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)):
mkfifoat():
- Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
_ATFILE_SOURCE
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.
One of the directories in pathname
did not allow search (execute) permission.
The user's quota of disk blocks or inodes on the filesystem has been exhausted.
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.
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 directory.
pathname
refers to a read-only filesystem.
The following additional errors can occur for mkfifoat():
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.
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value |
mkfifo(), mkfifoat() | Thread safety | MT-Safe |
This page is part of release 5.10 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/.