.\"	$NetBSD: mkdir.2,v 1.32 2020/02/05 08:14:36 wiz Exp $
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.\"     @(#)mkdir.2	8.2 (Berkeley) 12/11/93
.\"
.Dd February 4, 2020
.Dt MKDIR 2
.Os
.Sh NAME
.Nm mkdir ,
.Nm mkdirat
.Nd make a directory file
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/stat.h
.Ft int
.Fn mkdir "const char *path" "mode_t mode"
.In sys/stat.h
.In fcntl.h
.Ft int
.Fn mkdirat "int fd" "const char *path" "mode_t mode"
.Sh DESCRIPTION
The directory
.Fa path
is created with the access permissions specified by
.Fa mode
and restricted by the
.Xr umask 2
of the calling process.
On
.Nx
all other mode bits
.Dv ( S_ISUID ,
.Dv S_ISGID ,
.Dv S_ISTXT )
are ignored.
This is implementation defined; for example on Linux
.Dv S_ISTXT
is honored.
.Pp
.Fn mkdirat
works the same way as
.Fn mkdir
except if
.Fa path
is relative.
In that case, it is looked up from a directory whose file
descriptor was passed as
.Fa fd .
Search permission is required this directory.
.\"    (These alternatives await a decision about the semantics of O_SEARCH)
.\" Search permission is required on this directory
.\" except if
.\" .Fa fd
.\" was opened with the
.\" .Dv O_SEARCH
.\" flag.
.\"    - or -
.\" This file descriptor must have been opened with the
.\" .Dv O_SEARCH
.\" flag.
.Fa fd
can be set to
.Dv AT_FDCWD
in order to specify the current directory.
.Pp
The directory's owner ID is set to the process's effective user ID.
The directory's group ID is set to that of the parent directory in
which it is created.
.Sh RETURN VALUES
.Rv -std mkdir mkdirat
.Sh ERRORS
Both
.Fn mkdir
and
.Fn mkdirat
will fail and no directory will be created if:
.Bl -tag -width Er
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er EDQUOT
The new directory cannot be created because the user's
quota of disk blocks on the file system that will
contain the directory has been exhausted.
Or, the user's quota of inodes on the file system on
which the directory is being created has been exhausted.
.It Bq Er EEXIST
The named file exists.
.It Bq Er EFAULT
.Fa path
points outside the process's allocated address space.
.It Bq Er EIO
An I/O error occurred while making the directory entry or allocating the inode;
or an I/O error occurred while reading from or writing to the file system.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Brq Dv NAME_MAX
characters, or an entire path name exceeded
.Brq Dv PATH_MAX
characters.
.It Bq Er ENOENT
A component of the path prefix does not exist.
.It Bq Er ENOSPC
The new directory cannot be created because there is no space left
on the file system that will contain the directory.
Or, there are no free inodes on the file system on which the
directory is being created.
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er EROFS
The named file resides on a read-only file system.
.El
.Pp
In addition,
.Fn mkdirat
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa path
does not specify an absolute path and
.Fa fd
is neither
.Dv AT_FDCWD
nor a valid file descriptor open for reading or searching.
.It Bq Er ENOTDIR
.Fa path
is not an absolute path and
.Fa fd
is a file descriptor associated with a non-directory file.
.El
.Sh SEE ALSO
.Xr chmod 2 ,
.Xr stat 2 ,
.Xr umask 2
.Sh STANDARDS
The
.Fn mkdir
function conforms to
.St -p1003.1-90 .
.Fn mkdirat
conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn mkdir
function appeared in
.At v1 .