a good example is pulseaudio

oooops.

No worries, I just wanted to mention that :) I believe you have an awesome channel and I have learned a lot. Don't take this as nitpicking :)

I'm a local server guy, I use Ubuntu because it's nice to use with my server.

Lassigamer Three things: Idk which Version of Ubuntu u use, but with 16.04 you get prompted the root password when booting into recovery mode for a shell . Second, rm -rf / doesn't work for known reasons, you have to pass --no-preserve-root to delete / . Third, if someone has physical acess to a PC with a malicious intent, you are clearly fucked. In GRUB, the attacker could add init=/bin/bash to the Kernel cmd line, and voilà, you are booting straight into a root Shell. Or He could use a live CD / remove the HDD to add a backdoor / change the root pwd or add other privileged users, 2nd of which might be less obvious. PS: sry for my Bad spelling, i'm from Germany and only 16 y/o

Simple google search... that's all it took

Oh guter Tipp. Vllt mache ich das nicht mehr

probably, yeah. I just like to think too much about non important things

regex= regular expression. It's a way to filter strings which match a certain pattern. A pretty basic example: "^Hello [a-zA-Z]+\." matches if the String starts(^) with "Hello " followed by a character between a-z or A-Z *once or more*(+) and ends with a fullstop (the "\" removes the special meaning of ".") The program checks the String character by character if it matches the given expression and stops if it hits any character that does not match (String doesnt match pattern) or reaches the end of the expression (String matches pattern) It's basicly just a syntax to tell the program what kind of pattern you are looking for in the String. You can visit regex.com to play around with it and get all the special characters and short explainations what they do.

MrAntiKnowledge Great explanation! but I think its not enough for people to understand it clearly and completely, I might try to make a code equivalent for each regex samples, which is a lot of work. :(

Well it depends on who you want it to explain to and for what reason. Maybe you could try explaining it as kind of a advanced version of a wildcard (*.txt) since that seems to be something even techilliterate people are sometimes familiar with. If you audience is more techliterate you could use finite state automatons to explain it. Or are you more interested in the actual implementation of the "matching".

The actual implementation of matching, from quantifiers matching to lookahead captures and recursion capture, I would say the audience and tech literate programmers, they also use linux but not so much for the grep, sed and other stuff with reg expression. The reason is so that not many people interrupt me with regex questions while working. Teach a man a fish and they will eat everyday as they say.

What?