On the other hand, shell scripting is prone to costly errors. Inadvertent typing errors such as rm -rf * / (instead of the intended rm -rf */) are folklore in the Unix community; a single extra space converts the command from one that deletes all subdirectories contained in the current directory, to one which deletes everything from the file system's root directory. Similar problems can transform cp and mv into dangerous weapons, and misuse of the > redirect can delete the contents of a file. This is made more problematic by the fact that many UNIX commands differ in name by only one letter: cp, cd, dd, df, etc.
