--- name: "mknodat" section: "2" platform: "macos" package: "xnu" version: "12377.121.6" release: "macOS 26.5" platforms: ["linux", "freebsd", "macos"] url: "https://new.carta.tech/mknod/2" --- # mknodat(2) make a special file node Part of [mknod(2)](/mknod/2.md). ## NAME **mknod**, **mknodat** – make a special file node ## SYNOPSIS **#include \** *int*\ **mknod**(*const char \*path*, *mode\_t mode*, *dev\_t dev*); *int*\ **mknodat**(*int fd*, *const char \*path*, *mode\_t mode*, *dev\_t dev*); ## DESCRIPTION The device special file *path* is created with the major and minor device numbers extracted from *mode*. The access permissions of *path* are constrained by the [umask(2)](/umask/2.md) of the parent process. If *mode* indicates a block or character special file, *dev* is a configuration-dependent specification of a character or block I/O device and the superblock of the device. If *mode* does not indicate a block special or character special device, *dev* is ignored. **mknod**() 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 fifo file 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 working directory is used and the behavior is identical to a call to **mknod**(). ## RETURN VALUES Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and *errno* is set to indicate the error. ## ERRORS **mknod**() will fail and the file will be not created if: - \[EACCES\] Search permission is denied for a component of the path prefix. - \[EACCES\] Write permission is denied for the parent directory. - \[EDQUOT\] The directory in which the entry for the new node is being placed cannot be extended; the user's quota of disk blocks on the file system containing the directory has been exhausted. - \[EDQUOT\] The user's quota of inodes for 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. - \[EINVAL\] One or more of the arguments is invalid. - \[EIO\] An I/O error occurs while making the directory entry or allocating the inode. - \[ELOOP\] Too many symbolic links were encountered in translating the pathname. This is taken to be indicative of a looping symbolic link. - \[ENAMETOOLONG\] A component of a pathname exceeds {NAME\_MAX} characters or an entire path name exceeds {PATH\_MAX} characters. - \[ENOENT\] A component of the path prefix does not exist or path is an empty string. - \[ENOSPC\] 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. - \[ENOSPC\] 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 created node would reside on a read-only file system. In addition to the errors returned by the **mknod**(), the **mknodat**() function may fail if: - \[EBADF\] 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 a directory. ## LEGACY SYNOPSIS **#include \** The include file has changed. ## SEE ALSO [chmod(2)](/chmod/2.md), [stat(2)](/stat/2.md), [umask(2)](/umask/2.md), [compat(5)](/compat/5.md) ## HISTORY A **mknod**() function call appeared in Version 6 AT&T UNIX. The **mknodat**() system call appeared in macOS 13.0.