mkdir - create a directory
int mkdir(const char *pathname, mode_t mode);
mkdir() attempts to create a directory named pathname.
The argument mode specifies the permissions to use. It is modified by the process's umask in the usual way: the permissions of the created directory are (mode & ~umask & 0777). Other mode bits of the created directory depend on the operating system. For Linux, see below.
The newly created directory will be owned by the effective user ID of the process. If the directory containing the file has the set-group-ID bit set, or if the file system is mounted with BSD group semantics (mount -o bsdgroups or, synonymously mount -o grpid), the new directory will inherit the group ownership from its parent; otherwise it will be owned by the effective group ID of the process.
If the parent directory has the set-group-ID bit set then so will the newly created directory.
mkdir() returns zero on success, or -1 if an error occurred (in which case, errno is set appropriately).
EACCES The parent directory does not allow write permission to the process, or one of the directories in pathname did not allow search permission. (See also path_resolution(7).)
EEXIST pathname already exists (not necessarily as a directory). This includes the case where pathname is a symbolic link, dangling or not.
EFAULT pathname points outside your accessible address space.
ELOOP Too many symbolic links were encountered in resolving pathname.
EMLINK The number of links to the parent directory would exceed LINK_MAX.
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 directory.
ENOSPC The new directory cannot be created because the user's disk quota is exhausted.
A component used as a directory in pathname is not, in fact, a directory.
EPERM The file system containing pathname does not support the creation of directories.
EROFS pathname refers to a file on a read-only file system.
SVr4, BSD, POSIX.1-2001.
Under Linux apart from the permission bits, only the S_ISVTX mode bit is honored. That is, under Linux the created directory actually gets mode (mode & ~umask & 01777). See also stat(2).
There are many infelicities in the protocol underlying NFS. Some of these affect mkdir().
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