需要调用命令行来执行某些命令，主要是用 subprocess 实时获取结果和捕获错误，发现subprocess的很多坑。

subprocess 普通获取结果方式，其需要命令完全执行才能返回结果：

import subprocess

scheduler_order = "df -h"

return_info = subprocess.Popen(scheduler_order, shell=True, stdout=subprocess.PIPE,stderr=subprocess.STDOUT)

for next_line in return_info.stdout:

    return_line = next_line.decode("utf-8", "ignore")

    print(return_line)

客subprocess 实时获取结果：

import subprocess

scheduler_order = "df -h"

return_info = subprocess.Popen(scheduler_order, shell=True, stdout=subprocess.PIPE,stderr=subprocess.STDOUT)

while True:

    next_line = return_info.stdout.readline()

    return_line = next_line.decode("utf-8", "ignore")

    if return_line == '' and return_info.poll() != None:

        break

    print(return_line)

想要获取报错机制，使用 check_output 捕捉报错和使用 check_call 捕捉报错，及时在 Popen 中捕获报错，都会使 实时输出失效 ！，所以自行查看 CalledProcessError 源码终于搞定。

实时发送以及捕获报错：

import subprocess

try:

    scheduler_order = "top -u ybtao"

    return_info = subprocess.Popen(scheduler_order, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)

    while True:

        next_line = return_info.stdout.readline()

        return_line = next_line.decode("utf-8", "ignore")

        if return_line == '' and return_info.poll() != None:

            break

        print(return_line)

    returncode = return_info.wait()

    if returncode:

        raise subprocess.CalledProcessError(returncode, return_info)

except Exception as e:

    print(e)