Having updated to Debian 7.0, my normal cycle of keeping things up-to-date with aptitude suggested that I install linux-libc-dev. When I tried to install, things broke saying:
" warning: 'ldconfig' not found in PATH or not executable"
Google initially sent me down the wrong path to a solution to a slightly different problem on the Ubuntu forums.
Taking a moment to actually read the error message, the fix was a simple addition of /sbin and /usr/sbin to my path. Quite a nice write up of the issue is here.
What I can't explain is why Debian 7.0 removed the sbin directories from my PATH. It seems to have done it on all the Debian servers I look after. I can't find any reference to this on the internet.