MKFIFO(3)						     Linux Programmer's Manual							 MKFIFO(3)

NAME

       mkfifo, mkfifoat - make a FIFO special file (a named pipe)

SYNOPSIS

       #include <sys/types.h>
       #include <sys/stat.h>

       int mkfifo(const char *pathname, mode_t mode);

       #include <fcntl.h>	    /* Definition of AT_* constants */
       #include <sys/stat.h>

       int mkfifoat(int dirfd, const char *pathname, mode_t mode);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mkfifoat():
	   Since glibc 2.10:
	       _POSIX_C_SOURCE >= 200809L
	   Before glibc 2.10:
	       _ATFILE_SOURCE

DESCRIPTION

       mkfifo()  makes	a  FIFO special file with name pathname.  mode specifies the FIFO's permissions.  It is modified by the process's umask in
       the usual way: the permissions of the created file are (mode & ~umask).

       A FIFO special file is similar to a pipe, except that it is created in a different way.	Instead of being an anonymous communications chan-
       nel, a FIFO special file is entered into the filesystem by calling mkfifo().

       Once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file.
       However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it.  Opening  a  FIFO
       for reading normally blocks until some other process opens the same FIFO for writing, and vice versa.  See fifo(7) for nonblocking handling
       of FIFO special files.

   mkfifoat()
       The mkfifoat() function operates in exactly the same way as mkfifo(), except for the differences described here.

       If the pathname given in pathname is relative, then it is interpreted relative to the directory referred to by the  file  descriptor  dirfd
       (rather than relative to the current working directory of the calling process, as is done by mkfifo() for a relative pathname).

       If  pathname is relative and dirfd is the special value AT_FDCWD, then pathname is interpreted relative to the current working directory of
       the calling process (like mkfifo()).

       If pathname is absolute, then dirfd is ignored.

RETURN VALUE

       On success mkfifo() and mkfifoat() return 0.  In the case of an error, -1 is returned (in which case, errno is set appropriately).

ERRORS

       EACCES One of the directories in pathname did not allow search (execute) permission.

       EDQUOT The user's quota of disk blocks or inodes on the filesystem has been exhausted.

       EEXIST pathname already exists.	This includes the case where pathname is a symbolic link, dangling or not.

       ENAMETOOLONG
	      Either the total length of pathname is greater than PATH_MAX, or	an  individual	filename  component  has  a  length  greater  than
	      NAME_MAX.   In  the  GNU	system, there is no imposed limit on overall filename length, but some filesystems may place limits on the
	      length of a component.

       ENOENT A directory component in pathname does not exist or is a dangling symbolic link.

       ENOSPC The directory or filesystem has no room for the new file.

       ENOTDIR
	      A component used as a directory in pathname is not, in fact, a directory.

       EROFS  pathname refers to a read-only filesystem.

       The following additional errors can occur for mkfifoat():

       EBADF  dirfd is not a valid file descriptor.

       ENOTDIR
	      pathname is a relative path and dirfd is a file descriptor referring to a file other than a directory.

VERSIONS

       mkfifoat() was added to glibc in version 2.4.  It is implemented using mknodat(2), available on Linux since kernel 2.6.16.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +---------------------+---------------+---------+
       |Interface	     | Attribute     | Value   |
       +---------------------+---------------+---------+
       |mkfifo(), mkfifoat() | Thread safety | MT-Safe |
       +---------------------+---------------+---------+
CONFORMING TO

       mkfifo(): POSIX.1-2001, POSIX.1-2008.

       mkfifoat(): POSIX.1-2008.

SEE ALSO

       mkfifo(1), close(2), open(2), read(2), stat(2), umask(2), write(2), fifo(7)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15								 MKFIFO(3)