What does wildcard do in makefile?

What does wildcard do in makefile?

The Function wildcard $(wildcard pattern …) This string, used anywhere in a makefile, is replaced by a space-separated list of names of existing files that match one of the given file name patterns. If no existing file name matches a pattern, then that pattern is omitted from the output of the wildcard function.

What does $< mean in Makefile?

The $@ and $< are called automatic variables. The variable $@ represents the name of the target and $< represents the first prerequisite required to create the output file.

What is filter in makefile?

makefile gnu-make. From the docs: $(filter PATTERN…,TEXT) Returns all whitespace-separated words in TEXT that do match any of the PATTERN words, removing any words that do not match. The patterns are written using % , just like the patterns used in the patsubst function above.

What is symbol in makefile?

Special characters in a makefile In commands, a percent symbol ( % ) is a file specifier. To represent % literally in a command, specify a double percent sign ( %% ) in place of a single one.

How do I print in makefile?

The print-X directs make to “build” the target named print-X. Since there isn’t an explicit rule to build print-X GNU Make looks for a pattern and finds print-% (the % acts as a wildcard) and runs the associated command. (e.g. Whether it was defined in a Makefile, on the command-line, or in the environment).

How do you use variables in makefile?

How to Use Variables

1. A variable is a name defined in a makefile to represent a string of text, called the variable’s value.
2. To substitute a variable’s value, write a dollar sign followed by the name of the variable in parentheses or braces: either `$(foo)’ or `${foo}’ is a valid reference to the variable foo .

What is Percent symbol in makefile?

1 Answer. As you can read in the GNU make manual, the percent acts as a wildcard. The first argument of the patsubst function forms the pattern. Each item/word in the last argument is compared against this pattern, and if it matches, it is replaced with the second argument.

What is include in makefile?

The include directive tells make to suspend reading the current makefile and read one or more other makefiles before continuing. The directive is a line in the makefile that looks like this: include filenames … filenames can contain shell file name patterns.

What is Patsubst in makefile?

$(patsubst PATTERN,REPLACEMENT,TEXT) Finds whitespace-separated words in TEXT that match PATTERN and replaces them with REPLACEMENT. Here PATTERN may contain a % which acts as a wildcard, matching any number of any characters within a word.

What does $< mean in Linux?

$< is: The name of the first prerequisite. If the target got its recipe from an implicit rule, this will be the first prerequisite added by the implicit rule. You can see complete manual here. https://unix.stackexchange.com/questions/116547/what-do-and-in-a-makefile-mean/116548#116548.