When using regular expressions, the ^ character matches the beginning of a line. For example, ^Hello will match any line that starts with Hello. The ? character matches zero or one occurrence of the preceding character or group. For example, colou?r will match both color and colour. The * character matches zero or more occurrences of the preceding character or group. For example, ab*c will match ac, abc, abbc, abbbc, and so on. The + character matches one or more occurrences of the preceding character or group. For example, ab+c will match abc, abbc, abbbc, and so on, but not ac. The charactermatchestheendofaline.Forexample, World will match any line that ends with World. References: [LPI Exam 101 Detailed Objectives], Topic 103:
GNU and Unix Commands, Weight: 25, Objective 103.7: Use regular expressions with the standard Linux utilities, Regular Expressions