mkfifoat(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 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.

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 4.09 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/.

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