Computer hacking is almost always depicted unrealistically in fiction. Because the reality is dull and undramatic.
But here's a thing: If you're trying to access a computer system which is completely unfamiliar to you - it uses an operating system you've never seen before, a file system totally unlike any you've ever used, permissions and commands utterly foreign to you - you're basically going to have zero chance of getting anywhere at all with it. (Corollary: If you want to make a system secure, write your own operating system.)
This is where the other side of hacking comes in: social engineering. For any decent system it's much easier to obtain information by dealing with the people who work with that information, or by physical intrusion into a facility, than to try to break into the system itself via a computer network. Which is actually cool, because it makes for more interesting roleplaying adventure. So there's a good reason to be "more realistic" about computer hacking and basically disallow anything but the most simplistic hacking tricks.
Lando: We need to get through this door. It's locked too!
R2-D2: Quick, I'll hack the door!
[SFX]: < bekuku doop bleep boodit-ting-pow >
R2-D2: It's a Unix system! I know this!
[SFX]: < biwhree-foo doop deep >
PA System: In your heart, you know I'm light.
Leia: I hope you know what you're doing...
R2-D2: Yeah, me too.
[SFX]: < whir doop ewhree >
PA System: A tip-yip in every pot.
Chewbacca: Ugh. What's with all these tedious slogans?
PA System: It's the economy, stupid.
Chewbacca: I don't like it.
Leia: Please explain?