Progress Bar Between Multiple System Calls

[monkfan]

Dear all,
AFAIK, progress bar can only be applied under loops. For example we can use Term::ProgressBar or Smart::Comments. But is there away to do it for system call like this:

#!/usr/bin/perl

system("code1.out param1 > output.txt");
system("code2.out param2 output.txt > output_final.txt");

How can I show Progress Bar between first (code1) system call and the second (code2) system call? Especially we don't know how long each system call will take.

Preferrably not using external CPAN module (except pre-installed module).