comments

main.go

@@ -11,11 +11,21 @@ import (
 )
 
 var (
-	input         = flag.String("i", "^.*?$", "input pattern")
-	output        = flag.String("o", "{0}", "output pattern")
+	// regex with sub groups
+	input = flag.String("i", "^.*?$", "input pattern")
+
+	// format string with {0} as placeholders
+	// {0} always matches the whole line
+	// {1} and onwards match their respective sub groups
+	// You can optionall specify a printf-syntax for formatting like this: {1:%s} or {1:%02d}
+	// printf-syntax is currently supported for: strings, floats, integers
+	output = flag.String("o", "{0}", "output pattern")
+
+	// don't ignore lines which do not match against input.
+	// they will be copied without any changes
 	keepUnmatched = flag.Bool("k", false, "keep unmatched lines")
 
-	replacePattern = regexp.MustCompile("\\{(\\d+)(?::(.*?))?\\}")
+	replacePattern = regexp.MustCompile(`\{(\d+)(?::(.*?))?\}`)
 )
 
 func main() {