MKDIR(2) System Calls Manual MKDIR(2)

mkdir, mkdirat — make a directory file

Standard C Library (libc, -lc)

#include <sys/stat.h>

int
mkdir(const char *path, mode_t mode);

#include <sys/stat.h>
#include <fcntl.h>

int
mkdirat(int fd, const char *path, mode_t mode);

The directory path is created with the access permissions specified by mode and restricted by the umask(2) of the calling process. On NetBSD all other mode bits (S_ISUID, S_ISGID, S_ISTXT) are ignored. This is implementation defined; for example on Linux S_ISTXT is honored.

() works the same way as () except if path is relative. In that case, it is looked up from a directory whose file descriptor was passed as fd. Search permission is required this directory. fd can be set to AT_FDCWD in order to specify the current directory.

The directory's owner ID is set to the process's effective user ID. The directory's group ID is set to that of the parent directory in which it is created.

The mkdir() and mkdirat() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

Both mkdir() and mkdirat() will fail and no directory will be created if:

[]
Search permission is denied for a component of the path prefix.
[]
The new directory cannot be created because the user's quota of disk blocks on the file system that will contain the directory has been exhausted. Or, the user's quota of inodes on the file system on which the directory is being created has been exhausted.
[]
The named file exists.
[]
path points outside the process's allocated address space.
[]
An I/O error occurred while making the directory entry or allocating the inode; or an I/O error occurred while reading from or writing to the file system.
[]
Too many symbolic links were encountered in translating the pathname.
[]
A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
[]
A component of the path prefix does not exist.
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The new directory cannot be created because there is no space left on the file system that will contain the directory. Or, there are no free inodes on the file system on which the directory is being created.
[]
A component of the path prefix is not a directory.
[]
The named file resides on a read-only file system.

In addition, mkdirat() will fail if:

[]
path does not specify an absolute path and fd is neither AT_FDCWD nor a valid file descriptor open for reading or searching.
[]
path is not an absolute path and fd is a file descriptor associated with a non-directory file.

chmod(2), stat(2), umask(2)

The mkdir() function conforms to IEEE Std 1003.1-1990 (“POSIX.1”). mkdirat() conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

The mkdir() function appeared in Version 1 AT&T UNIX.

February 4, 2020 NetBSD 11.0