MKFIFO(3C) Standard C Library Functions MKFIFO(3C)


NAME


mkfifo, mkfifoat - make a FIFO special file

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() and mkfifoat() functions create a new FIFO special file
named by the pathname pointed to by path. The file permission bits of
the new FIFO are initialized from mode. The file permission bits of the
mode argument are modified by the process's file creation mask (see
umask(2)). Bits other than the file permission bits in mode are ignored.


If path names a symbolic link, mkfifo() and mkfifoat() fail and set errno
to EEXIST.


The FIFO's user ID is set to the process's effective user ID. The FIFO's
group ID is set to the group ID of the parent directory or to the
effective group ID of the process.


The mkfifoat() function is equivalent to mkfifo(); however, if path is a
relative path, then it is resolved start at the directory represented by
fd. fd may be set to the special value of AT_FDCWD which indicates that
the current working directory should be used to start resolving path.


The mkfifo() function calls mknod(2) to create the file. The mkfifoat()
function calls mknodat(2) to create the file.


Upon successful completion, mkfifo() and mkfifoat() mark for update the
st_atime, st_ctime, and st_mtime fields of the file. Also, the st_ctime
and st_mtime fields of the directory that contains the new entry are
marked for update.

RETURN VALUES


Upon successful completion, 0 is returned. Otherwise, -1 is returned and
errno is set to indicate the error.

ERRORS


The mkfifo() and mkfifoat() functions will fail if:

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.


EEXIST
The named file already exists.


ELOOP
A loop exists in symbolic links encountered during
resolution of the path argument.


ENAMETOOLONG
The length of the path argument exceeds {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.


ENOENT
A component of the path prefix specified by path does not
name an existing directory or path is an empty string.


ENOSPC
The directory that would contain the new file cannot be
extended or the file system is out of file-allocation
resources.


ENOTDIR
A component of the path prefix is not a directory. For
mkfifoat(), path is a relative path and fd is a valid
file descriptor which is not a directory.


EROFS
The named file resides on a read-only file system.


The mkfifoat() function will fail if:

EBADF
The path argument is a relative path and fd is not a
valid file descriptor or the value AT_FDCWD.


The mkfifo() function may fail if:

ELOOP
Too many symbolic links were encountered in resolving
path.


ENAMETOOLONG
The length of the path argument exceeds {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.


EXAMPLES


Example 1: Create a FIFO File




The following example demonstrates how to create a FIFO file named
/home/cnd/mod_done with read and write permissions for the owner and read
permissions for the group and others.


#include sys/types.h>
#include sys/stat.h>
int status;
...
status = mkfifo("/home/cnd/mod_done", S_IWUSR | S_IRUSR |
S_IRGRP | S_IROTH);


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO


mkdir(1), chmod(2), exec(2), mknod(2), umask(2), stat.h(3HEAD), ufs(7FS),
attributes(5), standards(5)


April 24, 2002 MKFIFO(3C)