kielstirling ++ is right on target, and my apologies for not explaining the [>fileOut] parameter. This designates an optional argument that's used to direct output to a file, instead of the screen. So, for example, you could do the following on the command line:

perl script.pl '/the/dir/to/scan' indexDS.txt >results.txt
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Thus, instead of printing to the screen, output's directed to a file. Omitting the last parameter will just print the results to the screen.

Thanks again, Kenosis. Yes, indeed. Entering the third option without brackets, does create a text file, but without any results(?) The files, I am looking for, however do exist in the directory. So they should be found.

Hmm.. If I get the two arrays (@ds and @dirFile) in my script listed, I can see that grep /$line/ should find the matching elements in the second array. But @results keeps beeing empty. The funny thing is: if I define @ds writing some of the wanted IDs directly into the script

 @ds = ("I C 7702", "I C 7710");

the script works perfectly. But I want the array filled by reading a long list of IDs from a text file. Any idea what is going wrong?

Hi better,

The files, I am looking for, however do exist in the directory. So they should be found.

To start with Kenosis' script should work. I tried it, using your description of the problem you posted and I have outputs, though similar filenames which were not included in the "indexDS.txt" were also printed.

Secondly, how are you using the script, maybe you have some other code over-writing the variable "@result"
Hope this helps.

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If you show me, I'll remember.
if you involve me, I'll understand.
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