Details and simple examples of python getopt

python getopt,

Function prototype:

getopt.getopt(args, shortopts, longopts=[])

Parameter explanation:

args: args is a list of parameters that need to be parsed. Use sys.argv [1:] to filter out the first parameter (ps: the first parameter is the name of the script and should not be parsed as a parameter) shortopts: shorthand parameter list longopts: long parameter list

The return value:

opts: the parsed (option, value) list pair. args: list of remaining command-line arguments that are not part of the format information.

Source code analysis

In the build system where Android generates OTA, the ParseOptions function in the common.py file is used to parse the input parameters. We will analyze the use of getopt 1 through the implementation of this function.

The source code of the function is as follows:

def ParseOptions(argv, docstring, extra_opts="", extra_long_opts=(), extra_option_handler=None):
  try:
    opts, args = getopt.getopt(
      argv, "hvp:s:x" + extra_opts,
      ["help", "verbose", "path=", "signapk_path=", "extra_signapk_args=", "java_path=", "public_key_suffix=", "private_key_suffix=", "device_specific=", "extra="] + list(extra_long_opts))
  except getopt.GetoptError, err:
    Usage(docstring)
    print "**", str(err), "**"
    sys.exit(2)

  path_specified = False

  for o, a in opts:
    if o in ("-h", "--help"):
      Usage(docstring)
      sys.exit()
    elif o in ("-v", "--verbose"):
      OPTIONS.verbose = True
    elif o in ("-p", "--path"):
      OPTIONS.search_path = a
    elif o in ("--signapk_path",):
      OPTIONS.signapk_path = a
    elif o in ("--extra_singapk_args",):
      OPTIONS.extra_signapk_args = shlex.split(a)
    elif o in ("--java_path",):
      OPTIONS.java_path = a
    else:
      if extra_option_handler is None or not extra_option_handler(o, a):
      assert False, "unknown option \"%s\"" % (o,)

  os.environ["PATH"] = (os.path.join(OPTIONS.search_path, "bin") + os.pathsep + os.environ["PATH"])

  return args

Where, extra_option_handler can be understood as a function pointer, and its function is also to parse opts's key-value pairs.

The source code of extra_option_handler is as follows:

 def option_handler(o, a):
  if o in ("-b", "--board_config"):
   pass  # deprecated
  elif o in ("-k", "--package_key"):
   OPTIONS.package_key = a
  elif o in ("-i", "--incremental_from"):
   OPTIONS.incremental_source = a
  elif o in ("-w", "--wipe_user_data"):
   OPTIONS.wipe_user_data = True
  elif o in ("-n", "--no_prereq"):
   OPTIONS.omit_prereq = True
  elif o in ("-e", "--extra_script"):
   OPTIONS.extra_script = a
  elif o in ("-a", "--aslr_mode"):
   if a in ("on", "On", "true", "True", "yes", "Yes"):
    OPTIONS.aslr_mode = True
   else:
    OPTIONS.aslr_mode = False
  elif o in ("--worker_threads"):
   OPTIONS.worker_threads = int(a)
  else:
   return False
  return True

The parameter argv to generate OAT full package is as follows:

argv = ['-v', '-p', 'out/host/linux-xxx', '-k', 'build/target/product/security/testkey',
 'out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip', 
'out/target/product/xxx/xxx_20150723.1340-ota.zip']

First, the parameters are analyzed, among which the short parameters include:

-v,-p,-k,

After parsing, the results are as follows:

opts = [('-v', ''), ('-p', 'out/host/linux-x86'), 
('-k', 'build/target/product/security/testkey')]
args =['out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip',
 'out/target/product/xxx/xxx_20150723.1340-ota.zip']

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