I have created a (very simple) makefile:
DEBUG = -DDEBUG
main: main.c add.c
gcc $(DEBUG) main.c add.c -o main -lm
What I want (and don't understand how to do), is to create the makefile so that if the user prints make debug, the code will compile with the debug option, but when printing only make, the debug will be left out. What is the best way to do this?
You probably are looking for something like
main: main.c add.c
gcc $(DEBUG) main.c add.c -o main -lm
debug: DEBUG = -DDEBUG
debug: main
This may be late, ...
The basic idea is to build all objects in the subdirectory, say ./build.
We create a release file in ./build when we compile with make and create a debug file when make debug. So if there is a release file when make debug, remove everything in ./build and then build.
all: $(BD)/release $(bin1) $(bin2)
debug: CFLAGS += -g -DDEBUG=1
debug: CXXFLAGS += -g -DDEBUG=1
debug: $(BD)/debug $(bin1) $(bin2)
$(BD)/%.o: %.c Makefile # changes in Makefile will cause a rebuild
#mkdir -p $(BD)
$(CC) $(CFLAGS) -c -o $# $<
$(BD)/%.o: %.cpp Makefile
#mkdir -p $(BD)
$(CXX) $(CXXFLAGS) -c -o $# $<
$(BD)/release:
#if [ -e $(BD)/debug ]; then rm -rf $(BD); fi
#mkdir -p $(BD)
#touch $(BD)/release
$(BD)/debug:
#if [ -e $(BD)/release ]; then rm -rf $(BD); fi
#mkdir -p $(BD)
#touch $(BD)/debug
I came up with this solution, that depends on bash variable substitution.
Makefile:
main: main.c add.c
${CC} `echo $${DEBUG+-DDEBUG}` main.c add.c -o main -lm
When environment variable DEBUG is defined to anything (even blank), this makefile will substitute the -DDEBUG useful to the compiler. So invocation looks like:
DEBUG=1 make main
Related
So I have two C files which are master.c, slave.c and then config.h and I'm trying to build a makefile for the execution of these files and I'm getting an error.
I'm using a normal terminal on MacOS and when executing make I get the following error:
ss#US3FHIM0XQ86TJG: ~/project-2[master*]$ make
gcc -o master config.h master.c -g -I -std=gnu99
clang: error: cannot specify -o when generating multiple output files
make: *** [master] Error 1
Here is what my makefile looks like:
CC = gcc
CFLAGS = -g -I -std=gnu99
all: master slave
master: config.h master.c
$(CC) -o $# $^ $(CFLAGS)
slave: config.h slave.c
$(CC) -o $# $^ $(CFLAGS)
clean:
rm master slave cstest logfile.*
Can someone spot what might be causing this issue?
Remove config.h. You can compile it on the command line and omit "config.h", ie:
gcc -o master master.c -g -I -std=gnu99
Some people like to put that -o at the end:
gcc -g -I -std=gnu99 -c master.c -o master
A more appropriate way would be:
gcc -g -I/usr/include -std=gnu99 -c master.c -o master
Generally, the -I has a path, such as -I/usr/include, but you can omit the -I as your compiler usually looks there first.
Also, you may have to tweak your Makefile and omit the config.h if it is happening when you type make.
Some little errors you can fix by compiling the object by hand (ie, as above, gcc -g -I/usr/include -std=gnu99 -c master.c -o master)
Once you edit Makefile and remove config.h, and perhaps use -I/usr/include or path to your headers, you can run:
make clean
make all
or just:
make slave
or:
make master
etc, etc
$^ is a placeholder for the list of dependencies. That is why the rule
master: config.h master.c
$(CC) -o $# $^ $(CFLAGS)
runs the command
gcc -o master config.h master.c -g -I -std=gnu99
Compiling .h produces one output, compiling .c produces another output. The compiler does not know to which of them to apply -o. The proper way is using rules
master: master.c config.h
$(CC) -o $# $< $(CFLAGS)
slave: slave.c config.h
$(CC) -o $# $< $(CFLAGS)
$< is a placeholder for the first item in the list of dependencies. These rules run gcc properly
gcc -o master master.c -g -I -std=gnu99
gcc -o slave slave.c -g -I -std=gnu99
I have 4 files: 1.c, 1.h, 2.c, 2.h.
