我遇到了一个问题，我认为该问题与重定向输出(运算符 >)和 os.system 工作方式的低级别有关
问题
这是我的代码。我想获取一堆文本文件的最后 2 行。它工作正常，但输出的组织方式让我感到困惑
import os
# Get list directory within the root directory
root_list_dir = [directory for directory in os.listdir(".") if os.path.isdir(directory)]
for directory in root_list_dir:
log_path = directory + "/acoustic_model/log/"
log_list = os.listdir(log_path)
for i in log_list:
print("==============================")
os.system("tail -n 2 " + log_path + "" + i)
当我调用python my_script.py时的标准输出(它按照我的预期工作。我切断了大部分输出，因为它是多余的):
==============================
2018-03-09 00:06:46,594 INFO main: Develop: DNN -- MCD: 4.891 dB; BAP: 0.185 dB; F0:- RMSE: 26.193 Hz; CORR: 0.794; VUV: 6.372%
2018-03-09 00:06:46,594 INFO main: Test : DNN -- MCD: 4.721 dB; BAP: 0.163 dB; F0:- RMSE: 22.119 Hz; CORR: 0.828; VUV: 6.052%
==============================
2018-03-23 17:08:31,564 INFO labels: loaded /data/thinhnv20/merlin-master/egs/build_your_own_voice/s1/experiments/doanngocle_cutaudio_3k5/test_synthesis/gen-lab/TTS8.lab, 84552 labels
2018-03-23 17:08:32,276 INFO labels: loaded /data/thinhnv20/merlin-master/egs/build_your_own_voice/s1/experiments/doanngocle_cutaudio_3k5/test_synthesis/gen-lab/TTS7.lab, 82456 labels
==============================
2018-05-18 21:05:26,605 INFO main: reconstructing waveform(s)
2018-05-18 21:05:26,605 INFO wav_generation: creating waveform for 1 of 1: labspit1
==============================
2018-05-18 21:57:58,600 INFO wav_generation: creating waveform for 1 of 2: labspit1
2018-05-18 21:58:25,779 INFO wav_generation: creating waveform for 2 of 2: labspit2
==============================
2018-05-05 03:06:25,523 INFO main: Develop: DNN -- MCD: 4.981 dB; BAP: 0.187 dB; F0:- RMSE: 27.926 Hz; CORR: 0.766; VUV: 6.610%
2018-05-05 03:06:25,524 INFO main: Test : DNN -- MCD: 4.832 dB; BAP: 0.166 dB; F0:- RMSE: 23.796 Hz; CORR: 0.797; VUV: 6.385%
==============================
2018-05-18 22:04:01,253 INFO wav_generation: creating waveform for 2 of 3: labspit1
2018-05-18 22:04:28,330 INFO wav_generation: creating waveform for 3 of 3: labspit2
==============================
2018-03-10 20:50:44,003 INFO main: Develop: DNN -- MCD: 4.892 dB; BAP: 0.182 dB; F0:- RMSE: 26.413 Hz; CORR: 0.790; VUV: 6.383%
2018-03-10 20:50:44,003 INFO main: Test : DNN -- MCD: 4.717 dB; BAP: 0.161 dB; F0:- RMSE: 21.953 Hz; CORR: 0.832; VUV: 6.134%
==============================
2018-03-13 09:23:05,873 INFO wav_generation: creating waveform for 31 of 32: TTS8
2018-03-13 09:23:08,908 INFO wav_generation: creating waveform for 32 of 32: TTS9
但是当我将输出重定向到文件时(通过调用 python my_script.py > results)，=============== 部分始终打印在结果的末尾:
2018-03-13 14:57:24,852 INFO wav_generation: creating waveform for 31 of 32: TTS8
2018-03-13 14:57:27,999 INFO wav_generation: creating waveform for 32 of 32: TTS9
2018-03-13 15:09:45,300 INFO wav_generation: creating waveform for 31 of 32: TTS8
2018-03-13 15:09:48,499 INFO wav_generation: creating waveform for 32 of 32: TTS9
2018-03-13 14:25:32,699 INFO main: Develop: DNN -- MCD: 4.875 dB; BAP: 0.183 dB; F0:- RMSE: 26.291 Hz; CORR: 0.792; VUV: 6.487%
2018-03-13 14:25:32,700 INFO main: Test : DNN -- MCD: 4.716 dB; BAP: 0.162 dB; F0:- RMSE: 22.129 Hz; CORR: 0.830; VUV: 6.132%
==============================
==============================
==============================
==============================
==============================
==============================
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==============================
==============================
谁能向我解释一下这里有什么问题吗？我很想听听任何信息! 提前致谢
最佳答案
您有两件事正在写入标准输出，两者都有自己的缓冲区。
这是您通常不想使用 os.system 的众多原因之一。
您可以强制 Python 在每个 print 之后刷新它的输出。只需使用flush=True参数即可。或者您甚至可以open(sys.stdout.fileno(), 'wb', buffering=0)，然后写入您自己的字节到禁用缓冲。
但这可能足够，也可能不够，因为您仍然无法控制 os.system 写入的内容。如果你想确保它的输出是无缓冲的，或者与 Python 共享相同的缓冲区，除了使用 subprocess 之外没有办法解决这个问题。 。正如 os.system 的文档首先所说的那样。
所以:
for i in log_list:
print("==============================")
proc = subprocess.run(['tail', '-n', '2', log_path + i], stdout=subprocess.PIPE)
print(proc.stdout)
关于python - 将输出重定向到文件时(使用 os.system 时)奇怪的 python 行为，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/50920618/