Consider:

use strict;
use warnings;
use POSIX ":sys_wait_h";

my $pid = fork ();

if ($pid == 0) {
    for (1 .. 10) {
        sleep 1;
        print 'c';
    }
} else {
    while (waitpid ($pid, WNOHANG) == 0) {
        print 'p';
        sleep 1;
    }
}

print "\nDone\n";
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Prints:

ppcpcpccpcpcpcpcpcpc
Done
p
Done
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