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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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mkdir(2) System Calls Manual mkdir(2)
mkdir, mkdirat - create a directory
Standard C library (libc, -lc)
#include <sys/stat.h>
int mkdir(const char *path, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
#include <sys/stat.h>
int mkdirat(int dirfd, const char *path, mode_t mode);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
mkdirat():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_ATFILE_SOURCE
mkdir() attempts to create a directory named path.
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 VERSIONS 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 path 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 path is relative and dirfd is the special value AT_FDCWD, then
path is interpreted relative to the current working directory of
the calling process (like mkdir()).
If path is absolute, then dirfd is ignored.
See openat(2) for an explanation of the need for mkdirat().
mkdir() and mkdirat() return zero on success. On error, -1 is
returned and errno is set to indicate the error.
EACCES The parent directory does not allow write permission to the
process, or one of the directories in path did not allow
search permission. (See also path_resolution(7).)
EBADF (mkdirat()) path is relative but dirfd is neither AT_FDCWD
nor a valid file descriptor.
EDQUOT The user's quota of disk blocks or inodes on the filesystem
has been exhausted.
EEXIST path already exists (not necessarily as a directory). This
includes the case where path is a symbolic link, dangling
or not.
EFAULT path points outside your accessible address space.
EINVAL The final component ("basename") of the new directory's
path is invalid (e.g., it contains characters not permitted
by the underlying filesystem).
ELOOP Too many symbolic links were encountered in resolving path.
EMLINK The number of links to the parent directory would exceed
LINK_MAX.
ENAMETOOLONG
path was too long.
ENOENT A directory component in path does not exist or is a
dangling symbolic link.
ENOMEM Insufficient kernel memory was available.
ENOSPC The device containing path 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 path is not, in fact, a
directory.
ENOTDIR
(mkdirat()) path is relative and dirfd is a file descriptor
referring to a file other than a directory.
EPERM The filesystem containing path does not support the
creation of directories.
EROFS path refers to a file on a read-only filesystem.
EOVERFLOW
UID or GID mappings (see user_namespaces(7)) have not been
configured.
Under Linux, apart from the permission bits, the S_ISVTX mode bit
is also honored.
glibc notes
On older kernels where mkdirat() is unavailable, the glibc wrapper
function falls back to the use of mkdir(). When path is relative,
glibc constructs a pathname based on the symbolic link in
/proc/self/fd that corresponds to the dirfd argument.
POSIX.1-2008.
mkdir()
SVr4, BSD, POSIX.1-2001.
mkdirat()
Linux 2.6.16, glibc 2.4.
There are many infelicities in the protocol underlying NFS. Some
of these affect mkdir().
mkdir(1), chmod(2), chown(2), mknod(2), mount(2), rmdir(2),
stat(2), umask(2), unlink(2), acl(5), path_resolution(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-05-17 mkdir(2)
Pages that refer to this page: mkdir(1), chmod(2), chown(2), fanotify_mark(2), F_NOTIFY(2const), io_uring_enter2(2), io_uring_enter(2), mknod(2), open(2), rmdir(2), seccomp_unotify(2), syscalls(2), umask(2), io_uring_prep_mkdir(3), io_uring_prep_mkdirat(3), mkdtemp(3), mode_t(3type), proc_pid_attr(5), cpuset(7), inotify(7), signal-safety(7), mount(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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