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MKDIR(2) Linux Programmer's Manual MKDIR(2)
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 dif‐
ferences 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 inter‐
preted 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_resolu‐
tion(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 ver‐
sion 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 3.74 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/.
Linux 2014-08-19 MKDIR(2)
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