdir
-p
option that created intermediate directories leading up to the FIFO
specified by the final component. This was removed because it is not
commonly needed and is not common practice with similar utilities.
The functionality of
mkfifo
is described substantially through a reference to the
mkfifo()
function in the System Interfaces volume of POSIX.1-2017. For example, by default, the mode of the FIFO
file is affected by the file mode creation mask in accordance with the
specified behavior of the
mkfifo()
function. In this way, there is less duplication of effort required for
describing details of the file creation.
FUTURE DIRECTIONS
None.
SEE ALSO
chmod,
umask
The Base Definitions volume of POSIX.1-2017,
Chapter 8, Environment Variables,
Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1-2017,
mkfifo()
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 .
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