The real problem with setuid scripts on Unix isnot that writing secure shell scripts is challenging and obscure, itis that they are fundamentally insecure because of how the kernel runsthem. While the kernel runs programs by directly loading them intomemory , it runs scripts by running thescript's interpreter with the filename of the script, leaving it up tothe interpreter to read and execute the script itself. As is normal onUnix, there is nothing that keeps what file the filename points tothe same between these two