使用 awk 和管道的 Python 子进程

Question

我的 Python 脚本中有以下语句:

year = '1966'
file = 'test.txt'
cmd = "awk '{FS="|"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc" % (year, file)
bla = run_command(cmd)

其中 fun_command() 是函数:

def run_command(command):                                     
  process = subprocess.Popen([sys.executable, command], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  retcode = process.wait()
  if retcode != 0:
    raise Exception, "Problem running command: " + command
  stdout, stderr = process.communicate()
  return stdout

产生以下输出:

TypeError: unsupported operand type(s) for |: 'str' and 'str'

有什么问题吗？

Answer 1

"awk '{FS="|"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc"
这里需要转义内部 "|"

"awk '{FS=\"|\"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc"