Programming

I've compiled quite a bit of code on AIX and I am familiar with linking in libraries (/usr/lib/*.a). I've recently been tasked with porting some of the code to Linux...I've noticed there are some *.so files as well as *.a files in /usr/lib. Are these *.so files different from the *.a files? How are they linked/used?

Thanks in advance!!

Thanks for the document, Driver...I explains what the *.so files are & how to create them under AIX.

This is my scenario...I am porting Netview snmp polling daemons to Linux. The man pages for OVsnmpRead( ) (a Netview function) say that libovsnmp.a, libov.a, and libntl.a libraries must be linked to compile. But....these files don't exist in Netview for Linux...just libovsnmp.so, libov.so, and libntl.so instead. I was able to compile the application while linking in these libs the same way as I did in AIX:

"-L /usr/OV/lib -lov -lovsnmp -lOVs -lnvot -ltdl -lutil -lntl"


I found the ldd command and when I apply it to my application, I get:

libov.so => /usr/lib/libov.so (0x40033000)
libovsnmp.so => /usr/lib/libovsnmp.so (0x4003f000)
libnvot.so => /usr/lib/libnvot.so (0x4005d000)
libutil.so.1 => /lib/libutil.so.1 (0x400a3000)
libntl.so => /usr/lib/libntl.so (0x400a6000)
libc.so.6 => /lib/i686/libc.so.6 (0x400b2000)
libnsl.so.1 => /lib/libnsl.so.1 (0x401ed000)
libdl.so.2 => /lib/libdl.so.2 (0x40204000)
libovw.so => /usr/lib/libovw.so (0x40208000)
libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x402d4000)
libXt.so.6 => /usr/X11R6/lib/libXt.so.6 (0x403b2000)
libXp.so.6 => /usr/X11R6/lib/libXp.so.6 (0x403fe000)
libXext.so.6 => /usr/X11R6/lib/libXext.so.6 (0x40406000)
libXmu.so.6 => /usr/X11R6/lib/libXmu.so.6 (0x40415000)
libcollection.so => /usr/lib/libcollection.so (0x4042b000)
libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x4044f000)
libems.so => /usr/lib/libems.so (0x40491000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
libSM.so.6 => /usr/X11R6/lib/libSM.so.6 (0x404df000)
libICE.so.6 => /usr/X11R6/lib/libICE.so.6 (0x404e8000)
libm.so.6 => /lib/i686/libm.so.6 (0x40500000)
libCMU.so => /usr/lib/libCMU.so (0x40523000)
libmib.so => /usr/lib/libmib.so (0x40557000)

Does this mean that the libs are linked?

Thanks!