VMS has a number of features that vary with the version of VMS, and also
features that can be enabled.
Perl scripts running on VMS may need to know what features are enabled,
or to enable the features.
It appears to me that the vmsish module is the place to put these if I
can figure out how to get them all implemented.
In one at least one case, I am not sure how to name the function and
implement them.
Currently there are two "exit" modes, VMS mode, and a default mode that
returns either a success SS$_NORMAL, or SS$_ABORT for a failure.
Another "exit" mode is needed that encodes the UNIX like status into a
VMS status code in the way that the GNV Bash shell and other C program
would expect it to be.
I am not sure how to specify setting that mode. If you need to pass the
exit numbers back to the DCL shell, that is the preferred mode to use,
not the use "vmsish 'exit', which needs to be maintained for
compatibility with Perl scripts that actually return real VMS status codes.
Passing numbers that are not native VMS status codes to the VMS shell
can cause havoc to any DCL scripts that contain the Perl commands as the
status codes are actually signaled to the shell, and optionally logged
in the accounting file.
So if those signals from the UNIX codes are not trapped or suppressed,
unexpected behavior can happen. And when I have been in a system
management role, I have had the unfortunate job of troubleshooting and
cleaning up the resulting mess.
Possibly it could be named: vmsish::use_posix_exit($value);
The other methods are:
vmsish::decc_feature_get_index($name);
vmsish::decc_feature_get_name($index);
vmsish::decc_feature_get_value($name, $mode);
vmsish::decc_feature_set_value($name, $mode, $value);
vmsish::decc_feature_deed_to_child($value);
The decc_feature_* methods are wrappers for the C library calls of the
same name, just exposed to make them easier for Perl scripts to use
them. Except for the decc_feature_deed_to child. All Perl scripts
would need to reference or set the C features through these methods,
because internally Perl would could cache them.
Also some decc_feature settings have side effects on other DECC features.
The decc_feature_deed_to_child would make any DECC features set after
that point visible to (inherited by) any child processes that used the C
library. For VMS prior to 7.3, the child processes will always inherit
the settings.
It is expected that in most cases further wrappers will be used in other
Perl modules to simplify the use of these settings, but by exposing the
"raw" interface here, it allows those wrappers to be written in Perl
instead of in C.
For example, a UNIX_FILENAME_REPORT method could be exposed in
File::Spec::VMS that actually just calls these vmsish methods under the
covers.
vmsish::dcl_present;
Returns if the DCL shell is present. Currently Perl probably will not
work well if it was not, but food for thought for the future.
vmsish::dcl_extended_syntax($value);
Returns/sets if the DCL shell is set to extended syntax mode. Setting
this mode through this interface will also cause interaction with the
obvious DECC features that this complements.
vmsish::dcl_command_line_length;
The length of a single line DCL command. Currently 255 bytes, future
4096 bytes on 64 bit platforms past 7.3-2.
vmsish::dcl_command_file_line_length;
The length of line in a DCL command file. Should be 1024 bytes for
traditional, but I suspect that the internal C code in Perl can only
deal with 255 bytes. With 64 bit platforms past 7.3-2 it should be 8192.
vmsish::dcl_symbol_value_length;
The size that can be stored in a DCL symbol, should be 1024 bytes for
VAX and 64 bit VMS before 7.3-2, and 8192 otherwise, but again, the
internal C code in Perl probably is limited to 255 characters.
vmsish::dcl_token_length;
This is currently limited to 255 bytes.
vmsish::logical_name_value_length;
This is currently limited to 255 bytes.
vmsish::vms_pathname_length;
The maximum length of a pathname including device name and directory
names and version number in string form. Currently limited internally
in Perl to 255 bytes. Future is 4095 bytes. This includes "quoting"
characters. Internal storage after the quoting is resolved is limited
to 1024 bytes.
vmsish::unix_pathname_length;
The maximum length of a UNIX pathname from "/". In a UNIX pathname, the
quoting characters are not present on the external representation so it
is limited to 1024 characters.
vmsish::vms_filename_length;
The length of an 8 bit character set file name and extension with out
the directory or device component and including the version string.
Perl currently reserves 255 characters for this, and that is unchanged.
On ODS-2 file systems, only about 86 characters can really be used.
On ODS-5 systems, 253 characters can be used.
vmsish::wide_filename_length;
The length of a UCS-2 encoded filename. Currently 116 16 bit
characters. I really do not know what Perl would do with one of these,
but since I was looking up the limits, it seemed some thing to add.
-John
[EMAIL PROTECTED]
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