python延迟命令如何处理依赖关系

在Python中，处理依赖关系的一种方法是使用subprocess模块来执行命令

import subprocess
import time

def run_command(command):
    process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    stdout, stderr = process.communicate()
    return process.returncode, stdout, stderr

def main():
    command1 = "echo 'Command 1 is running...'"
    command2 = "sleep 3 && echo 'Command 2 is running...'"

    # Run command1
    print(f"Running {command1}")
    exit_code1, stdout1, stderr1 = run_command(command1)
    if exit_code1 != 0:
        print(f"Error in command1: {stderr1.decode('utf-8')}")
    else:
        print(f"Success in command1: {stdout1.decode('utf-8')}")

    # Wait for command1 to finish
    time.sleep(1)

    # Run command2 with dependency on command1
    print(f"Running {command2}")
    exit_code2, stdout2, stderr2 = run_command(command2)
    if exit_code2 != 0:
        print(f"Error in command2: {stderr2.decode('utf-8')}")
    else:
        print(f"Success in command2: {stdout2.decode('utf-8')}")

if __name__ == "__main__":
    main()

在这个示例中，我们定义了一个run_command函数来执行给定的命令，并返回进程的退出代码、标准输出和标准错误。在main函数中，我们首先运行command1，然后等待1秒钟以确保command1已完成。接下来，我们运行command2，它依赖于command1的完成。如果command2执行成功，我们将看到以下输出：

Running Command 1 is running...
Success in command1: Command 1 is running...
Running Command 2 is running...
Success in command2: Command 2 is running...

请注意，这个示例中的依赖关系很简单，只是等待1秒钟。在实际应用中，你可能需要使用更复杂的方法来处理依赖关系，例如使用锁文件、信号量或其他同步机制。