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 .

       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 .