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moves a link

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waldek 2021-07-06 23:04:04 +02:00
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modules/qualifying/learning_regex.md
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@ -94,7 +94,7 @@ Let's break it down a bit:
* `.*` matches almost any character as many times as we want * `.*` matches almost any character as many times as we want
In the above pattern you see *two* different forms of character classes, the `[A-Z]` and the `[[:alnum:]]`. In the above pattern you see *two* different forms of character classes, the `[A-Z]` and the `[[:alnum:]]`.
Worth noting is that you can negate an expansion by putting a `^` inside it as such `grep '^[^A-Z].*' regex_03.txt` (not I used the first list because the animals list has no words starting with a capital letter). Worth noting is that you can negate an expansion by putting a `^` inside it as such `grep '^[^A-Z].*' regex_03.txt` (note I used the first list because the animals list has no words starting with a capital letter).
This is basically the same as `grep '^[a-z].*' regex_03.txt`. This is basically the same as `grep '^[a-z].*' regex_03.txt`.
### The backslash character and special expressions ### The backslash character and special expressions
@ -114,12 +114,23 @@ let's break this one down.
## Beyond basic ## Beyond basic
TODO The tests done above are a quick introduction to what regex are and how to read them.
To master them there are only two things you need to do.
1. use them
2. google
There is just no other way to wrap your head around it.
You should see it as a puzzle you're trying to solve.
To get you started I urge you to go to [this](http://regextutorials.com/) website and start the **introduction to regex** section.
It highlights automatically what your pattern is doing.
Once you completed the introduction you should try their exercises and the ones I made for you below.
## Exercises ## Exercises
Below are some practical exercises and files to go with them. Below are some practical exercises and files to go with them.
Use them to test out you grepping skills and as inspiration for personal challenges. Use them to test out you grepping skills and as inspiration for personal challenges.
I've tested all of the challenges myself but there are a lot of different ways to get the same result with a different regex.
* configuration [file](./assets/sysctl.conf) * configuration [file](./assets/sysctl.conf)
* print only lines with actual configuration settings (ignore comments and empty lines) * print only lines with actual configuration settings (ignore comments and empty lines)
@ -140,6 +151,3 @@ Use them to test out you grepping skills and as inspiration for personal challen
* extract all web links * extract all web links
* only the base link (https://www.example.co.uk) * only the base link (https://www.example.co.uk)
* both http and https links * both http and https links
There are some very good regex exercises online as well.
[This](http://regextutorials.com/) is a good starting point.