I need a makefile, which will create a dynamic library (.so) from those 4 files.
I have tried to write a makefile like this:
library.so : 1.c 1.h 2.c 2.h
but it did not work. It would be great, if someone helps me, thanks.
Something like
CC=gcc
CFLAGS= -Wall -g -O -fPIC
RM= rm -f
.PHONY: all clean
all: library.so
clean:
$(RM) *.o *.so
library.so: 1.o 2.o
$(LINK.c) -shared $^ -o $#
1.o: 1.c 1.h 2.h
2.o: 2.c 1.h 2.h
But this is untested! I am assuming Linux with GNU make, and a directory containing only the source code of your library (with the above Makefile), which might be bad practice -you might want a test case- (you could have a special Makefile rule for %.pic.o depending on %.c, etc...)
Hints: use make -p to understand the builtin rules. Then make --trace or (with remake) remake -x to understand a bit more what make is doing.
Read also Drepper's paper: How to Write Shared Libraries, documentation of GNU make, Program Library HowTo, this answer, ...
The simplest way is:
CXXFLAGS += -fPIC
CXXFLAGS += -O3
x.so: 1.o 2.o
$(LINK.cc) -shared $^ $(LOADLIBS) $(LDLIBS) -o $#
Slightly more advanced:
CC = gcc
FLAGS = # -std=gnu99 -Iinclude
CFLAGS = -fPIC -g #-pedantic -Wall -Wextra -ggdb3
LDFLAGS = -shared
DEBUGFLAGS = -O0 -D _DEBUG
RELEASEFLAGS = -O2 -D NDEBUG -combine -fwhole-program
TARGET = example.so
SOURCES = $(wildcard *.c)
HEADERS = $(wildcard *.h)
OBJECTS = $(SOURCES:.c=.o)
all: $(TARGET)
$(TARGET): $(OBJECTS)
$(CC) $(FLAGS) $(CFLAGS) $(DEBUGFLAGS) -o $(TARGET) $(OBJECTS)
CC = gcc # C compiler
CFLAGS = -fPIC -Wall -Wextra -g # C flags
LDFLAGS = -shared # linking flags
RM = rm -f # rm command
TARGET_LIB = sh_main.so # target lib
SRCS = add.c sub.c main.c # source file
DEPS = header.h # header file
OBJS = $(SRCS:.c=.o) # object file
.PHONY: all
all: ${TARGET_LIB}
$(TARGET_LIB): $(OBJS)
$(CC) ${LDFLAGS} -o $# $^ # -o $# says, put the output of the compilation in the file named on the left side of the :
$(SRCS:.c=.d):%.d:%.c
$(CC) $(CFLAGS) -MM $< >$# # the $< is the first item in the dependencies list, and the CFLAGS macro is defined as above
include $(SRCS:.c=.d)
.PHONY: clean
clean:
-${RM} ${TARGET_LIB} ${OBJS} $(SRCS:.c=.d)
After the shared library created successfully. We need to install it.
Become the root user.
Copy the shared library into standard directory "/usr/lib".
Run ldcofig command.
Recompile your .c file with shared library.
root#Admin:~/C/SharedLibrary# gcc -c main.c
root#Admin:~/C/SharedLibrary# gcc -o main main.o sh_main.so
root#Admin:~/C/SharedLibrary# ldd main
Note: In my case.
main.c: main C file
sh_main.so: shared library.
I'm no gnu make expert, this seems reasonable to me
CFLAGS+=-fPIC
%.so: ; $(LINK.c) $(LDFLAGS) -shared $^ -o $#
library.so: 1.o 2.o # default target first
# changes to `1.h` imply `1.o` needs to be rebuilt
1.o: 1.h
2.o: 2.h
When I do practice , I have a practice path.
Under this path , I have an Include path named myInclude (I have some useful function is this folder and I always use it.)
And a code path named symbol_try.I always make add new folder (with a c file and main function in it) in symbol_try and compile it.
Each time I have to compile it by gcc in terminal .Its a boring work , so I write a Makefile.
