topic Re: Using hint values from rms to get filesize in Operating System - OpenVMS

Using hint values from rms to get filesize

Tom Gates — Tue, 08 Feb 2011 19:22:31 GMT

Hi all,

I was wondering, how do i use the hint values provided by VMS for FIX and VFC files.
The data part is said to be with out any extra paddings ...
So how can we get the file size?
record_count + data_count or as every record is terminated with CRLF, shouldn't it be appropriate to use (2*record_count + data_count) for getting file size ... but then will it hold good for all the cases?

Re: Using hint values from rms to get filesize

Steven Schweda — Tue, 08 Feb 2011 20:15:28 GMT

> [...] the hint values [...]

The what?

> [...] said to be [...]

Who says what, exactly?

> So how can we get the file size?

Define "file size". VMS normally keeps track
of the disk space occupied by a file, but
whether that can be translated into a useful
byte count can depend on what's in the file.

To see what's really in a file:

HELP DUMP

Don't expect to see actual CR or LF
characters in a non-stream record format
file.

Is there some actual problem which you are
trying to solve?

Re: Using hint values from rms to get filesize

John Gillings — Tue, 08 Feb 2011 21:24:13 GMT

Tom,

Depends on what you mean by "filesize"

From DCL, F$FILE_ATTRIBUTES ALQ will give you the allocated disk space, some of which will probably be unused.

> (2*record_count + data_count) for getting
>file size ... but then will it hold good
>for all the cases?

No. Metadata size depends on the record format, and record lengths as odd lengths are padded.

For sequential files, EOF and FFB can be used to find the space in use (including both data and metadata).

If positive, FILE_LENGTH_HINT should be accurate to give you the data size, but if it's negative (invalid) you'll need to count.

Re: Using hint values from rms to get filesize

GuentherF — Wed, 09 Feb 2011 00:34:26 GMT

Like this?

$ filesize = F$FILE_ATTRIBUTES("LOGIN.COM","EOF") * 512 + F$FILE_ATTRIBUTES("LOGIN.COM","FFB") - 1
$ SHOW SYMBOL filesize
FILESIZE = 2019 Hex = 000007E3

This gives you the used space of a file with file organization = SEQ (=sequential).

You didn't tell which file organization nor did you tell whether this is needed in a program or a command procedure. And then you didn't tell what you need that number for at all.

I would give you 3 lemons for a poorly asked question. ;-)

/Guenther