Make

The make tool

It's fame: it is included in Unix since 1977

Its input: it reads a script called "Makefile"

Its operation: it is intimately bound to the execution environment shell

Its support: environment dependency checkers, IDEs, makefile generators

Its handy feature: defaults exist in the absence of a target or the whole makefile

Its limit: makefile portability and language syntax

Make is to C what Ant to Java (update: Maven or Gradle)

# this is a simple makefile

CC=gcc
CFLAGS=-g -O3 #-v

OBJS=hello.o
EXE=hello

all: $(EXE)

$(EXE): $(OBJS)
    $(CC) $(CFLAGS) -o $@ $(OBJS)

clean:
    rm -rf $(OBJS) $(EXE)
    
.SUFFIXES: .c .o

%.0: %.c
    $(CC) -c $(CFLAGS( $<

• line comments starts with hash '#'

• macro declaration: MACRO=line of values

• macro use: $(MACRO)

• targets:

  • target: dep1 dep2

  • traditionally the first target is called 'all'

  • target commands come in a line following target

  • command line begins with <TAB>!

  • command line is batch in Windows, bash in Unix

  • multiple commands come line after line, always <TAB> indented

  • one command line = one shell session (how to change shell environment then?)

  • the internal macro $@ contains the name of the current target

• traditionally there is a target 'clean' to reset the environment

• %.o: %.c - implicit/suffix rules based on file extensions

• the internal macro $< fives the "from" value on implicit rules

• the .SUFFIXES list the set of file extensions the implicit rules work on

Running make

Simplest form:

$ make

• Searches for files 'makefile', then 'Makefile' in the current directory

• Executes the first target declared in the makefile

Specify the makefile:

$ make -f myMakefile

Pointing the targets to be executed in order:

$ make clean all

Give environment variables precedence:

$ make -e

Ignore all errors in command execution:

$ make -i

Silent mode - do not output te command lines :

$ make -s