At my work, we have (all in-house and most are more than twenty years old):

  - A (much more complicated) make clone
  - A test running framework
  - A remote session tool
  - A test specification framework
  - A preprocessing tool
  - At least six domain-specific languages for specifying compilers, assemblers, linkers, simulators.

Of course, you also need to know Linux, bash, C, C++, Perl, and Python.

Needless to say, it takes some time to get up to speed. On the other hand, you can run some very simple commands and have a bunch of servers run hundreds of thousands of tests on your code, on different OSes.