[Go to CFHT Home Page] Man Pages
Back to Software Index  BORDER=0Manpage Top Level
    MKDIR(2) manual page Table of Contents

Name

mkdir, mkdirat - create a directory

Synopsis


#include <sys/stat.h>#include <sys/types.h>
int mkdir(const char *pathname, mode_t mode);
#include <fcntl.h>           /* Definition of AT_* constants */#include <sys/stat.h>
int mkdirat(int dirfd, const char *pathname, mode_t mode);

Feature Test Macro Requirements for glibc (see feature_test_macros(7) ):

mkdirat():

Since glibc 2.10:
_XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_ATFILE_SOURCE

Description

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 filesystem 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.

mkdirat()

The mkdirat() system call operates in exactly the same way as mkdir(), except for the differences described here.

If the pathname given in pathname is relative, then it is interpreted relative to the directory referred to by the file descriptor dirfd (rather than relative to the current working directory of the calling process, as is done by mkdir() for a relative pathname).

If pathname is relative and dirfd is the special value AT_FDCWD, then pathname is interpreted relative to the current working directory of the calling process (like mkdir()).

If pathname is absolute, then dirfd is ignored.

See openat(2) for an explanation of the need for mkdirat().

Return Value

mkdir() and mkdirat() return zero on success, or -1 if an error occurred (in which case, errno is set appropriately).

Errors

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) .)
EDQUOT
The user’s quota of disk blocks or inodes on the filesystem has been exhausted.
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.
ENAMETOOLONG
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.
ENOTDIR
A component used as a directory in pathname is not, in fact, a directory.
EPERM
The filesystem containing pathname does not support the creation of directories.
EROFS
pathname refers to a file on a read-only filesystem.

The following additional errors can occur for mkdirat():

EBADF
dirfd is not a valid file descriptor.
ENOTDIR
pathname is relative and dirfd is a file descriptor referring to a file other than a directory.

Versions

mkdirat() was added to Linux in kernel 2.6.16; library support was added to glibc in version 2.4.

Conforming to

mkdir(): SVr4, BSD, POSIX.1-2001, POSIX.1-2008.

mkdirat(): POSIX.1-2008.

Notes

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().

Glibc notes

On older kernels where mkdirat() is unavailable, the glibc wrapper function falls back to the use of mkdir(). When pathname is a relative pathname, glibc constructs a pathname based on the symbolic link in /proc/self/fd that corresponds to the dirfd argument.

See Also

mkdir(1) , chmod(2) , chown(2) , mknod(2) , mount(2) , rmdir(2) , stat(2) , umask(2) , unlink(2) , path_resolution(7)

Colophon

This page is part of release 3.78 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.

Table of Contents