mkdir, mkdirat - create a directory
#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)):
- Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
mkdir() attempts to create a directory named
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 & ~
& 0777). Whether other
mode bits are honored for the
created directory depends on the operating system. For Linux, see NOTES
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.
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
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
pathname is absolute, then
dirfd is ignored.
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 space.
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 LINK_MAX.
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 new
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,
The filesystem containing
pathname does not support the
creation of directories.
pathname refers to a file on a read-only filesystem.
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.
Under Linux, apart from the permission bits, the
mode bit is also honored.
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
pathname is a relative pathname,
glibc constructs a pathname based on the symbolic link in
/proc/self/fd that corresponds to the
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