I have a local DLL which I want to shadow the system one.
How do i do that?
Specifically (on linux):
/usr/bin/clang++ -o vw main.o -L. -l vw -l allreduce -L /usr/lib -L /usr/lib/x86_64-linux-gnu -l boost_program_options -l pthread -l z
but then
$ ldd vowpalwabbit/vw
libvw.so => /usr/lib64/libvw.so (0x00007ffa22789000)
and I want it to point to ./libvw.so instead
Afaik the parameter is -nostdlib, but I only used it with plain C.
See also Clang produces crashing code with -nostdlib
Related
I am kinda rookie in makefile field but trying to write makefile that would go in two modes: normal mode make outputing executable file called say bingo depending on some files and a mode make debug outputing executable file called bingo.debug that shall be compiled with debug option. I'm trying to use target variable with the following result:
PROGRAM = bingo
SUFIX = .debug
CC = gcc
CFLAGS = -Wall -O2
DEBUG = -g -D DEBUG
all: $(PROGRAM)
debug: CFLAGS += $(DEBUG)
debug: PROGRAM += $(SUFIX)
debug: all
file1.o: file1.c file1.h
$(CC) -c $(CFLAGS) -o $# $<
file2.o: file2.c file2.h
$(CC) -c $(CFLAGS) -o $# $<
$(PROGRAM).o: $(PROGRAM).c
$(CC) -c $(CFLAGS) -o $# $<
$(PROGRAM): file1.o file2.o ($PROGRAM).o
$(CC) -o $# $^
.PHONY: all clean
clean:
rm -rf $(PROGRAM) *.o
It looks like make debug correctly compiles the file with debug flags but it does not change the file name (i.e. both modes outputs the same bingo file). Any help much appriciated!
You cannot use target-specific variables in targets. The documentation is very clear that they are available only in recipes.
In general it's problematic to do things this way, because make has no idea which objects were built with debug and which weren't. If you forget to do a complete clean and/or run make the wrong way then you'll get a mix of different object files: some compiled with debug and some not.
Instead, you should put your debug object files in a different directory from your non-debug object files so you don't have to worry about that.
I am trying to build a very simple Makefile, that intends to use a homemade library (libf904QC.a) made of Fortran modules. The library is in /usr/local/lib64 whereas the corresponding .mod files are in /usr/local/include/f904QC
Here is the Makefile
# Makefile
NAME=NPManip
FFLAGS= -ffpe-trap=overflow -c -O3
LFLAGS=
PATH2LIB=/usr/local/lib64/
INCLUDEDIR=/usr/local/include/f904QC/
#
LIB=-L$(PATH2LIB) -I$(INCLUDEDIR) -lf904QC.a
OBJS = \
tools_NPManip.o\
NPManip.o
%.o: %.f90
gfortran $(LIB) $(FFLAGS) $*.f90
NPM: $(OBJS)
gfortran $(LFLAGS) $(OBJS) $(LIB) -o $(NAME)
clean:
#if test -e $$HOME/bin/$(NAME); then \
rm $$HOME/bin/$(NAME); \
fi
rm *.o *.mod
mrproper: clean
rm $(NAME)
install:
ln -s $(shell pwd)/$(NAME) $$HOME/bin/.
I get the following error message :
gfortran tools_NPManip.o NPManip.o -L/usr/local/lib64/ -I/usr/local/include/f904QC/ -lf904QC.a -o NPManip
/usr/lib64/gcc/x86_64-suse-linux/4.7/../../../../x86_64-suse-linux/bin/ld: cannot find -lf904QC.a
collect2: error: ld returned 1 exit status
make: * [NPM] Erreur 1
Where is the mistake? It is not obvious to me since libf904QC.o is actually located in /usr/local/lib64, which is defined by the -L option.
Thnak you for your help
You should specify either the full path to the library /usr/local/lib64/libf904QC.a or alternatively -L/usr/local/lib64 -lf90QC, without the .a in that case. From man ld:
-l namespec
--library=namespec
Add the archive or object file specified by namespec to the list of files to link. This option may be used any number of
times. If namespec is of the form :filename, ld will search the library path for a file called filename, otherwise it
will search the library path for a file called libnamespec.a.
