# mkfifo

## 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.
    


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