Python subprocess shell 编程规范

　　使用subprocess通过shell调用另一个模块组件时，需要对返回的code进行判断。判断结果为执行失败时需要raise Exception，不然调用树过于复杂时，我们很难跟踪到异常发生的位置。sys.exit(1)虽然也可以达到对执行结果进行判断的目的，但是它难于追踪异常发生的位置。

1 a.py
2 `-- b.py
3     `-- ls

a.py

 1 import sys, subprocess
 2 
 3 def exec_cmd(cmd):
 4     """Run shell command"""
 5     p = subprocess.Popen(cmd,stdin = subprocess.PIPE, \
 6         stdout = subprocess.PIPE,
 7         stderr = subprocess.STDOUT,
 8         shell = True)
 9 
10     log_content = p.communicate()[0]
11 
12     return p.returncode, log_content
13 
14 def main():
15     cmd = "python b.py"
16     cmd_code, cmd_log = exec_cmd(cmd)
17     if not cmd_code == 0:
18         raise Exception(cmd_log)
19 
20 if __name__ == '__main__':
21     main()

b.py

 1 import sys, subprocess
 2 
 3 def exec_cmd(cmd):
 4     """Run shell command"""
 5     p = subprocess.Popen(cmd,stdin = subprocess.PIPE, \
 6         stdout = subprocess.PIPE,
 7         stderr = subprocess.STDOUT,
 8         shell = True)
 9 
10     log_content = p.communicate()[0]
11 
12     return p.returncode, log_content
13 
14 def main():
15     cmd = """ls c.py"""
16     cmd_code, cmd_log = exec_cmd(cmd)
17     if not cmd_code == 0:
18         raise Exception(cmd_log)
19 
20 if __name__ == '__main__':
21     main()

运行结果：

 1 waterforestdeiMac:pythonCrawler waterforest$ python a.py 
 2 Traceback (most recent call last):
 3   File "a.py", line 21, in <module>
 4     main()
 5   File "a.py", line 18, in main
 6     raise Exception(cmd_log)
 7 Exception: Traceback (most recent call last):
 8   File "b.py", line 21, in <module>
 9     main()
10   File "b.py", line 18, in main
11     raise Exception(cmd_log)
12 Exception: ls: c.py: No such file or directory
13 
14 
15 waterforestdeiMac:pythonCrawler waterforest$

 

posted @ 2017-03-29 20:01  天~宇~翱~翔  阅读(328)  评论(0)  编辑  收藏  举报