mknod
, mknodat
—
make a special file node
Standard C Library (libc, -lc)
#include <sys/stat.h>
int
mknod
(const
char *path, mode_t
mode, dev_t
dev);
#include
<sys/stat.h>
#include <fcntl.h>
int
mknodat
(int
fd, const char
*path, mode_t mode,
dev_t dev);
The device special file path is created with the major and
minor device numbers specified by dev. The access
permissions of path are extracted from
mode, modified by the
umask(2) of the parent process.
mknodat
() works the same way as
mknod
() 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.
mknod
() requires super-user
privileges.
The mknod
() and mknodat
()
functions return the value 0 if successful; otherwise the
value -1 is returned and the global variable
errno is set to indicate the error.
mknod
() and mknodat
() will fail
and the file will be not created if:
- [
EACCES
]
- Search permission is denied for a component of the path prefix.
- [
EDQUOT
]
- The directory in which the entry for the new node 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 node is being created has been
exhausted.
- [
EEXIST
]
- The named file exists.
- [
EFAULT
]
- path points outside the process's allocated address
space.
- [
EINVAL
]
- The supplied mode or dev is
invalid.
- [
EIO
]
- An I/O error occurred while making the directory entry or allocating the
inode.
- [
ELOOP
]
- Too many symbolic links were encountered in translating the pathname.
- [
ENAMETOOLONG
]
- A component of a pathname exceeded {
NAME_MAX
}
characters, or an entire path name exceeded
{PATH_MAX
} characters.
- [
ENOENT
]
- A component of the path prefix does not exist.
- [
ENOSPC
]
- The directory in which the entry for the new node 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
node is being created.
- [
ENOTDIR
]
- A component of the path prefix is not a directory.
- [
EPERM
]
- The process's effective user ID is not super-user.
- [
EROFS
]
- The named file resides on a read-only file system.
In addition, mknodat
() will fail if:
- [
EBADF
]
- path does not specify an absolute path and
fd is neither
AT_FDCWD
nor a
valid file descriptor open for reading or searching.
- [
ENOTDIR
]
- path is not an absolute path and
fd is a file descriptor associated with a
non-directory file.
The mknod
() function conforms to IEEE
Std 1003.1-1990 (“POSIX.1”).
mknodat
() conforms to IEEE Std
1003.1-2008 (“POSIX.1”).
A mknod
() function call appeared in
Version 6 AT&T UNIX.