Chances are that the server provides different environment variables, and that perl can't be found.

Thanks for you reply,
Again everything works running perl in cgi-bin directory, but when I run it through the browser everything is fine except calling perl inside.

When I use system() it says "cmd in not found in the path..." which is the path to cgi-bin dir where the scripts are..??
With backtiks call it ia just ignored, so
@arr = `perl -w xxx "print results to STDOUT"`
returns an empty @arr.

Can you explain in more details what the problem is?

Any log messages? As i see you are calling perl interpreter directly? Did you try to write full path to perl?

With ` ` I do not have any failures in log.
I run:

my @arr = `perl -w $solver_file "$inp_file" "$outfile"`;
[download]

$outfile is just an indication to print to STDOUT
I have Cygwin and ActivePerl on my machine which starts all pathes with /cygdrive/c/.
when I type "which perl" in DOS cmd I get
/cygdrive/c/ActivePerl/bin/perl
So I tried

my @arr = `/cygdrive/c/ActivePerl/bin/perl -w $solver_file "$inp_file"
+ "$outfile"`;
[download]

instead but same result, @arr is empty.

You may need to make the path-to-perl more windows-like.

Try

my @arr = `C:\\ActivePerl\\bin\\perl -w $solver_file "$inp_file" "$out
+file"`;
[download]

I suspect the Windows cmd shell may not understand "/cygdrive", or may default to a different Windows drive letter.

     "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom