Python子进程仅在cron中返回非零退出状态 [英] Python Subprocess returns non-zero exit status only in cron

问题描述

我有一个Python脚本，可以管理一系列 CasperJS 任务并处理结果。它可以从命令行正常运行，但是当我在cron中运行脚本时，出现错误：

I have a Python script that manages a series of CasperJS tasks and processes the result. It runs well from the command line, but when I run the script in cron, I get the error:

CalledProcessError: Command '['/path/to/casperjs', '/path/to/doSomething.js', 'args']' returned non-zero exit status 1

在Python中，我称为CasperJS：

In Python, I call CasperJS:

response = subprocess.check_output(['/path/to/casperjs', '/path/to/doSomething.js', 'args'], shell=True)

我也尝试过 shell = False 和 Popen ，但是我得到了相同的结果结果。我还尝试将整个命令设置为字符串（而不是列表），但这也无济于事。

I have tried shell=False and Popen as well, but I get the same result. I also tried making the entire command a string (instead of list), but that didn't help either.

运行'/ path / to / casperjs /path/to/doSomething.js args'在shell中运行时返回退出代码0。

Running '/path/to/casperjs /path/to/doSomething.js args' returns exit code 0 when run in the shell.

我还添加了 PATH = / usr / bin：/ bin：/ sbin：/ usr / local / bin 到我的crontab都无济于事。 （如此问题中所建议。）

I have also added PATH=/usr/bin:/bin:/sbin:/usr/local/bin to my crontab to no avail. (As suggested in this question.)

有什么想法为什么只在cron中出现此错误？谢谢!!

Any ideas why I'm only getting this error in cron? Thanks!!

编辑：根据以下答案，设置 shell = False 和 stderr = subprocess.STDOUT 使一切正常...

In accordance with the answer below, setting shell=False and stderr=subprocess.STDOUT made everything work...

推荐答案

除了stdout之外，您还应该尝试捕获stderr，以便您可以准确查明该程序失败的原因（假设它确实为您打印了一些错误）

You should try to capture stderr in addition to stdout so that you can find out exactly why the program is failing (assuming it does indeed print some errors for you)

cmd = ['/path/to/casperjs', '/path/to/doSomething.js', 'args']
response = subprocess.check_output(cmd, 
                shell=True,
                stderr=subprocess.STDOUT)

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