Linux makefile Study Notes

The execution steps for GNU make are as follows:

1. Read all makefiles;

2. Read Other makefiles included;

3. initialize the variables in the file;

4. Deduce concealed rules and analyze all rules;

5. create dependency links for all target files;

6. Determine the targets to be regenerated Based on the dependency relationship;

7. Run the generated command.

Step 1-5 is the first stage, and step 6-7 is the second stage. In the first phase, if the defined variable is used, make will expand it to the position in use. But make will not be fully expanded immediately. Make uses the procrastination strategy. If the variable appears in the dependency rule, it will only be used when the dependency is determined, variable is expanded within it.