python getopt知识介绍

python getopt知识介绍

python getopt详解

函数原型:

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

参数解释:

  • args:args为需要解析的参数列表。一般使用sys.argv[1:],这样可以过滤掉第一个参数(ps:第一个参数是脚本的名称,它不应该作为参数进行解析)
  • shortopts:简写参数列表
  • longopts:长参数列表

返回值:

  • opts:分析出的(option, value)列表对。
  • args:不属于格式信息的剩余命令行参数列表。

源码分析

在Android生成OTA的build系统中,common.py文件中的ParseOptions函数就是用来解析输入参数的,我们来通过该函数的实现来分析一下getopt的使用。

函数源码如下:

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

其中,extra_option_handler可以理解为函数指针,它的功能也是解析opts的键值对。

extra_option_handler源码如下:

 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

一般生成OAT全量包的参数argv如下:

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']

首先,对参数进行分析,其中短参数包括:

-v,-p,-k,

经过解析后,生成的结果如下所示:

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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