python - python 子进程中的 watch 命令仅打印输出中的更改

Question

我确实使用 python subprocess 模块来获取 kubernetes 应用程序的状态，如下所示:

command = gravity status | grep -o 'Cluster status:.*' | cut -f2- -d:

def run_cmd(command):
    process  = subprocess.Popen(command,shell=True, universal_newlines=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = process.communicate()
    return out, err;

out: active

确实生成输出“active”或“degraded”，但我想实现一个“watch”，因此仅当将“active”更改为“degraded”时才会打印 和 'degraded' to 'active' 不要每隔几分钟运行一次来​​向我提供状态。

Question: how I can do this in python as a script or it is possible ?

Answer 1

试试这个方法

a=1
while a==1:
        out = subprocess.Popen('date', 
stdout=subprocess.PIPE).communicate()[0]
        time.sleep(2)
        out2 = subprocess.Popen('date', 
stdout=subprocess.PIPE).communicate()[0]
        if out != out2:
                print (out)