Thread: How do I make shared libs on Linux?

Hi,
I'm building static and shared libs (.a & .sl) with these make options:

Code:

SHLIB=libname.sl
CC=cc
AR=ld
ARFLAGS=-Bdynamic -shared -warn-common -warn-constructors -warn-multiple-gp -warn-once -o
INC=../src
DEFS=-DPOSIX -DANSI
CFLAGS=-Wall -Wno-unused -fpic -shared -I. -I$(INC) $(DEFS)

$(SHLIB): $(OBJS)
	rm -f $(SHLIB)
	$(AR) $(ARFLAGS) $(SHLIB) $(OBJS)

debug.o: $(SRC)/debug.c $(HEADERS)
	$(CC) -c $(CFLAGS) $(SRC)/debug.c
...

But after I build my test program and run it, I get a segmentation fault. The program works fine with the static libs.

On Solaris, the LD_LIBRARY_PATH environment variable is used to specify where the shared libs are. As far as I can tell, Linux uses LIBRARY_PATH. Is that right, or do I need something else?

Do I need any other link options, or should I get rid of any that I have...?

This is how my test program is built:

Code:

CC=cc
CFLAGS=-Wall -DPOSIX -DANSI
SHLIBS=-L$$SHLIB_PATH

ivpslibs: scp.o rproc.o sstubs.o smain.o
	$(CC) -shared -o ivpslibs scp.o rproc.o sstubs.o smain.o $(SHLIBS)

sstubs.o: sstubs.c ivp.h
	$(CC) $(CFLAGS) -c $(INCS) sstubs.c
...

I don't know if it's a problem with how I build the shared lib or the test program or both?

Originally Posted by cpjust

On Solaris, the LD_LIBRARY_PATH environment variable is used to specify where the shared libs are. As far as I can tell, Linux uses LIBRARY_PATH. Is that right, or do I need something else?

No, it is also LD_LIBRARY_PATH.

You don't need "-shared" in your CFLAGS. Also, why name the library with .sl instead of .so? The dynamic linker is probably confused by that.

Originally Posted by matsp

You do not create shared libraries with "ar" - you create them with gcc or ld - I'm not quite sure about which switches you throw to make it create a .so file [which is the correct name, by the way].

He IS using ld, he just sticks it in a variable called $(AR). I thought it was weird but didn't say anything.

OK thanks, I'll try those suggestions.

The .sl looked weird to me too. I ported this makefile from HPUX...