Introduction to make

make

make

  • Automatically build software / libraries / documents by specifying dependencies via a Makefile

  • Originally created by Stuart Feldman in 1976 at Bell Labs

  • Almost universally available (all flavors of unix / linux / osx)

Makefile

A Makefile provides a list of target files along with their dependencies and the steps necessary to generate each of the targets.

target1: depend1 depend2 depend3 ...
    step1
    step2
    step3
    ...

depend1: depend1.1
    step1
    step2

Makefile (simple example)

paper.html: paper.Rmd Fig1/fig.png Fig2/fig.png
    Rscript -e "library(rmarkdown);render('paper.Rmd')"

Fig1/fig.png: Fig1/fig.R
    cd Fig1;Rscript fig.R

Fig2/fig.png: Fig2/fig.R
    cd Fig2;Rscript fig.R

Intelligent Building

Because the Makefile specifies the dependency structure make knows when a file has changed (by examining the file’s modification timestamp) and only runs the steps that depend on the file(s) that have changed.


  • After running make the first time, I edit paper.Rmd, what steps run if I run make again?

  • What about editing Fig1/fig.R?

Variables

Like R or shell scripts or any other language we can define variables

R_OPTS=--no-save --no-restore --no-site-file --no-init-file --no-environ

Fig1/fig.png: Fig1/fig.R
    cd Fig1;Rscript $(R_OPTS) fig.R

Special Targets

By default is you run make without arguments it will attempt to build the first target in the Makefile whose name does not start with a .. By convention we often include an all target which explicitly specifies how to build everything within the project.


all is an example of what is called a phony target - because there is no all file in the directory. Other common phony targets:

  • clean - remove any files created by the Makefile, restores to the original state

  • install - for software packages, installs the compiled programs / libraries / headers


We list all phony targets by including the line like the following:

.PHONY: all clean all

Builtin Variables

  • $@    the file name of the target

  • $<    the name of the first dependency

  • $^    the names of all dependencies

  • $(@D)    the directory part of the target

  • $(@F)    the file part of the target

  • $(<D)    the directory part of the first dependency

  • $(<F)    the file part of the first dependency

Pattern Rules

Often we want to build several files in the same way, in these cases we can use % as a special wildcard character to match both targets and dependencies.

So we can go from

Fig1/fig.png: Fig1/fig.R
    cd R;Rscript fig.R

Figs2/fig.png: Fig1/fig.R
    cd R;Rscript fig.R

to

Fig%/fig.png: Fig%/fig.R
    cd $(<D);Rscript $(<F)

Makefile (fancy example)

all: paper.html

paper.html: paper.Rmd Fig1/fig.png Fig2/fig.png
    Rscript -e "library(rmarkdown);render('paper.Rmd')"

Fig%/fig.png: Fig%/fig.R
    cd $(<D);Rscript $(<F)

clean:
    rm -f paper.html
    rm -f Fig*/*.png

.PHONY: all clean

HW4’s Makefile





Live Demo

Acknowledgments

Acknowledgments

Above materials are derived from the following sources: