How do you determine if a directory is empty or not?

[Kenneth Toler]

I am using a DCL COM file.

Is there a way to determine if files exist in a dirctory and return a "TRUE" or "FALSE" string?

If not, how can this be accomplished?

[Robert Gezelter]

Kenneth,

Use the lexical function F$SEARCH("[directory]*.*") to locate any file in the directory. If it comes back with an empty string ("") then there were no files in the directory.

- Bob Gezelter, http://www.rlgsc.com

[Kenneth Toler]

Can you show me an example of how to use an IF statement with the F$SEARCH so that if there is a NULL string then it will execute a list of commands and if it is NOT a NULL string then it will execute another list of commands?

[Robert Gezelter · Accepted solution]

Kenneth,

$ IF F$SEARCH("[sssss]*.*) .EQS. ""
$ THEN
$ ...
$ ENDIF

There are also equivalent ways to express the IF using the F$LENGTH lexical function wrapping the F$SEARCH.

- Bob Gezelter, http://www.rlgsc.com

[Kenneth Toler]

What do you mean by "equivalent ways to express the IF using the F$LENGTH lexical function wrapping the F$SEARCH"? Could you give an example?.

[Robert Gezelter]

Kenneth,

$ IF F$LENGTH(F$SEARCH(...)) .EQ. 0
$ THEN
$ ...
$ ENDIF

- Bob Gezelter, http://www.rlgs.com

[Wim Van den Wyngaert]

If you execute the f$sea in a loop (e.g. every 5 minutes), you must initialize the f$sea context before each f$sea.
E.g.
x=f$sea("qqqqqq.qqqqqq")
x=f$sea("dir:*.*")
if x .eqs. "" ...

If not, f$sea will return each file of the directory (1 in each loop), then a blank ("") and then restart returning the files.

Wim

[Antoniov.]

Kenneth,
if you like boolean value this is your example:
$ flag_empty=f$search("dir:*.*").eqs.""
$ if flag_empty
$ then
$ ... Directory empty
$ endif
$ ...

Antonio Vigliotti

[John Gillings]

As some have pointed out here, there's a potential problem with search context. To make your code more robust, prevent it from interfering with other searches, and prevent resource leaks, it's best to use an unique search ID context for the search, and clear context both before and after use. Here's an example:

$ check_dir="disk:[mydir]"

$ search_context=='search_context'+1
$ ctx=search_context
$ tmp=F$SEARCH("clear",ctx) ! Clear to start
$ dir_empty=F$SEARCH("''check_dir'*.*",ctx).EQS.""
$ IF dir_empty
$ THEN
$ ! directory is empty
$ ELSE
$ tmp=F$SEARCH("clear",ctx) ! Clear at end
$ ENDIF

The global symbol "search_context" is used to generate a stream-id for the search. This code can safely execute within another F$SEARCH loop.

[Hein van den Heuvel]

Ken wrote

"Is there a way to determine if files exist in a dirctory..."

yes, many

"... and return a "TRUE" or "FALSE" string?"

Yes, but returning a those strings is a little bit strange request. Most applications would look for a symbol set to true or false or (or perhaps 1 and 0 )

Anyway, just to give a completely different solution:

$directory = "XXX.DIR.1"
$string = "TRUE"
$open/read/share=write dir 'directory
$read/end=empty
$string = "FALSE"
$empty:
$close dir
$write sys$output "It is ", string, "that directory ", directory, " is empty.

grins,
Hein.

$write