MKFIFO(2) BSD System Calls Manual MKFIFO(2)NAME
mkfifo, mkfifoat -- make a fifo file
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int
mkfifo(const char *path, mode_t mode);
int
mkfifoat(int fd, const char *path, mode_t mode);
DESCRIPTION
The mkfifo() system call creates a new fifo file with name path. The access permissions are specified by mode and restricted by the umask(2)
of the calling process.
The fifo's owner ID is set to the process's effective user ID. The fifo's group ID is set to that of the parent directory in which it is
created.
The mkfifoat() system call is equivalent to mkfifo() except in the case where path specifies a relative path. In this case the newly created
FIFO is created relative to the directory associated with the file descriptor fd instead of the current working directory. If mkfifoat() is
passed the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to a call to
mkfifo().
RETURN VALUES
The mkfifo() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
the error.
ERRORS
The mkfifo() system call will fail and no fifo will be created if:
[ENOTSUP] The kernel has not been configured to support fifo's.
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
[ENOENT] A component of the path prefix does not exist.
[EACCES] A component of the path prefix denies search permission, or write permission is denied on the parent directory of the fifo
to be created.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[EROFS] The named file would reside on a read-only file system.
[EEXIST] The named file exists.
[EPERM] The parent directory of the named file has its immutable flag set, see the chflags(2) manual page for more information.
[ENOSPC] The directory in which the entry for the new fifo is being placed cannot be extended because there is no space left on the
file system containing the directory.
[ENOSPC] There are no free inodes on the file system on which the fifo is being created.
[EDQUOT] The directory in which the entry for the new fifo is being placed cannot be extended because the user's quota of disk
blocks on the file system containing the directory has been exhausted.
[EDQUOT] The user's quota of inodes on the file system on which the fifo is being created has been exhausted.
[EIO] An I/O error occurred while making the directory entry or allocating the inode.
[EIO] An I/O error occurred while reading from or writing to the file system.
[EFAULT] The path argument points outside the process's allocated address space.
In addition to the errors returned by the mkfifo(), the mkfifoat() may fail if:
[EBADF] The path argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor
open for searching.
[ENOTDIR] The path argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory.
SEE ALSO chflags(2), chmod(2), mknod(2), stat(2), umask(2)STANDARDS
The mkfifo() system call is expected to conform to ISO/IEC 9945-1:1990 (``POSIX.1''). The mkfifoat() system call follows The Open Group
Extended API Set 2 specification.
HISTORY
The mkfifoat() system call appeared in FreeBSD 8.0.
BSD April 10, 2008 BSD
Check Out this Related Man Page
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 chan-
nel, 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
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latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
GNU 2017-09-15 MKFIFO(3)