Regex’s some hate some love, but in the end, we all need something productive in our life. Some people hate because the mini-language can be arcane. Others love it because it adds superpowers for text processing. Learning the arcane secrets of regex can be a rough experience, but it doesn’t have to.

so let do some exercises on regex like emails and IP for your everyday technical needs

Finding Mailing data

extract email adresses from some file

([[:alnum:]_.-]+@[[:alnum:]_.-]+?\.[[:alpha:].]{2,6})

  1. [:alnum:]: Alphanumeric characters: [:alpha:] and [:digit:]; in the C locale and ASCII character encoding, this is the same as [0-9A-Za-z].

  2. [ _.+]: One of the characters in the brackets. in which looks for one of these characters _.+

  3. ?: Makes quantifiers “lazy”

  4. \.: Escapes a special character for the .

Check for IP address

Look for IPv4 address in files

([0-9]{1,3}\.){3}[0-9]{1,3}

  1. [0-9]: One of the characters in the range from 0 to 9

  2. {1,3}: One to three times, “greedy”

  3. \.: Escapes a special character for the .

Like any programming language, it just requires a bit of understanding to get the hang of it. Regex is very powerful can be used for varies of a task that is needed. so keep in mind sprinkle of regex can improve on any project you are working on the shell