Creates a directory.
Format
#include <stat.h>
int mkdir (const char *dir_spec, mode_t mode); (ISO POSIX-1)
int mkdir (const char *dir_spec, mode_t mode, . . . );
(DEC C Extension)
1 – Arguments
dir_spec
A valid OpenVMS or UNIX style directory specification that may
contain a device name. For example:
DBA0:[BAY.WINDOWS] /* OpenVMS */
/dba0/bay/windows /* UNIX style */
This specification cannot contain a node name, filename, file
extension, file version, or a wildcard character. The same
restriction applies to the UNIX style directory specifications.
mode
A file protection. See the chmod function in this section for
information about the specific file protections.
The file protection of the new directory is derived from the
mode argument, the process's file protection mask (see the umask
function), and the parent-directory default protections.
In a manner consistent with the OpenVMS behavior for creating
directories, mkdir never applies delete access to the directory.
An application that needs to set delete access should use an
explicit call to chmod to set write permission.
See the Description section of this function for more information
about how the file protection is set for the newly created
directory.
. . .
Represents the following optional arguments. These arguments have
fixed position in the argument list, and cannot be arbitrarily
placed.
unsigned int uic
The user identification code (UIC) that identifies the
owner of the created directory. If this argument is 0, the
C RTL gives the created directory the UIC of the parent
directory. If this argument is not specified, the C RTL
gives the created directory your UIC. This optional argument
is specific to the C RTL and is not portable.
unsigned short max_versions
The maximum number of file versions to be retained in the
created directory. The system automatically purges the
directory keeping, at most, max_versions number of every file.
If this argument is 0, the C RTL does not place a limit
on the maximum number of file versions.
If this argument is not specified, the C RTL gives
the created directory the default version limit of the parent
directory.
This optional argument is specific to the C RTL and is
not portable.
unsigned short r_v_number
The volume (device) on which to place the created directory
if the device is part of a volume set. If this argument is
not specified, the C RTL arbitrarily places the created
directory within the volume set. This optional argument is
specific to the C RTL and is not portable.
2 – Description
If dir_spec specifies a path that includes directories, which
do not exist, intermediate directories are also created.
This differs from the behavior of the UNIX system where these
intermediate directories must exist and will not be created.
If you do not specify any optional arguments, the C RTL
gives the directory your UIC and the default version limit of the
parent directory, and arbitrarily places the directory within the
volume set. You cannot get the default behavior for the uic or
max_versions arguments if you specify any arguments after them.
NOTE
The way to create files with OpenVMS RMS default protections
using the UNIX system-call functions umask, mkdir, creat,
and open is to call mkdir, creat, and open with a file-
protection mode argument of 0777 in a program that never
specifically calls umask. These default protections include
correctly establishing protections based on ACLs, previous
versions of files, and so on.
In programs that do vfork/exec calls, the new process image
inherits whether umask has ever been called or not from
the calling process image. The umask setting and whether
the umask function has ever been called are both inherited
attributes.
The file protection supplied by the mode argument is modified by
the process's file protection mask in such a way that the file
protection for the new directory is set to the bitwise AND of the
mode argument and the complement of the file protection mask.
Default file protections are supplied to the new directory
from the parent-directory such that if a protection value bit
in the new directory is zero, then the value of this bit is
inherited from the parent directory. However, bits in the parent
directory's file protection that indicate delete access do not
cause corresponding bits to be set in the new directory's file
protection.
3 – Return Values
0 Indicates success.
-1 Indicates failure.
4 – Examples
1.umask (0002); /* turn world write access off */
mkdir ("sys$disk:[.parentdir.childdir]", 0222);
/* turn write access on */
Parent directory file protection: System:RWD, Owner:RWD,
Group:R, World:R
The file protection derived from the combination of the mode
argument and the file protection mask set by umask is (0222)
& ~(0002), which is 0220. When the parent directory defaults
are applied to this protection, the protection for the new
directory becomes:
File protection: System:RWD, Owner:RWD, Group:RWD, World:R
2.umask (0000);
mkdir ("sys$disk:[.parentdir.childdir]", 0444);
/* turn read access on */
Parent directory file protection: System:RWD, Owner:RWD,
Group:RWD, World:RWD
The file protection derived from the combination of the mode
argument and the file protection mask set by umask is (0444)
& ~(0000), which is 0444. When the parent directory defaults
are applied to this protection, the protection for the new
directory is:
File protection: System:RW, Owner:RW, Group:RW, World:RW
Note that delete access is not inherited.