OT: Linux shared lib question

Bill Baxter dnewsgroup at billbaxter.com
Mon May 12 16:57:05 PDT 2008

Not really a D question, but I'm hoping someone out there knows the 
answer (it is for the purpose of getting my D Multiarray library working 
better on Linux, though.)

I want to create a shared .so from a .a library.

I found on a web page somewhere that a .so can be created from some .o 
files using something like the following:

   gcc -shared -Wl,-soname,lib${name}.so.1 -o lib${name}.so.1.1 \
       a.o b.o c.o

So I figured if it can do that then surely this would work:

   gcc -shared -Wl,-soname,lib${name}.so.1 -o lib${name}.so.1.1 \

where libmylibrary.a is a lib containing a.o, b.o, and c.o.  After all a 
.a archive is basically just a concatenation of .o files in a convenient 

However, though the command runs without reporting an error, the 
resulting .so does not contain the contents of libmylibrary.a.

SO what I'm doing now in my "make .so from .a" script is basically this:
     mkdir tmp
     cd tmp
     ar x path/to/libmylibrary.a
     gcc -shared -Wl,-soname,libfoo.so.1 -o libfoo.so.1.1  *.o
     rm *.o
     cd ..
     rmdir tmp

Extract the .o's from the .a, make the shared lib using that, then clean 

Is that really the best way to do this?  With MinGW you can directly 
create a dll from a .a, so I was a bit surprised to find out that the 
same gcc flags do not work on Linux to create a .so.  Is this a case 
where the Windows version of a GNU tool is actually easier to use than 
the Linux version?


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