man-pages/man2/mkdir.2

.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
.\"                               1993 Michael Haardt
.\"                               1993,1994 Ian Jackson.
.\" You may distribute it under the terms of the GNU General
.\" Public License. It comes with NO WARRANTY.
.\"
.TH MKDIR 2 2010-06-26 "Linux" "Linux Programmer's Manual"
.SH NAME
mkdir \- create a directory
.SH SYNOPSIS
.nf
.B #include <sys/stat.h>
.B #include <sys/types.h>
.\" .B #include <unistd.h>
.sp
.BI "int mkdir(const char *" pathname ", mode_t " mode );
.fi
.SH DESCRIPTION
.BR mkdir ()
attempts to create a directory named
.IR pathname .

The argument
.I mode
specifies the permissions to use.
It is modified by the process's
.I umask
in the usual way: the permissions of the created directory are
.RI ( 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 file system is mounted with BSD group semantics
.RI ( "mount -o bsdgroups"
or, synonymously
.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.

If the parent directory has the set-group-ID bit set then so will the
newly created directory.
.SH "RETURN VALUE"
.BR mkdir ()
returns zero on success, or \-1 if an error occurred (in which case,
.I errno
is set appropriately).
.SH ERRORS
.TP
.B EACCES
The parent directory does not allow write permission to the process,
or one of the directories in
.I pathname
did not allow search permission.
(See also
.BR path_resolution (7).)
.TP
.B EEXIST
.I pathname
already exists (not necessarily as a directory).
This includes the case where
.I pathname
is a symbolic link, dangling or not.
.TP
.B EFAULT
.IR pathname " points outside your accessible address space."
.TP
.B ELOOP
Too many symbolic links were encountered in resolving
.IR pathname .
.TP
.B EMLINK
The number of links to the parent directory would exceed
.BR LINK_MAX .
.TP
.B ENAMETOOLONG
.IR pathname " was too long."
.TP
.B ENOENT
A directory component in
.I pathname
does not exist or is a dangling symbolic link.
.TP
.B ENOMEM
Insufficient kernel memory was available.
.TP
.B ENOSPC
The device containing
.I pathname
has no room for the new directory.
.TP
.B ENOSPC
The new directory cannot be created because the user's disk quota is
exhausted.
.TP
.B ENOTDIR
A component used as a directory in
.I pathname
is not, in fact, a directory.
.TP
.B EPERM
The file system containing
.I pathname
does not support the creation of directories.
.TP
.B EROFS
.I pathname
refers to a file on a read-only file system.
.SH "CONFORMING TO"
SVr4, BSD, POSIX.1-2001.
.\" SVr4 documents additional EIO, EMULTIHOP
.SH NOTES
Under Linux apart from the permission bits, only 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).
.PP
There are many infelicities in the protocol underlying NFS.
Some of these affect
.BR mkdir ().
.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 path_resolution (7)