⭐️ Regex filters

Regex replace

Filter	Description
s:X:Y	Replace first match of a regular expression X with Y. Y can reference capture groups from X using $0, $1, $2, ... Any other character than : can be also used as a delimiter.
s:X	Remove first match of a regular expression X. Equivalent to s:X:.
S:X:Y S:X	Same as s but replaces/removes all matches.

Examples:

Input	Pattern	Output
12_34	{s:\d+:x}	x_34
12_34	{S:\d+:x}	x_x
12_34	{s:(\d)(\d):$2$1}	21_34
12_34	{S:(\d)(\d):$2$1}	21_43

Regex match

Filter	Description
=E	Match of a regular expression E.

Examples:

Input	Pattern	Output
12_34	{=\d+}	12

Regex switch

Filter	Description
@:X:Y	Output Y if input matches regular expression X Output nothing when there is no match.. Y can reference capture groups from X using $0, $1, $2, ... Any other character than : can be also used as a delimiter.
@:X:Y:D	Output Y if input matches regular expression X. Output D when there is no match.
@:X1:Y1:...:Xn:Yn:D	Output Yi for first regular expression Xi that matches input. Output D when there is no match.
@:D	A switch without any Xi/Yi cases which will always output D.

Examples:

Input	Pattern	Output
(any)	{@:def}	def
12	{@:^\d+$:number}	number
1x	{@:^\d+$:number}	(empty)
12	{@:^\d+$:number:string}	number
1x	{@:^\d+$:number:string}	string
ab	{@:^[a-z]+$:lower:^[A-Z]+$:upper:mixed}	lower
AB	{@:^[a-z]+$:lower:^[A-Z]+$:upper:mixed}	upper
Ab	{@:^[a-z]+$:lower:^[A-Z]+$:upper:mixed}	mixed
a=b	{@/(.+)=(.*)/key: $1, value: $2/invalid}	key: a, value: b
ab	{@/(.+)=(.*)/key: $1, value: $2/invalid}	invalid

Global regex

Filter	Description
$0, $1, $2, ...	Capture group of a global regular expression.

• Use -e, --regex or -E, --regex-filename option to define a global regular expression.
• Option -e, --regex matches regex against each input value.
• Option -E, --regex-filename matches regex against filename component of each input value.

echo 'a/b.c' | rew -e '([a-z])' '{$1}' # Will print 'a'
echo 'a/b.c' | rew -E '([a-z])' '{$1}' # Will print 'b'