Regular Expression

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THere are three dialects of regular expressions: BRE- basic regular expression ERE -Extended regular expression PCRE - Perl - compatible regular expression

You can do things like search for things that are formatted like and address or phone number.

It's not so great for HTML - it can't find things that are nested too far down. This is an acknowledged way down. If you need to do web-pages think about using something like Beautiful Soup.

grep is a common tool for finding basic regular expressions. egrep is for extended regular expressions.

BRE's a parenthesis is just a parenthis.

egreps allows you to look for things like 'r......t$' and you will be able to find everything that is eight letters long that starts with r and ends with t.

. is a wildcard ^ is the beginning of the line only [ ] brackets is for character class (any character in the list).

If you want to find any word that has the same character class of slugfest.

boxes = [aceimnorsuvwyx]

Searching for words in a british word a question mark means that the character in front of it is optional. 'colu?r'

'organis?z?e' does'nt work

'organi[sz]e' will pull both spellings

{ } allows a number

o{2} means words where oo occurs

what is a word that has three reference - that has back reference. {2,4} means that it occurs between 2 and 4 times.

[- ]? means it will find a hyphen or a space

[0-9] is the same as [0123456789]

[0-9]{16} will find 16 chsracters in a row.

egrep -q 'Aspiration'

Symbol times ? 0.1 {4} 4 + 1 or more

  • 0 or more