Regex , Regular Expressions in 2 mins

Posted by Adarshreddy Adelli

Saturday, September 14, 2019

Today I have been on my daily routine of checking my social media. Suddenly I fell in love with a post on Linkedin which explains popular regular expressions in a short time.  Regular expressions are easily understandable but remembering those exact ones is really a big task.
Regex is supported by almost many languages out there in the market right from bash to python etc..

Let's see 

cat matches cat ca+t matches caaaaaaaaaaaaat but not ct ca*t matches caaaaaaaaaaaaat and also ct ca{2,4}t matches caat, caaat and caaaat c(at)+ matches catatatatatat c(at|orn) matches cat and corn c[ea]t matches cat and cet c[ea]+t matches caaaat, ceeet and caaeaeaaet c[A-C0-9]t matches cAt, cBt, cCt, c8t etc. c.t matches cat, c&t, c2t (any char between c and t) c.+t matches c3%x4t (any number of any chars) c.*t matches c3%x4t and as well as ct ^ denotes start of a string, $ denotes the end ^a+cat will match aaacat in aaacat but not in bbbaaacat cat$ will match cat in aaacat but not in aaacats ^cat$ will match only and only this string i.e. cat \d is for digits, \w for alphanumeric chars, \s is white space & line breaks \D is for non-digits, \W for non-alphamueric chars and \s is for non-white space chars \t for tabs, \r for carriage return and \n for newline Using .*w vs .*?w on somethingnew@1234w .*w returns somethingnew@1234w (longest match) .*?w returns somethingnew (shortest match)

I must thank the author (Somdev Sangwan ). 

Adarshreddy Adelli Saturday, September 14, 2019 bash Linux operating systems