NAME
mknod - create a special or ordinary file
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
I int mknod(const char * pathname , mode_t mode , dev_t dev );
DESCRIPTION
The system call
R mknod ()
creates a filesystem node (file, device special file or
named pipe) named
R pathname ,
with attributes specified by
mode
and
R dev .
The
mode
argument 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
R umask
in the usual way: the permissions of the created node are
R (mode & ~umask) .
The file type must be one of
R S_IFREG ,
R S_IFCHR ,
R S_IFBLK ,
R S_IFIFO
or
R S_IFSOCK
to specify a normal file (which will be created empty), character
special file, block special file, FIFO (named pipe), or Unix domain socket,
respectively.
(Zero file type is equivalent to type
R S_IFREG .)
If the file type is
R 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 symbolic link, this call fails with an
EEXIST
error.
The newly created node will be owned by the effective user ID 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 group ID of the process.
RETURN VALUE
R mknod ()
returns zero on success, or -1 if an error occurred (in which case,
errno
is set appropriately).
ERRORS
EACCES
The parent directory does not allow write permission to the process,
or one of the directories in the path prefix of
R pathname
did not allow search permission.
(See also
path_resolution(7).)
EEXIST
pathname
already exists.
EFAULT
R pathname points outside your accessible address space.
EINVAL
mode
requested creation of something other than a normal file, device
special file, FIFO or socket.
ELOOP
Too many symbolic links were encountered in resolving
R pathname .
ENAMETOOLONG
R pathname was too long.
ENOENT
A directory component in
pathname
does not exist or is a dangling symbolic link.
ENOMEM
Insufficient kernel memory was available.
ENOSPC
The device containing
pathname
has no room for the new node.
ENOTDIR
A component used as a directory in
pathname
is not, in fact, a directory.
EPERM
mode
requested creation of something other than a regular file,
FIFO (named pipe), or Unix domain socket, and the caller
is not privileged (Linux: does not have the
CAP_MKNOD
capability);
also returned if the filesystem containing
pathname
does not support the type of node requested.
EROFS
pathname
refers to a file on a read-only filesystem.
CONFORMING TO
SVr4, 4.4BSD, POSIX.1-2001 (but see below).
NOTES
POSIX.1-2001 says: "The only portable use of
R mknod ()
is to create a FIFO-special file.
If
mode
is not S_IFIFO or
dev
is not 0, the behavior of
R mknod ()
is unspecified."
Under Linux, this call cannot be used to create directories.
One should make directories with
mkdir(2),
and FIFOs with
mkfifo(3).
There are many infelicities in the protocol underlying NFS.
Some of these affect
R mknod ().
SEE ALSO
ČLÁNKY DO MAILU