diff options
Diffstat (limited to 'make.html.markdown')
-rw-r--r-- | make.html.markdown | 491 |
1 files changed, 245 insertions, 246 deletions
diff --git a/make.html.markdown b/make.html.markdown index eecc96bf..5269e436 100644 --- a/make.html.markdown +++ b/make.html.markdown @@ -1,246 +1,245 @@ ----
-category: tool
-tool: make
-contributors:
- - ["Robert Steed", "https://github.com/robochat"]
- - ["Stephan Fuhrmann", "https://github.com/sfuhrm"]
-filename: Makefile
----
-
-A Makefile defines a graph of rules for creating a target (or targets).
-Its purpose is to do the minimum amount of work needed to update a
-target to the most recent version of the source. Famously written over a
-weekend by Stuart Feldman in 1976, it is still widely used (particularly
-on Unix and Linux) despite many competitors and criticisms.
-
-There are many varieties of make in existence, however this article
-assumes that we are using GNU make which is the standard on Linux.
-
-```make
-
-# Comments can be written like this.
-
-# File should be named Makefile and then can be run as `make <target>`.
-# Otherwise we use `make -f "filename" <target>`.
-
-# Warning - only use TABS to indent in Makefiles, never spaces!
-
-#-----------------------------------------------------------------------
-# Basics
-#-----------------------------------------------------------------------
-
-# Rules are of the format
-# target: <prerequisite>
-# where prerequisites are optional.
-
-# A rule - this rule will only run if file0.txt doesn't exist.
-file0.txt:
- echo "foo" > file0.txt
- # Even comments in these 'recipe' sections get passed to the shell.
- # Try `make file0.txt` or simply `make` - first rule is the default.
-
-# This rule will only run if file0.txt is newer than file1.txt.
-file1.txt: file0.txt
- cat file0.txt > file1.txt
- # use the same quoting rules as in the shell.
- @cat file0.txt >> file1.txt
- # @ stops the command from being echoed to stdout.
- -@echo 'hello'
- # - means that make will keep going in the case of an error.
- # Try `make file1.txt` on the commandline.
-
-# A rule can have multiple targets and multiple prerequisites
-file2.txt file3.txt: file0.txt file1.txt
- touch file2.txt
- touch file3.txt
-
-# Make will complain about multiple recipes for the same rule. Empty
-# recipes don't count though and can be used to add new dependencies.
-
-#-----------------------------------------------------------------------
-# Phony Targets
-#-----------------------------------------------------------------------
-
-# A phony target. Any target that isn't a file.
-# It will never be up to date so make will always try to run it.
-all: maker process
-
-# We can declare things out of order.
-maker:
- touch ex0.txt ex1.txt
-
-# Can avoid phony rules breaking when a real file has the same name by
-.PHONY: all maker process
-# This is a special target. There are several others.
-
-# A rule with a dependency on a phony target will always run
-ex0.txt ex1.txt: maker
-
-# Common phony targets are: all make clean install ...
-
-#-----------------------------------------------------------------------
-# Automatic Variables & Wildcards
-#-----------------------------------------------------------------------
-
-process: file*.txt #using a wildcard to match filenames
- @echo $^ # $^ is a variable containing the list of prerequisites
- @echo $@ # prints the target name
- #(for multiple target rules, $@ is whichever caused the rule to run)
- @echo $< # the first prerequisite listed
- @echo $? # only the dependencies that are out of date
- @echo $+ # all dependencies including duplicates (unlike normal)
- #@echo $| # all of the 'order only' prerequisites
-
-# Even if we split up the rule dependency definitions, $^ will find them
-process: ex1.txt file0.txt
-# ex1.txt will be found but file0.txt will be deduplicated.
-
-#-----------------------------------------------------------------------
-# Patterns
-#-----------------------------------------------------------------------
-
-# Can teach make how to convert certain files into other files.
-
-%.png: %.svg
- inkscape --export-png $^
-
-# Pattern rules will only do anything if make decides to create the
-# target.
-
-# Directory paths are normally ignored when matching pattern rules. But
-# make will try to use the most appropriate rule available.
-small/%.png: %.svg
- inkscape --export-png --export-dpi 30 $^
-
-# make will use the last version for a pattern rule that it finds.
-%.png: %.svg
- @echo this rule is chosen
-
-# However make will use the first pattern rule that can make the target
-%.png: %.ps
- @echo this rule is not chosen if *.svg and *.ps are both present
-
-# make already has some pattern rules built-in. For instance, it knows
-# how to turn *.c files into *.o files.
-
-# Older makefiles might use suffix rules instead of pattern rules
-.png.ps:
- @echo this rule is similar to a pattern rule.
-
-# Tell make about the suffix rule
-.SUFFIXES: .png
-
-#-----------------------------------------------------------------------
-# Variables
-#-----------------------------------------------------------------------
-# aka. macros
-
-# Variables are basically all string types
-
-name = Ted
-name2="Sarah"
-
-echo:
- @echo $(name)
- @echo ${name2}
- @echo $name # This won't work, treated as $(n)ame.
