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


       #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)):

           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:


       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.

       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.


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


       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.

              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

       EROFS  pathname refers to a read-only filesystem.

       The following additional errors can occur for mkfifoat():

       EBADF  dirfd is not a valid file descriptor.

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


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


       For   an   explanation   of   the  terms  used  in  this  section,  see

       │InterfaceAttributeValue   │
       │mkfifo(), mkfifoat() │ Thread safety │ MT-Safe │


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

       mkfifoat(): POSIX.1-2008.


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


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