regex

• special chars

• cheatsheet

  • get URL

  • matches if exits

  • not matche a word

  • not matches multiple keywords

references:

• Regular expression syntax cheat sheet

• Regular Expressions Reference Table of Contents

special chars

CHARACTER	COMMENTS
?:	non capturing group
?=	positive look ahead
?!	negative look ahead
?<=	positive look behind
?<!	negative look behind

cheatsheet

[!NOTE|label:references:]

• cheat-sheet for password crackers

get URL

$ echo http://www.baidu.com | awk '{for(i=1;i<=NF;i++){if($i~/^(http|ftp):\/\//)print $i}}'
http://www.baidu.com

# or: https://www.commandlinefu.com/commands/view/4174/match-a-url
$ egrep 'https?://([[:alpha:]]([-[:alnum:]]+[[:alnum:]])*\.)+[[:alpha:]]{2,3}(:\d+)?(/([-\w/_\.]*(\?\S+)?)?)?'

matches if exits

[!NOTE|label:samples:]

✔️   keyword.baz.com
✔️   string-keyword.baz.com
✔️   keyword-staging.bar.com
✔️   keyword-staging.foo.com

^.*keyword(?:-staging)?\.[^\]+\.com

not matche a word

[!NOTE|label:samples:]

❌ /etc/kubernetes/config.backup/config.backup.20220303/admin.conf
✔️  /etc/kubernetes/pki/admin.conf

^((?!backup).)+(admin|kubelet)\.conf$

not matches multiple keywords

[!NOTE|label:samples:]

❌ foo-jenkins.domain.com
❌ foo-jenkins.domain.com/Monitor/
❌ marslo.github.com
❌ 127.0.0.1

 ^((?!.*\-jenkins\.[^\.]+\.com|.*Monitor/$|.*detail.*pipeline|.*api|marslo.github.*|shields.io|127.0.0.1|0.0.0.0|localhost).)*$