For the record, normal start-up happens like this (simplified): 1. prep for and create/initialize interpreter 2. exec the site module in the __main__ namespace (unless -S) 3. do the interface-specific stuff Note: exec of the site module does not impact the spec. In the case where -i/PYTHONINSPECT is issued (or implied): 1. ... 2. ... 3. exec the PYTHONSTARTUP script (if set and it exists) 4. do the interface-specific stuff 5. start the REPL Note: the -i case does not impact the spec, nor does the exec of any PYTHONSTARTUP script. See: [1] http://docs.python.org/3.4/using/cmdline.html [2] Python/pythonrun.c [3] Modules/main.c [4] PEP 432