Here is an example:
the main Makefile in practice path:
FOBJS=
include myInclude/Rule.mk
include symbol_try/codeList_13.1/Rule.mk
symbol:$(FOBJS) <==What exactly I what . A executable file.
gcc -o symbol $(FOBJS) -pthread -lpthread
subsystem:
cd myInclude/ && $(MAKE)
cd symbol_try/codeList_13.1/ &&$(MAKE)
clean:
rm -rf symbol
In the myInclude/Rule.mk
FOBJS+=myInclude/otherFunction.o myInclude/error.o \
myInclude/unit.o myInclude/unitTest.o\
In the symbol_try/codeList_13.1/Rule.mk
FOBJS+=symbol_try/codeList_13.1/codeList_13.1.o
In myInclude/Makefile:
OBJS=otherFunction.o error.o unit.o unitTest.o
ALL:$(OBJS)
.PHONY:ALL
$(OBJS):%.o:%.c
gcc -c $< -o $#
clean :
otherFunction.o error.o unit.o
In symbol_try/codeList_13.1/Makefile:
codeList_13.1.o:codeList_13.1.c
gcc -c codeList_13.1.c
Well.That can work. But as you see , I have to write a Rule.mk(to initialize the FOBJS) and a Makefile for each folder.
I am new for make , I want find a way more concise , witch I only need write one Makefile for each folder and a main Makefile.No Rule.mk any more.
PS: I always change the code in myInclude ,so I don't want to build it a library.
Thanks for any help.
Here's one way you can do it with just one Makefile:
CC = gcc
CPPFLAGS += -I myInclude/ (1)
CFLAGS += -std=c99 -Wall (2)
VPATH = myInclude/ \ (3)
symbol_try/codeList_13.1/
symbol: otherFunction.o error.o unit.o unitTest.o codeList_13.1.o (4)
$(CC) -o $# $^ (5)
.PHONY : clean
clean:
rm -f symbol *.o
Note that make knows how to build C files and has some standard macros: CC, CPPFLGAS, CFLAGS
Add the include paths of your headers. You presumably have some headers for the individual object files in the myInclude directory.
Put the compiler flags here.
Add the paths to the source files you want to build.
List the object files that the executable depends upon
As there is no file called symbol.c you need to tell make how to create symbol.o with a rule. $# means the target ('symbol', here), and $^ means all of the prerequisites (the object files listed).
Here's a list of all of the files in my test directories for this:
$ find . -type f
.
./Makefile
./myInclude/error.c
./myInclude/header.h
./myInclude/otherFunction.c
./myInclude/unit.c
./myInclude/unitTest.c
./symbol_try/codeList_13.1/codeList_13.1.c
And the build output:
$ make
gcc -std=c99 -Wall -I myInclude/ -c -o otherFunction.o myInclude/otherFunction.c
gcc -std=c99 -Wall -I myInclude/ -c -o error.o myInclude/error.c
gcc -std=c99 -Wall -I myInclude/ -c -o unit.o myInclude/unit.c
gcc -std=c99 -Wall -I myInclude/ -c -o unitTest.o myInclude/unitTest.c
gcc -std=c99 -Wall -I myInclude/ -c -o codeList_13.1.o symbol_try/codeList_13.1/codeList_13.1.c
gcc -o symbol otherFunction.o error.o unit.o unitTest.o codeList_13.1.o
Why don't you create a library from the objects in myInclude and do the linking in the Makefile in your code path (symbol_try/codeList_13.1). The latter is better anyway because the needed libraries (-pthread -lpthread in your case) might change as well for some other code.
The main Makefile now would have got nothing to do but call make in all needed subdirectories.
In each folder have a makefile with
SOURCES=sample.c sampletest.c
OBJECTS=$(SOURCES:%.c=$(OBJDIR)/%.o)
all: $(OBJECTS)
$(OBJDIR)/%.o: %.c
$(CC) $(CFLAGS) -o $# $<
In the root directory of a project, create a makefile with a rule to compile every sub-folder like the below.
