nice and handy, dont forget to mention that if you need to perform a file action on a file with blank spaces in the name (this is too common in the windows world and if you run samba... be ready to deal with it) you must encase the file name in quotation marks so that the shell interprets it as one entry and not multiple....

EX: chmod 770 /home/bob/"file with spaces in name" (chmod is simply the command to change permissions or mode rather)

blank spaces can trip up newbies with a vengeance!