Regex in Linux

Symbols

Anchors

Symbol	Meaning
^	Start of string/line
$	End of string/line
\b	Check if between \w & \W or other way
\B	If not between \w & \W or other way

Quantifiers

Symbol	Meaning
*	0 or more times
+	1 or more times
?	0 or 1 time (optional)
{n}	Exactly n times
{n,}	At least n times
{n,m}	Between n and m times

Character Classes

Symbol	Meaning
.	Any character except newline
s	Whitespace
S	Non-whitespace
\w	Any word character [a-zA-Z0-9_]
\W	Whitespace: space, \t, \n, punctuation: .,!?-, special symbols: @#£€¥$%^&*+=/\()[]{}<>:;'"|~,
\d	Digit
\d	Non-digit

Sets / Ranges

Symbol	Meaning
[abc]	Any character in the set
[^abc]	Any character not in the set

Groups

Symbol	Meaning
(abc)	Capture group
(?:abc)	Non-capturing group

Logic Operator

Symbol	Meaning
a|b	OR (alternative)

Special Characters

Sequence	Meaning
\n	Newline
\r	Carriage return
\t	Tab
\v	Vertical tab
\f	Form feed
\0xxx	Octal escape, e.g. \012
\xhhhh	Hexadecimal escape, e.g. \x41

Escape Character

Common Escape Sequences

\.  \*  \+  \?  \{  \}  \[  \]  \|  \(  \)  \^  \$
# or (i need to escape 2x becouse my shell eats one "\")
\\.  \\*  \\+  \\?  \\{  \\}  \\[  \\]  \\|  \\(  \\)  \\^  \\$

Characters that must be escaped INSIDE [ ... ]

-  ]  \

Characters that must be escaped OUTSIDE [ ... ]

.  *  +  ?  { }  [ ]  |  ( )  ^  $ 

Characters that DO not need escaping INSIDE [ ... ]

.   *   +   ?   |   (   )   {   }   $