How to add a static library to my own static library

gmsa · 03-31-2010, 06:59 AM

To create a static library, or to add additional object files to an existing static library, I can use a command like this:

ar rcs my_library.a file1.o file2.o

But how to add an existing static library to my own static library.

I have created my own static library using the command above and want to link against the library libuuid.a (placed in /usr/lib/).

Can I use ar to add libuuid.a to my_library.a?

Sergei Steshenko · 03-31-2010, 07:01 AM

Quote:

Originally Posted by gmsa

To create a static library, or to add additional object files to an existing static library, I can use a command like this:

ar rcs my_library.a file1.o file2.o

But how to add an existing static library to my own static library.

I have created my own static library using the command above and want to link against the library libuuid.a (placed in /usr/lib/).

Can I use ar to add libuuid.a to my_library.a?

Why do you think you need to add one library to the other in the first place ?

wje_lq · 03-31-2010, 07:41 AM

Quote:

Originally Posted by gmsa

Can I use ar to add libuuid.a to my_library.a?

Yes. Use ar to list the elements of libuuid.a. Then, in a loop, extract each element from libuuid.a into a separate file and add that file to the end of my_library.a.

gmsa · 03-31-2010, 07:51 AM

Quote:

Originally Posted by Sergei Steshenko

Why do you think you need to add one library to the other in the first place ?

I have a static library (my_library.a) and in one of its header files I have included <uuid/uuid.h> to be able to use functions like 'uuid_generate'.

When I compile it, I get following error:
> undefined reference to `uuid_generate'

That's why I wanted to link libuuid.a to my own static library.
Is there any other way to resolve this problem?

Sergei Steshenko · 03-31-2010, 08:07 AM

Quote:

Originally Posted by gmsa

I have a static library (my_library.a) and in one of its header files I have included <uuid/uuid.h> to be able to use functions like 'uuid_generate'.

When I compile it, I get following error:
> undefined reference to `uuid_generate'

That's why I wanted to link libuuid.a to my own static library.
Is there any other way to resolve this problem?

Linux linker (which is implicitly called by 'gcc') allows as many libraries to be linked against as one wishes. Care should be taken of:

linker search paths (see the '-L' switch);
library order.

Linker can also be told to rescan libraries as needed - this increases link time, but eliminates the need of strict library order.

Read

man ld

, but it requires patience.

gmsa · 03-31-2010, 08:25 AM

Quote:

Originally Posted by wje_lq

Yes. Use ar to list the elements of libuuid.a. Then, in a loop, extract each element from libuuid.a into a separate file and add that file to the end of my_library.a.

I have listed the object files of libuuid.a:

> ar t /usr/lib/libuuid.a
clear.o
compare.o
copy.o
gen_uuid.o
isnull.o
pack.o
parse.o
unpack.o
unparse.o
uuid_time.o

How to extract those object files from the library?

Sergei Steshenko · 03-31-2010, 08:33 AM

Quote:

Originally Posted by gmsa

I have listed the object files of libuuid.a:

> ar t /usr/lib/libuuid.a
clear.o
compare.o
copy.o
gen_uuid.o
isnull.o
pack.o
parse.o
unpack.o
unparse.o
uuid_time.o

How to extract those object files from the library?

See in

man 1 ar

the 'x' command. But you do not need to extract.