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(7) 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(4FS),
attributes(7),
standards(7) June 18, 2021 MKFIFO(3C)
