There’s a lot more to working with files on Linux than creating, listing and updating them. After all, files can be Linux commands (i.e., binaries), scripts, images, simple text files, pointers to other files or folders. You might remember the “everything is a file” description of Unix and Linux systems.
Even sockets and named pipes are files in their own way. Sometimes only the owner can see and use files, sometimes everyone can and sometimes select individuals will also have access. Here are some of the subtleties.
Listing files on Linux is easy. You use the ls command. On the other hand, commands like ls, ls -l, ls -a and ls -ltr work very differently:
Source:: Network World – Linux