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:
() attempts to create a directory named pathname
The argument mode
specifies the mode for the new directory (see
). 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
& 0777). Whether other mode
are honored for the created directory depends on the operating system. For
Linux, see NOTES 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
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
() system call operates in exactly the same way as
(), 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).
is relative and dirfd
is the special value
, then pathname
is interpreted relative to the current
working directory of the calling process (like mkdir
is absolute, then dirfd
for an explanation of the need for mkdirat
() and mkdirat
() return zero on success, or -1 if an error
occurred (in which case, errno
is set appropriately).
- 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).)
- The user's quota of disk blocks or inodes on the filesystem
has been exhausted.
- pathname already exists (not necessarily as a
directory). This includes the case where pathname is a symbolic
link, dangling or not.
- pathname points outside your accessible address
- The final component ("basename") of the new
directory's pathname is invalid (e.g., it contains characters not
permitted by the underlying filesystem).
- Too many symbolic links were encountered in resolving
- The number of links to the parent directory would exceed
- pathname was too long.
- A directory component in pathname does not exist or
is a dangling symbolic link.
- Insufficient kernel memory was available.
- The device containing pathname has no room for the
- 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.
- The filesystem containing pathname does not support
the creation of directories.
- pathname refers to a file on a read-only
The following additional errors can occur for mkdirat
- dirfd is not a valid file descriptor.
- pathname is relative and dirfd is a file
descriptor referring to a file other than a directory.
() was added to Linux in kernel 2.6.16; library support was added
to glibc in version 2.4.
(): SVr4, BSD, POSIX.1-2001, POSIX.1-2008.
Under Linux, apart from the permission bits, the S_ISVTX mode
is also honored.
There are many infelicities in the protocol underlying NFS. Some of these affect
On older kernels where mkdirat
() is unavailable, the glibc wrapper
function falls back to the use of mkdir
(). When pathname
relative pathname, glibc constructs a pathname based on the symbolic link in
that corresponds to the dirfd
, acl(5) path_resolution(7)
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