如何抑制subprocess.run（）的輸出？

Question

從上subprocess.run()在文檔的例子，好像不應該有來自

subprocess.run(["ls", "-l"]) # doesn't capture output 

但是任何輸出，當我嘗試在Python殼上市被打印出來。我想知道這是否是默認行爲，以及如何抑制run()的輸出。

Answer 1

要抑制輸出，你可以，如果你想捕獲輸出（以供以後使用或分析）重定向到/dev/null

import os 
import subprocess 

with open(os.devnull, 'w') as devnull: 
    subprocess.run(['ls', '-l'], stdout=devnull) 
    # The above only redirects stdout... 
    # this will also redirect stderr to /dev/null as well 
    subprocess.run(['ls', '-l'], stdout=devnull, stderr=devnull) 
    # Alternatively, you can merge stderr and stdout streams and redirect 
    # the one stream to /dev/null 
    subprocess.run(['ls', '-l'], stdout=devnull, stderr=subprocess.STDOUT) 

，你需要使用subprocess.PIPE

import subprocess 
result = subprocess.run(['ls', '-l'], stdout=subprocess.PIPE) 
print(result.stdout) 

# To also capture stderr... 
result = subprocess.run(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.PIPE) 
print(result.stdout) 
print(result.stderr) 

# To mix stdout and stderr into a single string 
result = subprocess.run(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT) 
print(result.stdout)