Setting VMS logicals from Quick

[Rich `Lego-Man' Jesse - 7633]

Martyn Thomson posted:

MT> Does anyone have experience of repeatedly setting a VMS logical using the
MT> RUN COMMAND verb?
MT> Here's the scenario - 
...
MT>   LET T_COMMAND = &
MT>    "DEFINE/JOB TAB$SUBJ$AREA TSQ$DISK8:[DATA_1999]TAB_SUBJ_AREA.DAT"
MT>   RUN COMMAND T_COMMAND
MT> 
MT> Then test if the file exists, if not use the previous year's data  - 
MT> 
MT>   LET T_COMMAND = '$ IF F$SEARCH(""TAB$SUBJ$AREA"") .EQS. """" THEN ' + &
MT>    "DEFINE/JOB TAB$SUBJ$AREA TSQ$DISK8:[DATA_1998"]TAB_SUBJ_AREA.DAT"
MT>   RUN COMMAND T_COMMAND
MT> 
MT> If the file exists in 1999 there's no problem, it works fine and the file is
MT> accessed, but if it's in 1998 the logical isn't replaced!

I assume that the extraneous quote (") next to DATA_1998 in your second
DEFINE/JOB is a typo, right?

Having been a VMSer for 12 years now, I'm not sure why you have the quotes
doubled up in the F$SEARCH lexical function.  The only reason to duplicate a
quote is when you want a quote in a literal.  For example:

        $MY_SYMBOL = "Rich "Lego-man" Jesse"

... is improper syntax.

        $MY_SYMBOL = "Rich ""Lego-man"" Jesse"
	$SHOW SYMBOL MY_SYMBOL
	  MY_SYMBOL = "Rich "Lego-man" Jesse"

... is the correct way of specifying a quote character within a quoted literal.

Now, your doubled-up quotes in F$SEARCH(""TAB$SUBJ$AREA"") will still work
(although I can't give you the exact reason why).  But the lexical will never
return a quote, which is what """" is equal to.  Remember, DCL will interpret
"""" as a literal specifying one quote character.  So, the IF will *always* be
false, and the second DEFINE/JOB can *never* be executed.

One last thing I'm not sure about is if QUICK requires the extra quotes for the
RUN COMMAND command, but I'm fairly certain it doesn't.  For a fix, try:

        LET T_COMMAND = '$ IF F$SEARCH("TAB$SUBJ$AREA") .EQS. "" THEN ' + &
        "DEFINE/JOB TAB$SUBJ$AREA TSQ$DISK8:[DATA_1998]TAB_SUBJ_AREA.DAT"
        RUN COMMAND T_COMMAND

Hope this helps!  Let me know how/if it works!  :)

Rich Jesse                              Programmer/Analyst
rjesse@qtiworld.com                     Quad/Tech International, Sussex, WI USA
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