mkfifo(3C)
NAME
mkfifo - make a FIFO special file
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int mkfifo(const char *path, mode_t mode);
DESCRIPTION
The mkfifo() function creates 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() fails and sets 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 mkfifo() function calls mknod(2) to create the file.
Upon successful completion, mkfifo() marks 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 con-
tains 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() function will fail if:
EACCES
A component of the path prefix denies search permis-
sion, 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.
EROFS The named file resides on a read-only file system.
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}.
USAGE
When a UFS file system is mounted with logging enabled, file
system transactions that free blocks from files might not
actually add those freed blocks to the file system's free
list until some unspecified time in the future. This
behavior improves file system performance but does not con-
form to the POSIX, Single UNIX Specification, SPARC Confor-
mance Definition, System V Application Binary Interface,
System V Interface Definition, and X/Open Portability Guide
Standards, which require that freed space be available
immediately. To enable standards conformance regarding file
deletions or to address the problem of not being able to
grow files on a relatively full UFS file system even after
files have been deleted, disable UFS logging (see
mount_ufs(1M).
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 attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Standard |
|_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
SEE ALSO
mkdir(1), mount_ufs(1M), chmod(2), exec(2), mknod(2),
umask(2), stat(3HEAD), ufs(7FS), attributes(5), standards(5)
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