Ls

Equivalent to Windows' dir. Somebody should write a short article demonstrating its use and the more commonly used flags, and also a very brief treatise on how to use it with grep to good effect.

Most common flags:

-a -- lists all files, including hidden files
-l -- gives long listing, including permissions, owner, group and size

ls can (and is) used in conjunction with grep by using a pipe to send ls output -- which can easily fill your screen with enough entries to make you cross-eyed -- to more easily find what you're looking for. To give an example, let's say you're looking for a file that begins with name in your /etc directory. Doing an ls /etc gives you far too many entries and la -l the same thing but scrolling past you even faster. You could do a

ls | more

and look for all files that begin with name. But why waste your time going over each entry?

ls -la | grep name

will give you a long list of all files that have name in them.