Regex matching

suggest change

pat='[^0-9]+([0-9]+)'
s='I am a string with some digits 1024'
[[ $s =~ $pat ]] # $pat must be unquoted
echo "${BASH_REMATCH[0]}"
echo "${BASH_REMATCH[1]}"

Output:

I am a string with some digits 1024
1024

Instead of assigning the regex to a variable ($pat) we could also do:

[[ $s =~ [^0-9]+([0-9]+) ]]

Explanation

The [[ $s =~ $pat ]] construct performs the regex matching
The captured groups i.e the match results are available in an array named BASH_REMATCH
The 0th index in the BASH_REMATCH array is the total match
The i’th index in the BASH_REMATCH array is the i’th captured group, where i = 1, 2, 3 …

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Pattern matching and regular expressions:

* Pattern matching and regular expressions

* Behaviour when a glob does not match anything

* Check if a string matches a regular expression

* Get captured groups from a regex match against a string

* The glob

* Case insensitive matching

* The glob

* Extended globbing

* Regex matching

* The glob

* Matching hidden files

Table Of Contents

0 Getting started

1 Using trap to react to signals and system events

2 Listing files

3 Aliasing

4 Jobs and processes

5 Redirection

6 Control structures

7 Using cat

8 Arrays

9 Functions

10 Bash Parameter Expansion

11 Sourcing

12 Find

13 Here documents and here strings

14 Quoting

15 Conditional Expressions

16 Scripting with parameters

17 History substitutions

18 Math

19 Scoping

20 Process substitution

21 Programmable completion

22 Customizing PS1

23 Brace Expansion

24 Bash Arithmetic

25 getopts smart positional-parameter parsing

26 Debugging

27 Pitfalls

28 Script shebang

29 Pattern matching and regular expressions

30 Keyboard shortcuts

31 Change shell

32 Copying with cp

33 Internal variables

34 Job control

35 Case statement

36 Word splitting

37 Read a file

38 File transfer with scp

39 Pipelines

40 Managing PATH environment variable

41 Avoiding date using printf

42 Chain of commands and operations

43 Type of shells

44 true, false and commands

45 Color script output cross-platform

46 Navigating directories

47 Using sort

48 Namespace

49 co-processes

50 Typing variables

51 Jobs at specific types

52 Associative arrays

53 Handling the system prompt

54 Creating directories

55 File execution sequence

56 The cut command

57 Bash on Windows 10

58 Cut command

59 Splitting files

60 Global and local variables

61 Design Patterns

62 CGI Scripts

63 Select keyword

64 When to use eval

65 Networking with bash

66 Parallel

67 Grep

68 Strace

69 Sleep

70 Decodi

71 Contributors