MKDIR(2) Linux Programmer's Manual MKDIR(2)
mkdir, mkdirat - create a directory
int mkdir(const char *pathname, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
int mkdirat(int dirfd, const char *pathname, mode_t mode);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
mkdir() attempts to create a directory named pathname.
The argument mode specifies the mode for the new directory (see
inode(7)). It is modified by the process's umask in the usual way: in
the absence of a default ACL, the mode of the created directory is
(mode & ~umask & 0777). Whether other mode bits are honored for the
created directory depends on the operating system. For Linux, see
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.
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().
mkdir() and mkdirat() return 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).)
EDQUOT The user's quota of disk blocks or inodes on the filesystem has
EEXIST pathname already exists (not necessarily as a directory). This
includes the case where pathname is a symbolic link, dangling or
EFAULT pathname points outside your accessible address space.
EINVAL The final component ("basename") of the new directory's pathname
is invalid (e.g., it contains characters not permitted by the
ELOOP Too many symbolic links were encountered in resolving pathname.
EMLINK The number of links to the parent directory would exceed
pathname was too long.
ENOENT A directory component in pathname does not exist or is a dan-
gling symbolic link.
ENOMEM Insufficient kernel memory was available.
ENOSPC The device containing pathname has no room for the new direc-
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
EPERM The filesystem containing pathname does not support the creation
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.
pathname is relative and dirfd is a file descriptor referring to
a file other than a directory.
mkdirat() was added to Linux in kernel 2.6.16; library support was
added to glibc in version 2.4.
mkdir(): SVr4, BSD, POSIX.1-2001, POSIX.1-2008.
Under Linux, apart from the permission bits, the S_ISVTX mode bit is
There are many infelicities in the protocol underlying NFS. Some of
these affect mkdir().
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.
mkdir(1), chmod(2), chown(2), mknod(2), mount(2), rmdir(2), stat(2),
umask(2), unlink(2), acl(5) path_resolution(7)
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