The mkdir() function creates a new directory named by the path name pointed to by path. The mode of the new directory is initialized from mode (see chmod(2) for values of mode). The protection part of the mode argument is modified by the process's file creation mask (see umask(2)).

The directory's owner ID is set to the process's effective user ID. The directory's group ID is set to the process's effective group ID, or if the S_ISGID bit is set in the parent directory, then the group ID of the directory is inherited from the parent. The S_ISGID bit of the new directory is inherited from the parent directory.

If path is a symbolic link, it is not followed.

The newly created directory is empty with the exception of entries for itself (.) and its parent directory (..).

Upon successful completion, mkdir() marks for update the st_atime, st_ctime and st_mtime fields of the directory. Also, the st_ctime and st_mtime fields of the directory that contains the new entry are marked for update.

Upon successful completion, 0 is returned. Otherwise, -1 is returned, no directory is created, and errno is set to indicate the error.

The mkdir() function will fail if:

EACCES

Either a component of the path prefix denies search permission or write permission is denied on the parent directory of the directory to be created.

EDQUOT

The directory where the new file entry is being placed cannot be extended because the user's quota of disk blocks on that file system has been exhausted; the new directory cannot be created because the user's quota of disk blocks on that file system has been exhausted; or the user's quota of inodes on the file system where the file is being created has been exhausted.

EEXIST

The named file already exists.

EFAULT

The path argument points to an illegal address.

EINVAL

An attempt was made to create an extended attribute that is a directory.

EIO

An I/O error has occurred while accessing the file system.

ELOOP

Too many symbolic links were encountered in translating path.

EMLINK

The maximum number of links to the parent directory would be exceeded.

ENAMETOOLONG

The length of the path argument exceeds PATH_MAX, or the length of a path component exceeds NAME_MAX while _POSIX_NO_TRUNC is in effect.

ENOENT

A component of the path prefix does not exist or is a null pathname.

ENOLINK

The path argument points to a remote machine and the link to that machine is no longer active.

ENOSPC

No free space is available on the device containing the directory.

ENOTDIR

A component of the path prefix is not a directory.

EROFS

The path prefix resides on a read-only file system.

See attributes(5) for descriptions of the following attributes:

chmod(2), mknod(2), umask(2), stat(3HEAD), attributes(5)