How to embed version information into shared library and binary?

Question

On Linux, is there a way to embed version information into an ELF binary? I would like to embed this info at compile time so it can then be extract it using a script later. A hackish way would be to plant something that can be extracted using the strings command. Is there a more conventional method, similar to how Visual Studio plant version info for Windows DLLs (note version tab in DLL properties)?

Answer 1

One way to do it if using cvs or subversion is to have a special id string formatted specially in your source file. Then add a pre-commit hook to cvs or svn that updates that special variable with the new version of the file when a change is committed. Then, when the binary is built, you can use ident to extract that indformation. For example:

Add something like this to your cpp file:

static char fileid[] = "$Id: fname.cc,v 1.124 2010/07/21 06:38:45 author Exp $";

And running ident (which you can find by installing rcs) on the program should show the info about the files that have an id string in them.

ident program
program:
    $Id: fname.cc,v 1.124 2010/07/21 06:38:45 author Exp $

Note As people have mentioned in the comments this technique is archaic. Having the source control system automatically change your source code is ugly and the fact that source control has improved since the days when cvs was the only option means that you can find a better way to achieve the same goals.