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<H1>MKDIR</H1>
Section: Linux Programmer's Manual (2)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
mkdir, mkdirat - create a directory
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/sys/stat.h">sys/stat.h</A>&gt;</B>
<B>#include &lt;<A HREF="file:///usr/include/sys/types.h">sys/types.h</A>&gt;</B>
<B>int mkdir(const char *</B><I>pathname</I><B>, mode_t </B><I>mode</I><B>);</B>
<B>#include &lt;<A HREF="file:///usr/include/fcntl.h">fcntl.h</A>&gt; </B>/* Definition of AT_* constants */
<B>#include &lt;<A HREF="file:///usr/include/sys/stat.h">sys/stat.h</A>&gt;</B>
<B>int mkdirat(int </B><I>dirfd</I><B>, const char *</B><I>pathname</I><B>, mode_t </B><I>mode</I><B>);</B>
</PRE>
<P>
Feature Test Macro Requirements for glibc (see
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
<P>
<B>mkdirat</B>():
<DL COMPACT><DT id="1"><DD>
<DL COMPACT>
<DT id="2">Since glibc 2.10:<DD>
_POSIX_C_SOURCE&nbsp;&gt;=&nbsp;200809L
<DT id="3">Before glibc 2.10:<DD>
_ATFILE_SOURCE
</DL>
</DL>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<B>mkdir</B>()
attempts to create a directory named
<I>pathname</I>.
<P>
The argument
<I>mode</I>
specifies the mode for the new directory (see
<B><A HREF="/cgi-bin/man/man2html?7+inode">inode</A></B>(7)).
It is modified by the process's
<I>umask</I>
in the usual way: in the absence of a default ACL, the mode of the
created directory is
(<I>mode</I> &amp; ~<I>umask</I> &amp; 0777).
Whether other
<I>mode</I>
bits are honored for the created directory depends on the operating system.
For Linux, see NOTES below.
<P>
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
(<I>mount -o bsdgroups</I>
or, synonymously
<I>mount -o grpid</I>),
the new directory will inherit the group ownership from its parent;
otherwise it will be owned by the effective group ID of the process.
<P>
If the parent directory has the set-group-ID bit set, then so will the
newly created directory.
<A NAME="lbAE">&nbsp;</A>
<H3>mkdirat()</H3>
The
<B>mkdirat</B>()
system call operates in exactly the same way as
<B>mkdir</B>(),
except for the differences described here.
<P>
If the pathname given in
<I>pathname</I>
is relative, then it is interpreted relative to the directory
referred to by the file descriptor
<I>dirfd</I>
(rather than relative to the current working directory of
the calling process, as is done by
<B>mkdir</B>()
for a relative pathname).
<P>
If
<I>pathname</I>
is relative and
<I>dirfd</I>
is the special value
<B>AT_FDCWD</B>,
then
<I>pathname</I>
is interpreted relative to the current working
directory of the calling process (like
<B>mkdir</B>()).
<P>
If
<I>pathname</I>
is absolute, then
<I>dirfd</I>
is ignored.
<P>
See
<B><A HREF="/cgi-bin/man/man2html?2+openat">openat</A></B>(2)
for an explanation of the need for
<B>mkdirat</B>().
<A NAME="lbAF">&nbsp;</A>
<H2>RETURN VALUE</H2>
<B>mkdir</B>()
and
<B>mkdirat</B>()
return zero on success, or -1 if an error occurred (in which case,
<I>errno</I>
is set appropriately).
<A NAME="lbAG">&nbsp;</A>
<H2>ERRORS</H2>
<DL COMPACT>
<DT id="4"><B>EACCES</B>
<DD>
The parent directory does not allow write permission to the process,
or one of the directories in
<I>pathname</I>
did not allow search permission.
(See also
<B><A HREF="/cgi-bin/man/man2html?7+path_resolution">path_resolution</A></B>(7).)
<DT id="5"><B>EDQUOT</B>
<DD>
The user's quota of disk blocks or inodes on the filesystem has been
exhausted.
<DT id="6"><B>EEXIST</B>
<DD>
<I>pathname</I>
already exists (not necessarily as a directory).
This includes the case where
<I>pathname</I>
is a symbolic link, dangling or not.
<DT id="7"><B>EFAULT</B>
<DD>
<I>pathname</I> points outside your accessible address space.
<DT id="8"><B>EINVAL</B>
<DD>
The final component (&quot;basename&quot;) of the new directory's
<I>pathname</I>
is invalid
(e.g., it contains characters not permitted by the underlying filesystem).