- @echo $(name3) # Unknown variables are treated as empty strings.
-
-# There are 4 places to set variables.
-# In order of priority from highest to lowest:
-# 1: commandline arguments
-# 2: Makefile
-# 3: shell environment variables - make imports these automatically.
-# 4: make has some predefined variables
-
-name4 ?= Jean
-# Only set the variable if environment variable is not already defined.
-
-override name5 = David
-# Stops commandline arguments from changing this variable.
-
-name4 +=grey
-# Append values to variable (includes a space).
-
-# Pattern-specific variable values (GNU extension).
-echo: name2 = Sara # True within the matching rule
- # and also within its remade recursive dependencies
- # (except it can break when your graph gets too complicated!)
-
-# Some variables defined automatically by make.
-echo_inbuilt:
- echo $(CC)
- echo ${CXX}
- echo $(FC)
- echo ${CFLAGS}
- echo $(CPPFLAGS)
- echo ${CXXFLAGS}
- echo $(LDFLAGS)
- echo ${LDLIBS}
-
-#-----------------------------------------------------------------------
-# Variables 2
-#-----------------------------------------------------------------------
-
-# The first type of variables are evaluated each time they are used.
-# This can be expensive, so a second type of variable exists which is
-# only evaluated once. (This is a GNU make extension)
-
-var := hello
-var2 ::= $(var) hello
-#:= and ::= are equivalent.
-
-# These variables are evaluated procedurally (in the order that they
-# appear), thus breaking with the rest of the language !
-
-# This doesn't work
-var3 ::= $(var4) and good luck
-var4 ::= good night
-
-#-----------------------------------------------------------------------
-# Functions
-#-----------------------------------------------------------------------
-
-# make has lots of functions available.
-
-sourcefiles = $(wildcard *.c */*.c)
-objectfiles = $(patsubst %.c,%.o,$(sourcefiles))
-
-# Format is $(func arg0,arg1,arg2...)
-
-# Some examples
-ls: * src/*
- @echo $(filter %.txt, $^)
- @echo $(notdir $^)
- @echo $(join $(dir $^),$(notdir $^))
-
-#-----------------------------------------------------------------------
-# Directives
-#-----------------------------------------------------------------------
-
-# Include other makefiles, useful for platform specific code
-include foo.mk
-
-sport = tennis
-# Conditional compilation
-report:
-ifeq ($(sport),tennis)
- @echo 'game, set, match'
-else
- @echo "They think it's all over; it is now"
-endif
-
-# There are also ifneq, ifdef, ifndef
-
-foo = true
-
-ifdef $(foo)
-bar = 'hello'
-endif
-```
-
-### More Resources
-
-+ [gnu make documentation](https://www.gnu.org/software/make/manual/)
-+ [software carpentry tutorial](http://swcarpentry.github.io/make-novice/)
-+ learn C the hard way [ex2](http://c.learncodethehardway.org/book/ex2.html) [ex28](http://c.learncodethehardway.org/book/ex28.html)
+--- +category: tool +tool: make +contributors: + - ["Robert Steed", "https://github.com/robochat"] + - ["Stephan Fuhrmann", "https://github.com/sfuhrm"] +filename: Makefile +--- + +A Makefile defines a graph of rules for creating a target (or targets). +Its purpose is to do the minimum amount of work needed to update a +target to the most recent version of the source. Famously written over a +weekend by Stuart Feldman in 1976, it is still widely used (particularly +on Unix and Linux) despite many competitors and criticisms. + +There are many varieties of make in existence, however this article +assumes that we are using GNU make which is the standard on Linux. + +```make +# Comments can be written like this. + +# File should be named Makefile and then can be run as `make <target>`. +# Otherwise we use `make -f "filename" <target>`. + +# Warning - only use TABS to indent in Makefiles, never spaces! + +#----------------------------------------------------------------------- +# Basics +#----------------------------------------------------------------------- + +# Rules are of the format +# target: <prerequisite> +# where prerequisites are optional. + +# A rule - this rule will only run if file0.txt doesn't exist. +file0.txt: + echo "foo" > file0.txt + # Even comments in these 'recipe' sections get passed to the shell. + # Try `make file0.txt` or simply `make` - first rule is the default. + +# This rule will only run if file0.txt is newer than file1.txt. +file1.txt: file0.txt + cat file0.txt > file1.txt + # use the same quoting rules as in the shell. + @cat file0.txt >> file1.txt + # @ stops the command from being echoed to stdout. + -@echo 'hello' + # - means that make will keep going in the case of an error. + # Try `make file1.txt` on the commandline. + +# A rule can have multiple targets and multiple prerequisites +file2.txt file3.txt: file0.txt file1.txt + touch file2.txt + touch file3.txt + +# Make will complain about multiple recipes for the same rule. Empty +# recipes don't count though and can be used to add new dependencies. + +#----------------------------------------------------------------------- +# Phony Targets +#----------------------------------------------------------------------- + +# A phony target. Any target that isn't a file. +# It will never be up to date so make will always try to run it. +all: maker process + +# We can declare things out of order. +maker: + touch ex0.txt ex1.txt + +# Can avoid phony rules breaking when a real file has the