Search Tools

Details

Most search tools like ag and rg comply with .ignore, which is formatted same as .gitignore. Tools will ignore targets specified in .ignore

`.`
`?`
`*`
`+`
`{n}`
`{n,}`
`{,m}`
`{n,m}`
`[:upper:]`	`A B C D E F G H I J K L M N O P Q R S T U V W X Y Z`
`[:lower:]`	`a b c d e f g h i j k l m n o p q r s t u v w x y z`
`[:digit:]`	`0 1 2 3 4 5 6 7 8 9`
`[:xdigit:]`	`0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f`
`[:punct:]`	! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { ¦ } ~ (Punctuation characters)
`[:blank:]`	`space` and `tab`
`[:space:]`	`tab`, `newline`, `vertical tab`, `form feed`, `carriage return`, and `space`
`[:alpha:]`	`[:lower:]` and `[:upper:]`; same as `[A-Za-z]`
`[:alnum:]`	`[:alpha:]` and `[:digit:]`, same as `[0-9A-Za-z]`
`[:graph:]`	`[:alnum:]` and `[:punct:]` (Graphical characters)
`[:print:]`	`[:alnum:]`, `[:punct:]`, and `space`
`[:cntrl:]`	Octal codes `000` through `037`, and `177` (DEL)
`\b`	Match the empty string at the edge of a word
`\B`	Match the empty string provided it’s not at the edge of a word.
`\<`	Match the empty string at the beginning of word.
`\>`	Match the empty string at the end of word.
`\w`	A synonym for `[_[:alnum:]]`
`\W`	A synonym for `[^_[:alnum:]]`
`\s`	A synonym for `[[:space:]]`
`\S`	A synonym for `[^[:space:]]`
`(a)\1`	Matches `aa` (Back references)
`a(.)¦b\1`	will not match `ba` (Only groups participated in the match can be back-referenced)

\<, \> is specific, while \b can be placed at both ends
Meta-characters like ?, +, {, |, (, ) should be escaped with backslash
- egrep or grep -E will make these characters have meta meaning by default.

Tools like ag, rg, egrep, grep -E
Common meta characters: .^$*+?()[{\|
Because \ is a literal chracter inside character classes, ^-]\ should be escaped by clever placement
- ^: Except at the start
- ]: At the start
- -: At the start or the end of the character class