-L searchdir
--library-path=searchdir
Add path searchdir to the list of paths that ld will search for archive libraries and ld control scripts. You may use
this option any number of times. The directories are searched in the order in which they are specified on the command
line. Directories specified on the command line are searched before the default directories. All -L options apply to
all -l options, regardless of the order in which the options appear. -L options do not affect how ld searches for a
linker script unless -T option is specified.
I have the redis server installed, and can use it from the command line. Now, I am wanting to write a client program using hiredis. To begin with, I tried to compile example.c which is present in the hiredis directory:
vishal#expmach:~/redis-2.6.14/deps/hiredis$ ls
adapters async.h COPYING dict.h *example.c* example-libevent.c
hiredis.c Makefile net.h sds.c test.c async.c CHANGELOG.md dict.c example-
ae.c example-libev.c fmacros.h hiredis.h net.c README.md sds.h
Here are the commands:
vishal#expmach:~/redis-2.6.14/deps/hiredis$ gcc -c -I hiredis example.c
vishal#expmach:~/redis-2.6.14/deps/hiredis$ gcc -o example -I hiredis -L hiredis -lhiredis -lm
/usr/bin/ld: cannot find -lhiredis
collect2: ld returned 1 exit status
I am not sure how to go about fixing this. Please help.
gcc -o example example.c -lhiredis $(pkg-config --cflags --libs glib-2.0)
why don't you juste juste the provided Makefile?
make
./hiredis-example
I'm having a hard time finding good documentation on the most common g++ options. I have the following g++ command and I'm trying to understand it well:
g++ q1.cpp -o q1 -I/usr/local/include/opencv -L/usr/local/lib -lm -lopencv_core -lopencv_highgui -lopencv_calib3d -lopencv_imgproc
What does the -I option do?
-I adds to the path for searching for include files.
-l links to a particular library. (e.g. -lm links libm which is math)
It's not for a library I think it's only for include files. (It's a i not a l, l it's for libraries)
My problem is that ocamlc and ocamlopt apear to be refusing to find third party libraries installed through apt-get. I first started having this problem when I tried to incorporate third-party modules into my own OCaml programs, and quickly wrote it off as a personal failing in understanding OCaml compilation. Soon-- however-- I found myself running into the same problem when trying to compile other peoples projects under their own instructions.
Here is the most straight-forward example. The others all use ocamlbuild, which obfuscates things a little bit.
The program: http://groups.google.com/group/fa.caml/msg/5aee553df34548e2
The compilation:
$ocamlc -g -dtypes -pp camlp4oof -I +camlp4 dynlink.cma camlp4lib.cma -cc g++ llvm.cma llvm_bitwriter.cma minml.ml -o minml
File "minml.ml", line 43, characters 0-9:
Error:Unbound module Llvm
Even when I provide ocamlc with the obsolute paths to the llvm files, like so...
$ ocamlc -g -dtypes -pp camlp4oof -I +camlp4 dynlink.cma camlp4lib.cma -cc g++ /usr/lib/ocaml/llvm-2.7/llvm.cma /usr/lib/ocaml/llvm-2.7/llvm_bitwriter.cma minml.ml -o minml
... to no avail.
What am I doing wrong?
Your command is doing two things: it's compiling minml.ml (into minml.cmo), then linking the resulting object into minml.
Compiling a module requires the interfaces of the dependencies. The interfaces contain typing information that is necessary to both the type checker and the code generator; this information is not repeated in the implementation (.cma here). So for the compilation stage, llvm.cmi must be available. The compiler looks for it in the include path, so you need an additional -I +llvm-2.7 (which is short for -I /usr/lib/ocaml/llvm-2.7).
The linking stage requires llvm.cma, which contains the bytecode implementation of the module. Here, you can either use -I or give a full path to let ocamlc know where to find the file.
ocamlc -g -dtypes -I +camlp4 -I +llvm-2.7 -pp camlp4oof -c minml.ml
ocamlc -g -cc g++ -I +camlp4 -I +llvm-2.7 dynlink.cma camlp4lib.cma llvm.cma llvm_bitwriter.cma minml.cmo -o minml
or if you want to do both stages in a single command:
ocamlc -g -dtypes -cc g++ -I +camlp4 -I +llvm-2.7 dynlink.cma camlp4lib.cma llvm.cma llvm_bitwriter.cma -pp camlp4oof minml.ml -o minml