Construct a new sandbox suitable for $os, setting
flags for platform features that help. $realOS distinguishes
Perl variants on platforms such as Windows.
Untaints $string without any checks (dangerous). If $string is
undefined, return undef.
The intent is to use this routine to be able to find all untainting
places using grep.
STATIC Errors out if $string contains filtered characters.
The returned string is not tainted, but it may contain shell
metacharacters and even control characters.
Invokes the program described by $template
and @params, and returns the output of the program and an exit code.
STDOUT is returned. STDERR is THROWN AWAY.
The caller has to ensure that the invoked program does not react in a
harmful way to the passed arguments. sysCommand merely
ensures that the shell does not interpret any of the passed arguments.