note 34273 deleted from language.operators.execution by salathe

Note Submitter: aaron dot bentley at utoronto dot ca ---- waylanator's example can be dangerous, since it doesn't prevent characters with special meaning from being emitted to the commandline. Programming errors or untrusted data could cause serious problems. At the bare minimum, remove all non-alphanumeric characters before passing a string to the shell. escapeshellarg() is also useful in *nix environments, but usually the best approach is to bypass the shell, using exec() etc.