use warnings;
use strict;
use IPC::System::Simple qw/capturex/;

print capturex( $^X, 'showcmdline.pl', 'foo\\" bar\\\\', 'open(my $x,">&STDOUT");' );

__END__

"C:\Strawberry\perl\bin\perl.exe" "showcmdline.pl" "foo\\\" bar\\\\" "open(my $x,\">&STDOUT\");"
(
  "showcmdline.pl",
  "foo\\\" bar\\\\",
  "open(my \$x,\">&STDOUT\");",
)