Section: Linux Programmer's Manual (3)
mkfifo, mkfifoat - make a FIFO special file (a named pipe)
int mkfifo(const char *pathname, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
int mkfifoat(int dirfd, const char *pathname, mode_t mode);
Feature Test Macro Requirements for glibc (see
- Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
makes a FIFO special file with name pathname
specifies the FIFO's permissions.
It is modified by the
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
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.
for nonblocking handling of FIFO special files.
function operates in exactly the same way as
except for the differences described here.
If the pathname given in
is relative, then it is interpreted relative to the directory
referred to by the file descriptor
(rather than relative to the current working directory of
the calling process, as is done by
for a relative pathname).
is relative and
is the special value
is interpreted relative to the current working
directory of the calling process (like
is absolute, then
In the case of an error, -1 is returned (in which case, errno
is set appropriately).
One of the directories in pathname did not allow search
The user's quota of disk blocks or inodes on the filesystem has been
pathname already exists.
This includes the case where
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.
A directory component in pathname does not exist or is a
dangling symbolic link.
The directory or filesystem has no room for the new file.
A component used as a directory in pathname is not, in fact, a
pathname refers to a read-only filesystem.
The following additional errors can occur for
is not a valid file descriptor.
is a relative path and
is a file descriptor referring to a file other than a directory.
was added to glibc in version 2.4.
It is implemented using
available on Linux since kernel 2.6.16.
For an explanation of the terms used in this section, see
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