内容 隐藏
问题：Nohup没有将日志写入输出文件
回答 0
回答 1
回答 2
回答 3
回答 4
回答 5

问题：Nohup没有将日志写入输出文件

我正在使用以下命令在后台运行python脚本：

nohup ./cmd.py > cmd.log &

但是似乎nohup没有向日志文件写入任何内容。cmd.log已创建，但始终为空。在python脚本中，我使用sys.stdout.write而不是print打印到标准输出。我做错什么了吗？

点击查看英文原文

I am using the following command to run a python script in the background:

nohup ./cmd.py > cmd.log &

But it appears that nohup is not writing anything to the log file. cmd.log is created but is always empty. In the python script, I am using sys.stdout.write instead of print to print to standard output. Am I doing anything wrong?

回答 0

看来您需要定期刷新标准输出（例如sys.stdout.flush()）。在我的测试中，Python不会自动执行此操作，print直到程序退出。

点击查看英文原文

It looks like you need to flush stdout periodically (e.g. sys.stdout.flush()). In my testing Python doesn’t automatically do this even with print until the program exits.

回答 1

您可以使用带有-u标志的Python 来避免输出缓冲：

nohup python -u ./cmd.py > cmd.log &
点击查看英文原文

You can run Python with the -u flag to avoid output buffering:

nohup python -u ./cmd.py > cmd.log &

回答 2

  • 使用-u with nohup对我有用。使用-u将迫使stdout，stderr流是缓冲。它不会影响标准输入。一切都将保存在“ nohup.out ”文件中。像这样-

    nohup python -u your_code.py &

    您也可以将其保存到目录中。这条路-

    nohup python -u your_code.py > your_directory/nohup.out &

  • 另外，您可以使用PYTHONUNBUFFERED。如果将其设置为非空字符串，它将与该-u选项相同。要在运行python代码之前使用以下命令运行此命令。

    export PYTHONUNBUFFERED=1

    要么

    export PYTHONUNBUFFERED=TRUE

PS： 我建议使用cron-job之类的工具在后台运行程序并安排执行时间。

点击查看英文原文

  • Using -u with nohup worked for me. Using -u will force the stdout, stderr streams to be unbuffered. It will not affect stdin. Everything will be saved in “nohup.out ” file. Like this-

    nohup python -u your_code.py &

    You can also save it into your directory. This way- 

    nohup python -u your_code.py > your_directory/nohup.out &

  • Also, you can use PYTHONUNBUFFERED. If you set it to a non-empty string it will work same as the -u option. For using this run below commands before running python code.

    export PYTHONUNBUFFERED=1

    or

    export PYTHONUNBUFFERED=TRUE

P.S.- I will suggest using tools like cron-job to run things in the background and scheduled execution.

回答 3

export PYTHONUNBUFFERED=1
nohup ./cmd.py > cmd.log &

要么

nohup python -u ./cmd.py > cmd.log &

https://docs.python.org/2/using/cmdline.html#cmdoption-u

点击查看英文原文 
export PYTHONUNBUFFERED=1
nohup ./cmd.py > cmd.log &

or

nohup python -u ./cmd.py > cmd.log &

https://docs.python.org/2/using/cmdline.html#cmdoption-u

回答 4

Python 3.3及更高版本有一个flush参数用于打印，这是唯一对我有用的方法。

print("number to train = " + str(num_train), flush=True)
print("Using {} evaluation batches".format(num_evals), flush=True)
点击查看英文原文

Python 3.3 and above has a flush argument to print and this is the only method that worked for me.

print("number to train = " + str(num_train), flush=True)
print("Using {} evaluation batches".format(num_evals), flush=True)

回答 5

我有一个类似的问题，但未与Python进程关联。我正在运行一个脚本，该脚本执行了nohup，并且该脚本通过cron定期运行。

我可以通过以下方法解决问题：

  1. 重定向标准输入，标准输出和标准错误
  2. 确保通过nohup调用的脚本没有在后台运行其他任何东西

PS：我的脚本是用RHEL上运行的ksh编写的

点击查看英文原文

I had a similar issue, but not connected with a Python process. I was running a script which did a nohup and the script ran periodically via cron.

I was able to resolve the problem by:

  1. redirecting the stdin , stdout and stderr
  2. ensuring the the script being invoked via nohup didn’t run anything else in the background

PS: my scripts were written in ksh running on RHEL

声明：本站所有文章，如无特殊说明或标注，均为本站原创发布。任何个人或组织，在未征得本站同意时，禁止复制、盗用、采集、发布本站内容到任何网站、书籍等各类媒体平台。如若本站内容侵犯了原著者的合法权益，可联系我们进行处理。