MKNOD(2) BSD System Calls Manual MKNOD(2)NAME
mknod, mknodat — make a special file node
Standard C Library (libc, -lc)
mknod(const char *path, mode_t mode, dev_t dev);
mknodat(int fd, const char *path, mode_t mode, dev_t dev);
The file system node path is created with the file type and access per‐
missions specified in mode. The access permissions are modified by the
process's umask value.
If mode indicates a block or character special file, dev is a configura‐
tion dependent specification denoting a particular device on the system.
Otherwise, dev is ignored.
The mknod() system call requires super-user privileges.
The mknodat() system call is equivalent to mknod() except in the case
where path specifies a relative path. In this case the newly created
device node is created relative to the directory associated with the file
descriptor fd instead of the current working directory. If mknodat() is
passed the special value AT_FDCWD in the fd parameter, the current work‐
ing directory is used and the behavior is identical to a call to mknod().
The mknod() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
The mknod() system call will fail and the file will be not created if:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or
an entire path name exceeded 1023 characters.
[ENOENT] A component of the path prefix does not exist.
[EACCES] Search permission is denied for a component of the
[ELOOP] Too many symbolic links were encountered in translat‐
ing the pathname.
[EPERM] The process's effective user ID is not super-user.
[EIO] An I/O error occurred while making the directory entry
or allocating the inode.
[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 direc‐
[ENOSPC] There are no free inodes on the file system on which
the node is being created.
[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.
[EDQUOT] The user's quota of inodes on the file system on which
the node is being created has been exhausted.
[EROFS] The named file resides on a read-only file system.
[EEXIST] The named file exists.
[EFAULT] The path argument points outside the process's allo‐
cated address space.
[EINVAL] Creating anything else than a block or character spe‐
cial file (or a whiteout) is not supported.
In addition to the errors returned by the mknod(), the mknodat() may fail
[EBADF] The path argument does not specify an absolute path
and the fd argument is neither AT_FDCWD nor a valid
file descriptor open for searching.
[ENOTDIR] The path argument is not an absolute path and fd is
neither AT_FDCWD nor a file descriptor associated with
SEE ALSOchmod(2), mkfifo(2), stat(2), umask(2)STANDARDS
The mknodat() system call follows The Open Group Extended API Set 2 spec‐
The mknod() function appeared in Version 6 AT&T UNIX. The mknodat() sys‐
tem call appeared in FreeBSD 8.0.
BSD April 10, 2008 BSD