MKFIFO(2) System Calls Manual MKFIFO(2)

mkfifo, mkfifoat — make a fifo file

Standard C Library (libc, -lc)

#include <sys/stat.h>

int
mkfifo(const char *path, mode_t mode);

#include <sys/stat.h>
#include <fcntl.h>

int
mkfifoat(int fd, const char *path, mode_t mode);

() 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.

() works the same way as mkfifo() except if path is relative. In that case, it is looked up from a directory whose file descriptor was passed as fd. Search permission is required on this directory. fd can be set to AT_FDCWD in order to specify the current directory.

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 mkfifo() and mkfifoat() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

mkfifo() and mkfifoat() will fail and no fifo will be created if:

[]
Search permission is denied for a component of the path prefix.
[]
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. Or, the user's quota of inodes on the file system on which the fifo is being created has been exhausted.
[]
The named file exists.
[]
path points outside the process's allocated address space.
[]
An I/O error occurred while making the directory entry or allocating the inode. Or, an I/O error occurred while reading from or writing to the file system.
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Too many symbolic links were encountered in translating the pathname.
[]
A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
[]
A component of the path prefix does not exist.
[]
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. Or, there are no free inodes on the file system on which the fifo is being created.
[]
A component of the path prefix is not a directory.
[]
The kernel has not been configured to support fifo's.
[]
The named file resides on a read-only file system.

In addition, mkfifoat() will fail if:

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path does not specify an absolute path and fd is neither AT_FDCWD nor a valid file descriptor open for reading or searching.
[]
path is not an absolute path and fd is a file descriptor associated with a non-directory file.

chmod(2), stat(2), umask(2)

The mkfifo function call conforms to IEEE Std 1003.1-1990 (“POSIX.1”). mkfifoat() conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

July 29, 2013 NetBSD 11.0