int mkdir(const char *path, mode_t mode);
int mkdirat(int fd, const char *path, mode_t mode);
IEEE Std 1003.1-2017
mkdir() function shall create a new directory with name path. The file permission bits of the new directory
shall be initialized from mode. These file permission bits of the mode argument shall be modified by the process'
file creation mask.
When bits in mode other than the file permission bits are set, the meaning of these additional bits is implementation-defined.
The directory's user ID shall be set to the process' effective user ID. The directory's group ID shall be set to the group ID of the parent directory or to the effective group ID of the process. Implementations shall provide a way to initialize the directory's group ID to the group ID of the parent directory. Implementations may, but need not, provide an implementation-defined way to initialize the directory's group ID to the effective group ID of the calling process.
The newly created directory shall be an empty directory.
If path names a symbolic link,
mkdir() shall fail and set errno to
Upon successful completion,
mkdir() shall mark for update the last data access, last data modification, and last file
status change timestamps of the directory. Also, the last data modification and last file status change timestamps of the directory
that contains the new entry shall be marked for update.
mkdirat() function shall be equivalent to the
mkdir() function except in the case where path specifies
a relative path. In this case the newly created directory is created relative to the directory associated with the file descriptor
fd instead of the current working directory. If the access mode of the open file description associated with the file
descriptor is not
O_SEARCH, the function shall check whether directory searches are permitted using the current permissions of the
directory underlying the file descriptor. If the access mode is
O_SEARCH, the function shall not perform the check.
mkdirat() is passed the special value
AT_FDCWD in the fd parameter, the current working directory shall be used
and the behavior shall be identical to a call to
Upon successful completion, these functions shall return
0. Otherwise, these functions shall return
-1 and set
indicate the error. If
-1 is returned, no directory shall be created.
These functions shall fail if:
EACCES- Search permission is denied on a component of the path prefix, or write permission is denied on the parent directory of the directory to be created.
EEXIST- The named file exists.
ELOOP- A loop exists in symbolic links encountered during resolution of the path argument.
EMLINK- The link count of the parent directory would exceed
ENAMETOOLONG- The length of a component of a pathname is longer than
ENOENT- A component of the path prefix specified by path does not name an existing directory or path is an empty string.
ENOSPC- The file system does not contain enough space to hold the contents of the new directory or to extend the parent directory of the new directory.
ENOTDIR- A component of the path prefix names an existing file that is neither a directory nor a symbolic link to a directory.
EROFS- The parent directory resides on a read-only file system.
In addition, the
mkdirat() function shall fail if:
EACCES- The access mode of the open file description associated with fd is not O_SEARCH and the permissions of the directory underlying fd do not permit directory searches.
EBADF- The path argument does not specify an absolute path and the fd argument is neither
AT_FDCWDnor a valid file descriptor open for reading or searching.
ENOTDIR- The path argument is not an absolute path and fd is a file descriptor associated with a non-directory file.
These functions may fail if:
ELOOP- More than
SYMLOOP_MAXsymbolic links were encountered during resolution of the path argument.
ENAMETOOLONG- The length of a pathname exceeds
PATH_MAX, or pathname resolution of a symbolic link produced an intermediate result with a length that exceeds