system 'cmd.exe /c notepad.exe' || die 'no notepad';
# is the same as
system( 'cmd.exe /c notepad.exe' || die 'no notepad' );
# but you want
system( 'cmd.exe /c notepad.exe' ) && die 'no notepad';
# or you could do
system 'cmd.exe /c notepad.exe' and die 'no notepad';