Dirs= path-to-rootdir
objs:
set -e ; \
for i in $(Dirs) ; do \
$(MAKE) CC="$(CC)" CFLAGS="$(CFLAGS_MODULE)" LDFLAGS="$(LDFLAGS)" OBJDIR="$(OBJDIR)" -C $$i; \
done
And then you could use it build the executable by adding a rule
EXE: objs
$(CC) -L./Path1 $(LIB_PATH) -llib1 -o $(EXE_NAME) $(wildcard $(OBJDIR)/*.o)
Hope this helps!!!
I am trying to write a makefile which uses macros to create multiple executables from multiple files at once. I tried searching through previously answered questions but, because I am fairly new to programming in C as well as working with gcc, I was not able to find an answer to my question.
Here is what I have so far:
CC=gcc
CFLAGS=-I.
OBJ = ex1.c ex3.c
EXECUTABLE = ex1 ex3
$(EXECUTABLE): $(OBJ)
gcc -o $# $^ $(CFLAGS)
clean:
rm -f $(EXECUTABLE)
I would like the line
$(EXECUTABLE): $(OBJ)
to create executables ex1 and ex3 from files ex1.c ex3.c respectively.
For this particular case, where each executable has a single source file with .c extension, all you need is a one line Makefile:
all: ex1 ex3
The built-in default rules for make then work already:
$ make
cc -O2 -pipe ex1.c -o ex1
cc -O2 -pipe ex3.c -o ex3
Behind the scene, make is using the POSIXly mandated built-in single suffix rule
.c:
$(CC) $(CFLAGS) $(LDFLAGS) -o $# $<
Vary the command to your liking with make CC=gcc CFLAGS=-O2 LDFLAGS=-s and similar.
Trivia of the day: in fact, if you are willing to name the targets when invoking make, you can use an empty or even run without any Makefile:
$ make -f /dev/null CC=gcc CFLAGS=-O2 LDFLAGS=-s ex1 ex3
gcc -O2 -s ex1.c -o ex1
gcc -O2 -s ex3.c -o ex3
$ rm -f Makefile ex1 ex3
$ make CC=gcc CFLAGS=-O2 LDFLAGS=-s ex1 ex3
gcc -O2 -s ex1.c -o ex1
gcc -O2 -s ex3.c -o ex3
Make magic!
As a rule of thumb, don't reinvent the wheel (or rules), use the rules that are already there. It simplifies your and make's life a lot. This makes for small and sexy makefiles to impress the ladies with :-)
Some suggestions (assuming you use GNU make, not something else)
First, run once make -p, you'll understand what builtin rules make is knowing. Look in particular for COMPILE.c and LINK.c
Then, I suggest
CFLAGS= -g -Wall -I.
(because you really want -g for debugging, and -Wall to get most warnings)
And you probably don't need
$(EXECUTABLE): $(OBJ)
gcc -o $# $^ $(CFLAGS)
However, I suggest adding before most other rules
.PHONY: all clean
all: $(EXECUTABLES)
Actually, I would code your Makefile (for GNU make!) as follow
# file Makefile
CC= gcc
RM= rm -vf
CFLAGS= -Wall -g
CPPFLAGS= -I.
SRCFILES= ex1.c ex2.c ## or perhaps $(wildcard *.c)
OBJFILES= $(patsubst %.c, %.o, $(SRCFILES))
PROGFILES= $(patsubst %.c, %, $(SRCFILES))
.PHONY: all clean
all: $(PROGFILES)
clean:
$(RM) $(OBJFILES) $(PROGFILES) *~
## eof Makefile
Remember that tab is a significant character in Makefile-s (action part of rules). In this answer, lines starting with four spaces at least should really start with a tab character.
Once everything is debugged consider running make clean to clean everything, and then make -j CFLAGS=-O2 all to compile in parallel everything with optimizations.
At last, I recommend using remake and running remake -x to debug complex Makefile-s
Of course, I'm supposing that your directory has only single-file programs.
BTW, there are other build automation tools. Perhaps you might consider using omake or ninja. For building large programs (millions of source code lines) consider also automake, ccache, cmake, icecream. In some cases, consider generating some C code with GPP, GNU bison, SWIG, etc... or using your own Python or Guile script (or C meta-program). See also this draft report.
Don't forget to use a version control system like git for your source files. It is also time to learn such a tool.
