Previously we looked at simple terminal commands like ls, cd. We know that ls simply outputs all files in working directory. But in practice command without options and parameters is almost useless. In more complex situations you may need to list special files, or list files from specific directory without going to it. This is why UNIX commands are run with options and parameters command [options] [parameters] There can be more than one option and parameter for single command. For instance we used a cd .. command to go to previous directory. Dots .. are nothing more than parameters. Lets see what parameters we have with ls command. ls -l it displays list of files in long format. You can see that we get much more information by ading simple option -l. Lets say we want to display files in long format from different than working directory. Then we need to type in path to directory as parameter.