Egrep and extended Regular

Mode: pattern

Regular:

grep: Basic Regular

Extended grep: Extending the regular

Basic Regular:

. : Any single character

[]: Within the specified range

[^]: outside the specified range

Number of Matches

*: Characters appear any time

?: Characters appear 0 or 1 times

\{m,n\}: Characters appear at least m times, at most n times

\{1,\}: Characters appear at least 1 times

. *: Matches any character of any length

Anchoring:

^: Anchoring the beginning of the line

$: Anchor Line End

\< or \b: anchoring the word head

\> or \b: Anchor word endings

\(\)

\ (\1): Refers to the contents of a 1th parenthesis

Grep

-I: Ignore case

-V: Reverse Lookup

-O: Show Only strings

--colour: Displays the color

-e: Extended Regular, Egrep

-after 10: Show matching pattern lines, and 10 rows later

-before 10: Display the matching pattern line, and the previous 10 rows

-context 10: Display matching pattern lines, and 10 rows before and after faces

Extended Regular: Egrep

Character Matching:

. : Matches any character

\. Match.

[]

[^]

Number of Matches

*: Any time before the character

? : Its front character 0 or 1 times

+: Match its preceding character at least 1 times

Grep-e ' ^[[:space:]]+ '/boot/grub/grub.conf: At least 1 whitespace characters

{M,n}: characters at least m times, up to N times

Location anchoring:

^

$

\<

\>

Group:

(),

\1

Or

A|b:a or B

C|cat:c or Cat

Egrep and extended regular