makefile

This page contains notes on makefiles.

Pattern Rules

Since suffix rules have been deprecated, pattern rules should be used instead:

%.o : %.c
	# rule defining how to make a file with .o suffix from a .c file

Automatic Variables

Below are a few automatic variables commonly used in makefiles. For others, check here before writing code to define your own.

$@   filename of the target of the rule
$<   the name of the first prerequisite
$^   the name of all of the prerequisites with spaces between them
$*   the stem with which the implicit rules matches

Intermediate Objects

make removes intermediate objects by default. To save them instead, add the line:

.PRECIOUS: %.o  # example for .o suffix files

This stackoverflow thread presents several alternatives.

Example: Simple Makefile

This makefile converts markdown to html. Note that the intermediate file (suffix ihtml) will be automatically deleted by make.

# turn off implicit rules
.SUFFIXES:

# turn off deletion of intermediate files (see .PRECIOUS above)
.SECONDARY:

%.html: %.ihtml
    tpage --define mdfile=$< main.tt > $@

%.ihtml: %.md
    markdown $< > $@

clean:
    rm -f *.ihtml *.html

Links

A helpful tutorial on makefiles. It has guidelines for conventions and automatically generating dependencies.