so do you mean to say that the "$test" program in "open(TH, "|$test >$tmpfn" )" is returning the error code?

The error comes from the child via the waitpid done by close.

It could from an error that occurred while trying to launch a shell to execute that command produced by "$test >$tmpfn". (Hopefully this isn't possible on your system.)

Otherwise, it's the error code of the launched shell. The shell will use something based on the error code of the last program it launched as its exit code.

and it is not a standard error code due to some problem with call that it is failing.

There is no standard for exit codes except for zero: success, non-zero: error. That's why the meaning of 60 is a guess.