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 IEEE Std 1003.1-2001,
called with the following arguments:
The file operand is used as the path argument.
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 -mmode
option-argument.)
OPTIONS
The mkfifo utility shall conform to the Base Definitions volume
of IEEE Std 1003.1-2001, 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
IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001. 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 System Interfaces volume of
IEEE Std 1003.1-2001, mkfifo()
COPYRIGHT
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 .
