use String::ShellQuote qw( shell_quote );

my $cmd = shell_quote("perl", "-i", "-0777wpe", 'print STDOUT s/foo/bar/g', 'foo_test');
my $num_subs = `$cmd`;
die("Can't execute child: $!\n" if $? == -1'
die("Child killed by signal ".( $? & 0x7F )."\n") if $? & 0x7F;
die("Child exited with error ".( $? >> 8 )."\n") if $? >> 8;