same name by +.PHONY: all maker process +# This is a special target. There are several others. + +# A rule with a dependency on a phony target will always run +ex0.txt ex1.txt: maker + +# Common phony targets are: all make clean install ... + +#----------------------------------------------------------------------- +# Automatic Variables & Wildcards +#----------------------------------------------------------------------- + +process: file*.txt #using a wildcard to match filenames + @echo $^ # $^ is a variable containing the list of prerequisites + @echo $@ # prints the target name + #(for multiple target rules, $@ is whichever caused the rule to run) + @echo $< # the first prerequisite listed + @echo $? # only the dependencies that are out of date + @echo $+ # all dependencies including duplicates (unlike normal) + #@echo $| # all of the 'order only' prerequisites + +# Even if we split up the rule dependency definitions, $^ will find them +process: ex1.txt file0.txt +# ex1.txt will be found but file0.txt will be deduplicated. + +#----------------------------------------------------------------------- +# Patterns +#----------------------------------------------------------------------- + +# Can teach make how to convert certain files into other files. + +%.png: %.svg + inkscape --export-png $^ + +# Pattern rules will only do anything if make decides to create the +# target. + +# Directory paths are normally ignored when matching pattern rules. But +# make will try to use the most appropriate rule available. +small/%.png: %.svg + inkscape --export-png --export-dpi 30 $^ + +# make will use the last version for a pattern rule that it finds. +%.png: %.svg + @echo this rule is chosen + +# However make will use the first pattern rule that can make the target +%.png: %.ps + @echo this rule is not chosen if *.svg and *.ps are both present + +# make already has some pattern rules built-in. For instance, it knows +# how to turn *.c files into *.o files. + +# Older makefiles might use suffix rules instead of pattern rules +.png.ps: + @echo this rule is similar to a pattern rule. + +# Tell make about the suffix rule +.SUFFIXES: .png + +#----------------------------------------------------------------------- +# Variables +#----------------------------------------------------------------------- +# aka. macros + +# Variables are basically all string types + +name = Ted +name2="Sarah" + +echo: + @echo $(name) + @echo ${name2} + @echo $name # This won't work, treated as $(n)ame. + @echo $(name3) # Unknown variables are treated as empty strings. + +# There are 4 places to set variables. +# In order of priority from highest to lowest: +# 1: commandline arguments +# 2: Makefile +# 3: shell environment variables - make imports these automatically. +# 4: make has some predefined variables + +name4 ?= Jean +# Only set the variable if environment variable is not already defined. + +override name5 = David +# Stops commandline arguments from changing this variable. + +name4 +=grey +# Append values to variable (includes a space). + +# Pattern-specific variable values (GNU extension). +echo: name2 = Sara # True within the matching rule + # and also within its remade recursive dependencies + # (except it can break when your graph gets too complicated!) + +# Some variables defined automatically by make. +echo_inbuilt: + echo $(CC) + echo ${CXX} + echo $(FC) + echo ${CFLAGS} + echo $(CPPFLAGS) + echo ${CXXFLAGS} + echo $(LDFLAGS) + echo ${LDLIBS} + +#----------------------------------------------------------------------- +# Variables 2 +#----------------------------------------------------------------------- + +# The first type of variables are evaluated each time they are used. +# This can be expensive, so a second type of variable exists which is +# only evaluated once. (This is a GNU make extension) + +var := hello +var2 ::= $(var) hello +#:= and ::= are equivalent. + +# These variables are evaluated procedurally (in the order that they +# appear), thus breaking with the rest of the language ! + +# This doesn't work +var3 ::= $(var4) and good luck +var4 ::= good night + +#----------------------------------------------------------------------- +# Functions +#----------------------------------------------------------------------- + +# make has lots of functions available. + +sourcefiles = $(wildcard *.c */*.c) +objectfiles = $(patsubst %.c,%.o,$(sourcefiles)) + +# Format is $(func arg0,arg1,arg2...) + +# Some examples +ls: * src/* + @echo $(filter %.txt, $^) + @echo $(notdir $^) + @echo $(join $(dir $^),$(notdir $^)) + +#----------------------------------------------------------------------- +# Directives +#----------------------------------------------------------------------- + +# Include other makefiles, useful for platform specific code +include foo.mk + +sport = tennis +# Conditional compilation +report: +ifeq ($(sport),tennis) + @echo 'game, set, match' +else + @echo "They think it's all over; it is now" +endif + +# There are also ifneq, ifdef, ifndef + +foo = true + +ifdef $(foo) +bar = 'hello' +endif +``` + +### More Resources + ++ [gnu make documentation](https://www.gnu.org/software/make/manual/) ++ [software carpentry tutorial](http://swcarpentry.github.io/make-novice/) ++ learn C the hard way [ex2](http://c.learncodethehardway.org/book/ex2.html) [ex28](http://c.learncodethehardway.org/book/ex28.html) |