how to differentiate static library/compilation with dynamic?

[esolve]

I want to compile a program with two libraries: lpcap and levent

but it seems to me that the commands for static compilation and dynamic compilation are the same


gcc -o myprogram main.c -lpcap -levent


if I want to make sure it is static compilation, how?
and how can I determine whether the lpcap and levent are static library or dynamic library?

I notice there are four libpcap library files,
how to determine which one is used?
especially there are 3 versions of libpcap.so, which one is used if I run the above command.

/usr/lib/x86_64-linux-gnu/libpcap.a
/usr/lib/x86_64-linux-gnu/libpcap.so
/usr/lib/x86_64-linux-gnu/libpcap.so.0.8
/usr/lib/x86_64-linux-gnu/libpcap.so.1.5.3

[Duthomhas]

gcc -o myprogram main.c -static -lpcap -levent

[andywestken]

Is libpcap.so not a symlink? (I would expect it to be symlink to libpcap.so.1.5.3, as it's the newest version.)

Without -static you'll link to whatever the symlink libpcap.so rerers to. With -static you link to libpcap.a

Andy

GNU linker manual
https://sourceware.org/binutils/docs-2.21/ld/

On systems which support shared libraries, ld may also search for files other than libnamespec.a. Specifically, on ELF and SunOS systems, ld will search a directory for a library called libnamespec.so before searching for one called libnamespec.a. (By convention, a .so extension indicates a shared library.) Note that this behavior does not apply to :filename, which always specifies a file called filename

[andywestken]

PS (Aimed at my future self, as much as anyone else...)

In the MinGW and CYGWIN cases, the search order is more confusing it seems:

libxxx.dll.a
xxx.dll.a
libxxx.a
cygxxx.dll (*)
libxxx.dll
xxx.dll

ld and WIN32 (cygwin/mingw)
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/4/html/Using_ld_the_GNU_Linker/win32.html

Incidentally, this article also provides the answer to a question asked in this thread:

Am I understanding dll and lib files right?
http://www.cplusplus.com/forum/general/164929/

yj1214 wrote:

Game libraries such as Irrlicht don't requires to link with lib files. You can just link directly with dll file.

The answer being:

The cygwin/mingw ports of ld support the direct linking, including data symbols, to a dll without the usage of any import libraries.

Andy