Multiple glibc libraries on a single host
This question is old, the other answers are old. "Employed Russian"s answer is very good and informative, but it only works if you have the source code. If you don't, the alternatives back then were very tricky. Fortunately nowadays we have a simple solution to this problem (as commented in one of his replies), using patchelf. All you have to do is:
$ ./patchelf --set-interpreter /path/to/newglibc/ld-linux.so.2 --set-rpath /path/to/newglibc/ myapp
And after that, you can just execute your file:
$ ./myapp
No need to chroot or manually edit binaries, thankfully. But remember to backup your binary before patching it, if you're not sure what you're doing, because it modifies your binary file. After you patch it, you can't restore the old path to interpreter/rpath. If it doesn't work, you'll have to keep patching it until you find the path that will actually work... Well, it doesn't have to be a trial-and-error process. For example, in OP's example, he needed GLIBC_2.3, so you can easily find which lib provides that version using strings:
$ strings /lib/i686/libc.so.6 | grep GLIBC_2.3
$ strings /path/to/newglib/libc.so.6 | grep GLIBC_2.3
In theory, the first grep would come empty because the system libc doesn't have the version he wants, and the 2nd one should output GLIBC_2.3 because it has the version myapp is using, so we know we can patchelf our binary using that path. If you get a segmentation fault, read the note at the end.
When you try to run a binary in linux, the binary tries to load the linker, then the libraries, and they should all be in the path and/or in the right place. If your problem is with the linker and you want to find out which path your binary is looking for, you can find out with this command:
$ readelf -l myapp | grep interpreter
[Requesting program interpreter: /lib/ld-linux.so.2]
If your problem is with the libs, commands that will give you the libs being used are:
$ readelf -d myapp | grep Shared
$ ldd myapp
This will list the libs that your binary needs, but you probably already know the problematic ones, since they are already yielding errors as in OP's case.
"patchelf" works for many different problems that you may encounter while trying to run a program, related to these 2 problems. For example, if you get: ELF file OS ABI invalid, it may be fixed by setting a new loader (the --set-interpreter part of the command) as I explain here. Another example is for the problem of getting No such file or directory when you run a file that is there and executable, as exemplified here. In that particular case, OP was missing a link to the loader, but maybe in your case you don't have root access and can't create the link. Setting a new interpreter would solve your problem.
Thanks Employed Russian and Michael Pankov for the insight and solution!
Note for segmentation fault: you might be in the case where myapp uses several libs, and most of them are ok but some are not; then you patchelf it to a new dir, and you get segmentation fault. When you patchelf your binary, you change the path of several libs, even if some were originally in a different path. Take a look at my example below:
$ ldd myapp
./myapp: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.20' not found (required by ./myapp)
./myapp: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by ./myapp)
linux-vdso.so.1 => (0x00007fffb167c000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f9a9aad2000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f9a9a8ce000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f9a9a6af000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f9a9a3ab000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9a99fe6000)
/lib64/ld-linux-x86-64.so.2 (0x00007f9a9adeb000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f9a99dcf000)
Note that most libs are in /lib/x86_64-linux-gnu/ but the problematic one (libstdc++.so.6) is on /usr/lib/x86_64-linux-gnu. After I patchelf'ed myapp to point to /path/to/mylibs, I got segmentation fault. For some reason, the libs are not totally compatible with the binary. Since myapp didn't complain about the original libs, I copied them from /lib/x86_64-linux-gnu/ to /path/to/mylibs2, and I also copied libstdc++.so.6 from /path/to/mylibs there. Then I patchelf'ed it to /path/to/mylibs2, and myapp works now. If your binary uses different libs, and you have different versions, it might happen that you can't fix your situation. :( But if it's possible, mixing libs might be the way. It's not ideal, but maybe it will work. Good luck!
Use LD_PRELOAD: put your library somewhere out of the man lib directories and run:
LD_PRELOAD='mylibc.so anotherlib.so' program
See: the Wikipedia article
First of all, the most important dependency of each dynamically linked program is the linker. All so libraries must match the version of the linker.
Let's take simple exaple: I have the newset ubuntu system where I run some program (in my case it is D compiler - ldc2). I'd like to run it on the old CentOS, but because of the older glibc library it is impossible. I got
ldc2-1.5.0-linux-x86_64/bin/ldc2: /lib64/libc.so.6: version `GLIBC_2.15' not found (required by ldc2-1.5.0-linux-x86_64/bin/ldc2)
ldc2-1.5.0-linux-x86_64/bin/ldc2: /lib64/libc.so.6: version `GLIBC_2.14' not found (required by ldc2-1.5.0-linux-x86_64/bin/ldc2)
I have to copy all dependencies from ubuntu to centos. The proper method is following:
First, let's check all dependencies:
ldd ldc2-1.5.0-linux-x86_64/bin/ldc2
linux-vdso.so.1 => (0x00007ffebad3f000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f965f597000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f965f378000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f965f15b000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f965ef57000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f965ec01000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f965e9ea000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f965e60a000)
/lib64/ld-linux-x86-64.so.2 (0x00007f965f79f000)
linux-vdso.so.1 is not a real library and we don't have to care about it.
/lib64/ld-linux-x86-64.so.2 is the linker, which is used by the linux do link the executable with all dynamic libraries.
Rest of the files are real libraries and all of them together with the linker must be copied somewhere in the centos.
Let's assume all the libraries and linker are in "/mylibs" directory.
ld-linux-x86-64.so.2 - as I've already said - is the linker. It's not dynamic library but static executable. You can run it and see that it even have some parameters, eg --library-path (I'll return to it).
On the linux, dynamically linked program may be lunched just by its name, eg
/bin/ldc2
Linux loads such program into RAM, and checks which linker is set for it. Usually, on 64-bit system, it is /lib64/ld-linux-x86-64.so.2 (in your filesystem it is symbolic link to the real executable). Then linux runs the linker and it loads dynamic libraries.
You can also change this a little and do such trick:
/mylibs/ld-linux-x86-64.so.2 /bin/ldc2
It is the method for forcing the linux to use specific linker.
And now we can return to the mentioned earlier parameter --library-path
/mylibs/ld-linux-x86-64.so.2 --library-path /mylibs /bin/ldc2
It will run ldc2 and load dynamic libraries from /mylibs.
This is the method to call the executable with choosen (not system default) libraries.
It is very possible to have multiple versions of glibc on the same system (we do that every day).
However, you need to know that glibc consists of many pieces (200+ shared libraries) which all must match. One of the pieces is ld-linux.so.2, and it must match libc.so.6, or you'll see the errors you are seeing.
The absolute path to ld-linux.so.2 is hard-coded into the executable at link time, and can not be easily changed after the link is done (Update: can be done with patchelf; see this answer below).
To build an executable that will work with the new glibc, do this:
g++ main.o -o myapp ... \
-Wl,--rpath=/path/to/newglibc \
-Wl,--dynamic-linker=/path/to/newglibc/ld-linux.so.2
The -rpath linker option will make the runtime loader search for libraries in /path/to/newglibc (so you wouldn't have to set LD_LIBRARY_PATH before running it), and the -dynamic-linker option will "bake" path to correct ld-linux.so.2 into the application.
If you can't relink the myapp application (e.g. because it is a third-party binary), not all is lost, but it gets trickier. One solution is to set a proper chroot environment for it. Another possibility is to use rtldi and a binary editor. Update: or you can use patchelf.