.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
.\" and Copyright (C) 1993 Michael Haardt
-.\" and Copyright (C) 1993,1994 Ian Jackson.
+.\" and Copyright (C) 1993,1994 Ian Jackson
+.\" and Copyright (C) 2006, 2014 Michael Kerrisk
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" You may distribute it under the terms of the GNU General
.\" Public License. It comes with NO WARRANTY.
.\" %%%LICENSE_END
.\"
-.TH MKDIR 2 2013-01-27 "Linux" "Linux Programmer's Manual"
+.TH MKDIR 2 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
-mkdir \- create a directory
+mkdir, mkdirat \- create a directory
.SH SYNOPSIS
.nf
.B #include <sys/stat.h>
.B #include <sys/types.h>
.\" .B #include <unistd.h>
-.sp
+.PP
.BI "int mkdir(const char *" pathname ", mode_t " mode );
+
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.B #include <sys/stat.h>
+.PP
+.BI "int mkdirat(int " dirfd ", const char *" pathname ", mode_t " mode );
.fi
+.PP
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PP
+.BR mkdirat ():
+.PD 0
+.ad l
+.RS 4
+.TP 4
+Since glibc 2.10:
+_POSIX_C_SOURCE\ >=\ 200809L
+.TP
+Before glibc 2.10:
+_ATFILE_SOURCE
+.RE
+.ad
+.PD
.SH DESCRIPTION
.BR mkdir ()
attempts to create a directory named
.IR pathname .
-
+.PP
The argument
.I mode
-specifies the permissions to use.
+specifies the mode for the new directory (see
+.BR inode (7)).
It is modified by the process's
.I umask
-in the usual way: the permissions of the created directory are
+in the usual way: in the absence of a default ACL, the mode of the
+created directory is
.RI ( mode " & ~" umask " & 0777)."
-Other mode bits of the created directory depend on the operating system.
-For Linux, see below.
-
+Whether other
+.I mode
+bits are honored for the created directory depends on the operating system.
+For Linux, see NOTES below.
+.PP
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
.IR "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.
-
+.PP
If the parent directory has the set-group-ID bit set, then so will the
newly created directory.
+.\"
+.\"
+.SS mkdirat()
+The
+.BR mkdirat ()
+system call operates in exactly the same way as
+.BR mkdir (),
+except for the differences described here.
+.PP
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR mkdir ()
+for a relative pathname).
+.PP
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR mkdir ()).
+.PP
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.PP
+See
+.BR openat (2)
+for an explanation of the need for
+.BR mkdirat ().
.SH RETURN VALUE
.BR mkdir ()
-returns zero on success, or \-1 if an error occurred (in which case,
+and
+.BR mkdirat ()
+return zero on success, or \-1 if an error occurred (in which case,
.I errno
is set appropriately).
.SH ERRORS
.B EFAULT
.IR pathname " points outside your accessible address space."
.TP
+.B EINVAL
+The final component ("basename") of the new directory's
+.I pathname
+is invalid
+(e.g., it contains characters not permitted by the underlying filesystem).
+.TP
.B ELOOP
Too many symbolic links were encountered in resolving
.IR pathname .
.B EROFS
.I pathname
refers to a file on a read-only filesystem.
+.PP
+The following additional errors can occur for
+.BR mkdirat ():
+.TP
+.B EBADF
+.I dirfd
+is not a valid file descriptor.
+.TP
+.B ENOTDIR
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH VERSIONS
+.BR mkdirat ()
+was added to Linux in kernel 2.6.16;
+library support was added to glibc in version 2.4.
.SH CONFORMING TO
-SVr4, BSD, POSIX.1-2001.
+.BR mkdir ():
+SVr4, BSD, POSIX.1-2001, POSIX.1-2008.
.\" SVr4 documents additional EIO, EMULTIHOP
+.PP
+.BR mkdirat ():
+POSIX.1-2008.
.SH NOTES
-Under Linux apart from the permission bits, only the
+Under Linux, apart from the permission bits, the
.B S_ISVTX
-mode bit is honored.
-That is, under Linux the created directory actually gets mode
-.RI ( mode " & ~" umask " & 01777)."
-See also
-.BR stat (2).
+.I mode
+bit is also honored.
.PP
There are many infelicities in the protocol underlying NFS.
Some of these affect
.BR mkdir ().
+.SS Glibc notes
+On older kernels where
+.BR mkdirat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR mkdir ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.IR /proc/self/fd
+that corresponds to the
+.IR dirfd
+argument.
.SH SEE ALSO
.BR mkdir (1),
.BR chmod (2),
.BR chown (2),
-.BR mkdirat (2),
.BR mknod (2),
.BR mount (2),
.BR rmdir (2),
.BR stat (2),
.BR umask (2),
.BR unlink (2),
+.BR acl (5)
.BR path_resolution (7)