mkfifo(3) — Linux manual page


mkfifo(3)               Library Functions Manual               mkfifo(3)

NAME         top

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

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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

           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:

DESCRIPTION         top

       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 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 writing, and
       vice versa.  See fifo(7) for nonblocking handling of FIFO special

       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.

       See openat(2) for an explanation of the need for mkfifoat().

RETURN VALUE         top

       On success mkfifo() and mkfifoat() return 0.  On error, -1 is
       returned and errno is set to indicate the error.

ERRORS         top

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

       EBADF  (mkfifoat()) pathname is relative but dirfd is neither
              AT_FDCWD nor a valid file descriptor.

       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.

              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.

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

              (mkfifoat()) pathname is a relative pathname and dirfd is
              a file descriptor referring to a file other than a

       EROFS  pathname refers to a read-only filesystem.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface                           Attribute     Value   │
       │ mkfifo(), mkfifoat()                │ Thread safety │ MT-Safe │

VERSIONS         top

       It is implemented using mknodat(2).

STANDARDS         top


HISTORY         top


              glibc 2.4.  POSIX.1-2008.

SEE ALSO         top

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

COLOPHON         top

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Linux man-pages 6.9.1          2024-05-02                      mkfifo(3)

Pages that refer to this page: mkfifo(1)mknod(2)open(2)umask(2)unlink(2)remove(3)fifo(7)pipe(7)signal-safety(7)