MKNOD(2) Linux Programmer's Manual MKNOD(2)
mknod - create a special or ordinary file
int mknod(const char *pathname, mode_t mode, dev_t dev);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
The system call mknod() creates a file system node (file, device special file or named
pipe) named pathname, with attributes specified by mode and dev.
The mode argument specifies both the permissions to use and the type of node to be cre-
ated. 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 must be one of S_IFREG, S_IFCHR, S_IFBLK, S_IFIFO or S_IFSOCK to specify a
regular 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
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 (makedev(3) may be useful to build the value for
dev); 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 file system 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.
mknod() returns zero on success, or -1 if an error occurred (in which case, errno is set
EACCES The parent directory does not allow write permission to the process, or one of the
directories in the path prefix of pathname did not allow search permission. (See
EDQUOT The user's quota of disk blocks or inodes on the file system has been exhausted.
EEXIST pathname already exists. This includes the case where pathname is a symbolic link,
dangling or not.
EFAULT pathname points outside your accessible address space.
EINVAL mode requested creation of something other than a regular file, device special
file, FIFO or socket.
ELOOP Too many symbolic links were encountered in resolving pathname.
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.
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 file system containing pathname does
not support the type of node requested.
EROFS pathname refers to a file on a read-only file system.
SVr4, 4.4BSD, POSIX.1-2001 (but see below).
POSIX.1-2001 says: "The only portable use of mknod() is to create a FIFO-special file. If
mode is not S_IFIFO or dev is not 0, the behavior of mknod() is unspecified." However,
nowadays one should never use mknod() for this purpose; one should use mkfifo(3), a func-
tion especially defined for this purpose.
Under Linux, this call cannot be used to create directories. One should make directories
There are many infelicities in the protocol underlying NFS. Some of these affect mknod().
chmod(2), chown(2), fcntl(2), mkdir(2), mknodat(2), mount(2), socket(2), stat(2),
umask(2), unlink(2), makedev(3), mkfifo(3), path_resolution(7)
This page is part of release 3.53 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
Linux 2013-01-27 MKNOD(2)