Table of Contents

1. Introduction and preliminaries

1.1 Introduction to m4
1.2 Historical references
1.3 Invoking m4
1.4 Problems and bugs
1.5 Using this manual

2. Lexical and syntactic conventions

2.1 Names
2.2 Quoted strings
2.3 Other tokens
2.4 Comments

3. How to invoke macros

3.1 Macro invocation
3.2 Preventing macro invocation
3.3 Macro arguments
3.4 Quoting macro arguments
3.5 Macro expansion

4. How to define new macros

4.1 Defining a macro
4.2 Arguments to macros
4.3 Special arguments to macros
4.4 Deleting a macro
4.5 Renaming macros
4.6 Temporarily redefining macros
4.7 Indirect call of macros
4.8 Indirect call of builtins

5. Conditionals, loops and recursion

5.1 Testing macro definitions
5.2 Comparing strings
5.3 Loops and recursion

6. How to debug macros and input

6.1 Displaying macro definitions
6.2 Tracing macro calls
6.3 Controlling debugging output
6.4 Saving debugging output

7. Input control

7.1 Deleting whitespace in input
7.2 Changing the quote characters
7.3 Changing comment delimiters
7.4 Changing the lexical structure of words
7.5 Saving input

8. File inclusion

8.1 Including named files
8.2 Searching for include files

9. Diverting and undiverting output

9.1 Diverting output
9.2 Undiverting output
9.3 Diversion numbers
9.4 Discarding diverted text

10. Macros for text handling

10.1 Calculating length of strings
10.2 Searching for substrings
10.3 Searching for regular expressions
10.4 Extracting substrings
10.5 Translating characters
10.6 Substituting text by regular expression
10.7 Formatted output

11. Macros for doing arithmetic

11.1 Decrement and increment operators
11.2 Evaluating integer expressions

12. Running UNIX commands

12.1 Executing simple commands
12.2 Reading the output of commands
12.3 Exit codes
12.4 Making names for temporary files

13. Miscellaneous builtin macros

13.1 Printing error messages
13.2 Exiting from m4

14. Fast loading of frozen states
15. Compatibility with other versions of m4

15.1 Extensions in GNU m4
15.2 Facilities in System V m4 not in GNU m4
15.3 Other incompatibilities

Concept index
Macro index