According to the documentation for exec:

The "exec" function executes a system command and never returns -- use "system" instead of "exec" if you want it to return.

So, system should run each simple command serially, and wait for each to finish. For example:

use warnings;
use strict;

system 'sleep 5'                and die "ERROR: sleep died\n";
system 'echo hello > foo.txt'   and die "ERROR: echo died\n";
system 'cat foo.txt'            and die "ERROR: cat died\n";
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On my linux system, "sleep" executes, then "echo" then "cat".