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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:
               _XOPEN_SOURCE >= 700 || _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 permis‐
       sions.  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 channel, 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  writ‐
       ing, 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 dif‐
       ferences 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  inter‐
       preted 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), avail‐
       able on Linux since kernel 2.6.16.

ATTRIBUTES
   Multithreading (see pthreads(7))
       The mkfifo() and mkfifoat() functions are thread-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 3.74 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 http://www.kernel.org/doc/man-pages/.



GNU                                         2014-03-24                                  MKFIFO(3)


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