No, that doesn't entirely make sense. Maybe you could give some more detail about what else you really want to do besides that one command line? What's the ultimate goal?

If you have the windows port of the bash shell, you could conceivably try something like this -- but I really don't know whether this would work:

open SHELL, "| bash.exe" or die "can't open the shell: $!";

print SHELL "type C:/temp.ml | ocaml > C:/output.txt\n";

print SHELL "dir C:/output.txt\n";

# and so on...
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But whatever you're actually trying to accomplish, there are probably better ways to do it, by allowing your own perl script to do more of the work. For example:

open TEMP, "C:/temp.ml" or die "C:/temp.ml: $!";
open CAML, "| ocaml > C:/output.txt" or die "can't run ocaml: $!";

while (<TEMP>) { print CAML }
close CAML;

open TXT, "C:/output.txt" or die "C:/output.txt: $!";
while (<TXT>) {
    # do other stuff
}
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There are lots of ways to things like this, with minimal use of "system()".