1. python which OS are we running on (os, platform)
  2. Current directory (getcwd, pwd, chdir)
  3. OS path
  4. os.path.join
  5. Directory listing
  6. Directory listing using glob
  7. Traverse directory tree - list directories recursively
  8. OS dir (mkdir, makedirs, remove, rmdir)
  9. expanduser - handle tilde ~ the home directory of the user
  10. Get process ID
  11. External command with system
  12. Accessing the system environment variables from Python
  13. Set env and run command