mkfifoat

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:
               _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 5.01 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/.




GNU                               2017-09-15                         MKFIFO(3)