NAME

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

LIBRARY

       Standard C library (libc, -lc)

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 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 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.

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

RETURN VALUE

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

ERRORS

       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.

       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.

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

       EROFS  pathname refers to a read-only filesystem.

ATTRIBUTES

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

       ┌──────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                     │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │mkfifo(), mkfifoat()                                                          │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

VERSIONS

       It is implemented using mknodat(2).

STANDARDS

       POSIX.1-2008.

HISTORY

       mkfifo()
              POSIX.1-2001.

       mkfifoat()
              glibc 2.4.  POSIX.1-2008.

SEE ALSO

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