List forms for system, exec, etc

Perl's system and exec functions can take lists instead of strings:

$filename = "a file containing spaces";

# Won't work
system "/bin/rm $filename";

# Better way
system("/bin/rm", $filename)==0 or die "rm failed";

# Exec example
exec "/opt/bin/doit @args";

# Better
exec "/opt/bin/doit", @args;
die "exec failed";