One thing that eval does that is critical is break things apart in strings. For example if in a script you wrote lscommand="ls -F", then tried to run $lscommand, the shell would give you an amusing error that it didn't find the command ls -F. If instead you eval $lscommand, it works fine. One place I use that a lot is in a script where some args are to be passed to a command (or commands). I gather them together in variable, such as lsoptions="$lsoptions $arg" At the end of dealing with the arguments, the lsoptions might have for example, "-F -a". If I try to run ls $lsoptions ls will complain about the argument "-F -a" (and you'll get really odd incomprehensible complaints too! If instead, I do eval ls $lsoptions it does just what I wanted. Yea!

Patrick