<DT id="9"><B>ELOOP</B>
<DD>
Too many symbolic links were encountered in resolving
<I>pathname</I>.
<DT id="10"><B>EMLINK</B>
<DD>
The number of links to the parent directory would exceed
<B>LINK_MAX</B>.
<DT id="11"><B>ENAMETOOLONG</B>
<DD>
<I>pathname</I> was too long.
<DT id="12"><B>ENOENT</B>
<DD>
A directory component in
<I>pathname</I>
does not exist or is a dangling symbolic link.
<DT id="13"><B>ENOMEM</B>
<DD>
Insufficient kernel memory was available.
<DT id="14"><B>ENOSPC</B>
<DD>
The device containing
<I>pathname</I>
has no room for the new directory.
<DT id="15"><B>ENOSPC</B>
<DD>
The new directory cannot be created because the user's disk quota is
exhausted.
<DT id="16"><B>ENOTDIR</B>
<DD>
A component used as a directory in
<I>pathname</I>
is not, in fact, a directory.
<DT id="17"><B>EPERM</B>
<DD>
The filesystem containing
<I>pathname</I>
does not support the creation of directories.
<DT id="18"><B>EROFS</B>
<DD>
<I>pathname</I>
refers to a file on a read-only filesystem.
</DL>
<P>
The following additional errors can occur for
<B>mkdirat</B>():
<DL COMPACT>
<DT id="19"><B>EBADF</B>
<DD>
<I>dirfd</I>
is not a valid file descriptor.
<DT id="20"><B>ENOTDIR</B>
<DD>
<I>pathname</I>
is relative and
<I>dirfd</I>
is a file descriptor referring to a file other than a directory.
</DL>
<A NAME="lbAH">&nbsp;</A>
<H2>VERSIONS</H2>
<B>mkdirat</B>()
was added to Linux in kernel 2.6.16;
library support was added to glibc in version 2.4.
<A NAME="lbAI">&nbsp;</A>
<H2>CONFORMING TO</H2>
<B>mkdir</B>():
SVr4, BSD, POSIX.1-2001, POSIX.1-2008.
<P>
<B>mkdirat</B>():
POSIX.1-2008.
<A NAME="lbAJ">&nbsp;</A>
<H2>NOTES</H2>
Under Linux, apart from the permission bits, the
<B>S_ISVTX</B>
<I>mode</I>
bit is also honored.
<P>
There are many infelicities in the protocol underlying NFS.
Some of these affect
<B>mkdir</B>().
<A NAME="lbAK">&nbsp;</A>
<H3>Glibc notes</H3>
On older kernels where
<B>mkdirat</B>()
is unavailable, the glibc wrapper function falls back to the use of
<B>mkdir</B>().
When
<I>pathname</I>
is a relative pathname,
glibc constructs a pathname based on the symbolic link in
<I>/proc/self/fd</I>
that corresponds to the
<I>dirfd</I>
argument.
<A NAME="lbAL">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+mkdir">mkdir</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?2+chmod">chmod</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+chown">chown</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+mknod">mknod</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+mount">mount</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+rmdir">rmdir</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+stat">stat</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+umask">umask</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+unlink">unlink</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?5+acl">acl</A></B>(5)
<B><A HREF="/cgi-bin/man/man2html?7+path_resolution">path_resolution</A></B>(7)
<A NAME="lbAM">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="21"><A HREF="#lbAB">NAME</A><DD>
<DT id="22"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="23"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DL>
<DT id="24"><A HREF="#lbAE">mkdirat()</A><DD>
</DL>
<DT id="25"><A HREF="#lbAF">RETURN VALUE</A><DD>
<DT id="26"><A HREF="#lbAG">ERRORS</A><DD>
<DT id="27"><A HREF="#lbAH">VERSIONS</A><DD>
<DT id="28"><A HREF="#lbAI">CONFORMING TO</A><DD>
<DT id="29"><A HREF="#lbAJ">NOTES</A><DD>
<DL>
<DT id="30"><A HREF="#lbAK">Glibc notes</A><DD>
</DL>
<DT id="31"><A HREF="#lbAL">SEE ALSO</A><DD>
<DT id="32"><A HREF="#lbAM">COLOPHON</A><DD>
</DL>
<HR>
This document was created by
<A HREF="/cgi-bin/man/man2html">man2html</A>,
using the manual pages.<BR>
Time: 00:05:33 GMT, March 31, 2021
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