From Linux Man Pages
mkfifo - 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);
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 file system 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 non-blocking handling of FIFO special files.
RETURN VALUE
On success mkfifo() returns 0. In the case of an error, -1 is returned (in which case, errno is set appropri-
ately).
ERRORS
EACCES One of the directories in pathname did not allow search (execute) permission.
EEXIST pathname already exists.
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 file systems 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.
CONFORMING TO
POSIX.1-2001.
RELATED
mkfifo(1), close(2), open(2), read(2), stat(2), umask(2), write(2), mkfifoat(3), fifo(7)
CATEGORY