The following answer includes multiple executable such as initiate, process1, process2, ..., process4.
LOCAL_INCLUDE=./
all: clean process_first process_second init
process_first:
gcc -g -o process1 -I$(LOCAL_INCLUDE) process1.c -lzmq -L. -L./.
gcc -g -o process2 -I$(LOCAL_INCLUDE) process2.c -lzmq -L. -L./.
process_second:
gcc -g -o process3 -I$(LOCAL_INCLUDE) process3.c -lzmq -L. -L./.
gcc -g -o process4 -I$(LOCAL_INCLUDE) process4.c -lzmq -L. -L./.
init:
gcc -g -o initiate -I$(LOCAL_INCLUDE) initiate.c -lzmq -lconfig -lpthread -L. -L./. -ldl -lrt
clean:
rm -rf init_manager.o init_manager
rm -rf process1 process2 process3 process4
NOTE: It is a good practice to clean and touch all the executable files before making them again.
You're close, but you need a pattern rule:
$(EXECUTABLE): % : %.c
And then a default rule to make it build both:
all: $(EXECUTABLE)
Have a reference makefile that im slowly editing and using which spits out these two errors
Makefile:25: warning: overriding commands for target `build/semanticHash'
Makefile:21: warning: ignoring old commands for target `build/semanticHash'
make: Circular build/semanticHash <- build/semanticHash dependency dropped.
cc -g -ldl -lgsl -lgslcblas -lzmq -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG -fPIC -c -o src/semanticHash/rmb.o src/semanticHash/rmb.c
I'm new to makefile syntax and rules, so any common mistakes I Google for, but no luck for myself in this case.
So the question is, where am I causing these errors, and is there any patterns that I should avoid in my current makefile?
CFLAGS= -g $(LIBS) -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG $(OPTFLAGS)
LIBS= -ldl $(OPTLIBS)
PREFIX?=/usr/local
OPTLIBS= -lgsl -lgslcblas -lzmq
SOURCES=$(wildcard src/**/*.c src/*.c)
OBJECTS=$(patsubst %.c,%.o,$(SOURCES))
TEST_SRC=$(wildcard tests/*_tests.c)
TESTS=$(patsubst %.c,%,$(TEST_SRC))
TARGET=build/semanticHash # Rename to library !!!!!
SO_TARGET=$(patsubst %.a,%.so,$(TARGET))
# The Target Build
all: $(TARGET) tests
$(TARGET): CFLAGS += -fPIC
$(TARGET): build $(OBJECTS)
ar rcs $# $(OBJECTS)
ranlib $#
$(SO_TARGET): $(TARGET) $(OBJECTS)
$(CC) -shared -o $# $(OBJECTS)
build:
#mkdir -p build
#mkdir -p bin
# The Unit Tests
.PHONY: tests
tests: CFLAGS += $(TARGET)
tests: $(TESTS)
sh ./tests/runtests.sh
valgrind:
VALGRIND="valgrind --log-file=/tmp/valgrind-%p.log" $(MAKE)
# The Cleaner
clean:
rm -rf build $(OBJECTS) $(TESTS)
rm -f tests/tests.log
find . -name "*.gc*" -exec rm {} \;
rm -rf `find . -name "*.dSYM" -print`
# The Install
install: all
install -d $(DESTDIR)/$(PREFIX)/lib/
install $(TARGET) $(DESTDIR)/$(PREFIX)/lib/
You set SO_TARGET to the same as TARGET:
TARGET=build/semanticHash # Rename to library !!!!!
SO_TARGET=$(patsubst %.a,%.so,$(TARGET))
As seen TARGET does not end with .a, so nothing will be substituted making SO_TARGET the same.
Later you have
$(SO_TARGET): $(TARGET) $(OBJECTS)
As both SO_TARGET and TARGET are the same, you have a circular dependency.
The other two warnings are because of this issue as well, as you have conflicting commands for the same target.
On an unrelated note, you should not mix compiler and linker flags like you do. Compiler flags are for compilation, linker flags for linking. You should also change the order of the linker options, and place the libraries to link with after the object files. This is because the GNU linker doesn't load libraries if there isn't anything depending on them, and dependencies are not loaded until it loads the object files.