Turning Red Hat 7.1 into Debian testing: one bit at a time

First, upgrade libc from 2.2.2 to 2.3.6: most old binaries worked
Warning: statically built binaries will dlopen old libc libraries directly (libnss) and fail if you upgrade libc without compat symlinks or rebuilding the static binaries.
Start with easy packages like 'ed' and 'bc' and work your way up.
A few binaries had warnings on stderr, we then rebuilt/upgraded them first):

First, upgrade libc from 2.2.2 to 2.3.6: most old binaries worked