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);

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.

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.

VERSIONS¶

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

ATTRIBUTES¶

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

STANDARDS¶

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)