The difference between .a and .so library files

Harry Seldon · 12-14-2007, 09:48 AM

I'm trying to install netpbm and I need the jpeg functionality. During the install, I'm being asked for my jpeg library file, which defaults to libjpeg.so. I installed the libjpeg-6b-6 rpm package and now I have a libjpeg.a file but no .so. I'm not sure I understand the difference between the two file types. Can libjpeg.a be used as a substitute or equivalent to libjpeg.so?

jschiwal · 12-14-2007, 09:52 AM

Install the "libjpeg" package for the .so libraries. You installed the "libjpeg-devel" package.

nirvana4ol · 12-14-2007, 09:56 AM

Libraries ending in '.a' are static libraries and in '.so' are shared. More info can be found here.

http://www.dwheeler.com/program-libr...WTO/index.html

Harry Seldon · 12-14-2007, 10:09 AM

I had the libjpeg package installed already so I tried installing the development package but still don't have the .so file. Here's what I see:

# find /opt -name libjpeg*
/opt/freeware/lib/libjpeg.a
/opt/freeware/doc/libjpeg-6b
/opt/freeware/doc/libjpeg-devel-6b
/opt/freeware/doc/libjpeg-devel-6b/libjpeg.doc
/opt/freeware/64/lib/libjpeg.a
# find /usr -name libjpeg*
/usr/lib/libjpeg.a
/usr/java14/jre/bin/libjpeg.a
/usr/xlhelp/jre/bin/libjpeg.a
# rpm -qa | grep libjpeg
libjpeg-6b-6
libjpeg-devel-6b-6

Harry Seldon · 12-14-2007, 10:11 AM

@nirvana4ol

Does that mean I can point the netpbm install at the static library instead? The linked page on static libraries seems to point in that direction. Maybe I'll just try it and see if my gmake completes successfully.

Junior Hacker · 12-14-2007, 09:11 PM

If you were to copy and paste "libjpeg.so" from your post into the .rpm search engine here, you would find that SUSE requires java to be installed. Look on page 8 & 9 of the search results when doing a standard (not Advanced) search.