4.2BSD/usr/man/man2/mkdir.2

.TH MKDIR 2 "27 July 1983"
.UC 4
.SH NAME
mkdir \- make a directory file
.SH SYNOPSIS
.nf
.ft B
mkdir(path, mode)
char *path;
int mode;
.fi
.ft R
.SH DESCRIPTION
.I Mkdir
creates a new directory file with name
.IR path .
The mode of the new file
is initialized from
.IR mode .
(The protection part of the mode
is modified by the process's mode mask; see
.IR umask (2)).
.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.
.PP
The low-order 9 bits of mode are modified by the process's
file mode creation mask: all bits set in the process's file mode
creation mask are cleared.  See
.IR umask (2).
.SH "RETURN VALUE
A 0 return value indicates success.  A \-1 return value
indicates an error, and an error code is stored in
.I errno.
.SH "ERRORS
.I Mkdir
will fail and no directory will be created if:
.TP 15
[EPERM]
The process's effective user ID is not super-user.
.TP 15
[EPERM]
The \fIpath\fP argument contains a byte with the high-order bit set.
.TP 15
[ENOTDIR]
A component of the path prefix is not a directory.
.TP 15
[ENOENT]
A component of the path prefix does not exist.
.TP 15
[EROFS]
The named file resides on a read-only file system.
.TP 15
[EEXIST]
The named file exists.
.TP 15
[EFAULT]
.I Path
points outside the process's allocated address space.
.TP 15
[ELOOP]
Too many symbolic links were encountered in translating the pathname.
.TP 15
[EIO]
An I/O error occured while writing to the file system.
.SH "SEE ALSO"
chmod(2), stat(2), umask(2)