View Source: mknod(2) - Waikato Linux Users Group

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!!NAME
mknod - create a special or ordinary file
!!SYNOPSIS
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>

 __int mknod(const char *__''pathname''__, mode_t __''mode''__, dev_t__'' dev''__);__

!!DESCRIPTION
mknod(2) attempts to create a filesystem node (file, device special file or named pipe) named ''pathname'', specified by ''mode'' and ''dev''.

''mode'' specifies both the permissions to use and the type of node to be created.

It should be a combination (using bitwise OR) of one of the file types listed below and the permissions for the new node.

The permissions are modified by the process's __umask__ in the usual way: the permissions of the created node are __(mode & ~umask)__.

The file type should be one of __S_IFREG__, __S_IFCHR__, __S_IFBLK__ and __S_IFIFO__ to specify a normal file (which will be created empty), character special file, block special file or FIFO (named pipe), respectively, or zero, which will create a normal file.

If the file type is __S_IFCHR__ or __S_IFBLK__ then ''dev'' specifies the major and minor numbers of the newly created device special file; otherwise it is
ignored.

If ''pathname'' already exists, or is a symlink, this call fails with an [EEXIST] error.

The newly created node will be owned by the effective uid of the process. If the directory containing the node has the set group id bit set, or if the filesystem is mounted with BSD group semantics, the new node will inherit the group ownership from its parent directory; otherwise it will be owned by the effective gid of the process.

!!RETURN VALUE
mknod(2) returns zero on success, or -1 if an error occurred (in which case, ''errno'' is set appropriately).

!!ERRORS
;[EPERM]: ''mode'' requested creation of something other than a FIFO (named pipe), and the caller is not the superuser; also returned if the filesystem containing ''pathname'' does not support the type of node requested.
;[EINVAL]: ''mode'' requested creation of something other than a normal file, device special file or FIFO.
;[EEXIST]: ''pathname'' already exists.
;[EFAULT]: ''pathname'' points outside your accessible address space.
;[EACCES]: The parent directory does not allow write permission to the process, or one of the directories in ''pathname'' did not allow search (execute) permission.
;[ENAMETOOLONG]: ''pathname'' was too long.
;[ENOENT]: A directory component in ''pathname'' does not exist or is a dangling symbolic link.
;[ENOTDIR]: A component used as a directory in ''pathname'' is not, in fact, a directory.
;[ENOMEM]: Insufficient kernel memory was available.
;[EROFS]: ''pathname'' refers to a file on a read-only filesystem.
;[ELOOP]: Too many symbolic links were encountered in resolving ''pathname''.
;[ENOSPC]: The device containing ''pathname'' has no room for the new node.

!!CONFORMING TO
SVr4 (but the call requires privilege and is thus not in POSIX), 4.4BSD. The Linux version differs from the SVr4 version in that it does not require root permission to
create pipes, also in that no [EMULTIHOP], [ENOLINK], or [EINTR] error is documented.

!!NOTES
POSIX 1003.1&#8208;2001 says: "The only portable use of mknod() is to create a FIFO&#8208;special file. If mode is not S_IFIFO or dev is not 0, the behavior of mknod() is unspecified."

Under Linux, this call cannot be used to create directories or socket files, and cannot be used to create normal files by users other than the superuser. One should make directories with mkdir(2), and FIFOs with mkfifo(2).

There are many infelicities in the protocol underlying NFS. Some of these affect mknod(2).

!!SEE ALSO
close(2), fcntl(2), mkdir(2), mount(2), open(2), read(2), socket(2), stat(2), umask(2), unlink(2), write(2), fopen(3), mkfifo(3)
10 pages link to mknod(2):
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Last edited on Monday, March 10, 2003 3:23:53 pm by PerryLorier
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