使用cron启动python脚本并输出打印到文件 [英] Start python script with cron and output print to a file

问题描述

我使用cron启动一个python脚本，如下所示：

  #Python脚本每隔3分钟调用一次崩溃
 * / 3 * * * * /home/ubuntu/python_script.sh& 
  

我的脚本有几个打印调试。我想将这些消息打印到一个文件，例如/home/ubuntu/Logs.txt

我的脚本还检查python调用是否已经运行， t再次启动：

 ＃！/ bin / bash 
 lines = $（ps -ef | grep python_script。 py | wc -l）
 
 if [$ lines -ne 2];然后
 python python_script.py& 
 fi 
  

如何将我的邮件打印到此文件？我使用的是python 2.7

---

更新：用以下代码编辑我的代码：

1）将此添加为我的python脚本的第一行：

 从__future__ import print_function 
 

2）在上次导入后打开日志文件，然后添加测试打印：

  log = open（/ home / ubuntu / Logs.txt，w +）
 print ，file = log）
  



如果我简单地从终端运行它， 。但是如果我用cron安排它，它不会写入文件。

---

更新2：解决方案与logger命令。在我的shell脚本中，我不得不添加2>& 1（在shell脚本中，不是由ElmoVanKielmo描述的crontab）和| logger&。最终解决方案如下：

 ＃！/ bin / bash 
 lines = $（ps -ef | grep python_script .py | wc -l）
 
 if [$ lines -ne 2];然后
 python python_script.py 2>& 1 |记录器
 fi 
  

并将任何打印输出到/ var / log / syslog文件

b p $ p> * / 3 * * * * /home/ubuntu/my_script.sh>> /home/ubuntu/Logs.txt


它会将stdout重定向到此文件。

您可能还想要有stderr重定向（异常等），因此：

  * / 3 * * * * / home / ubuntu / my_script.sh>> /home/ubuntu/Logs.txt 2> /home/ubuntu/errors.txt 
  

或者您可以将它们全部放在一个文件中：

  * / 3 * * * * /home/ubuntu/my_script.sh> /home/ubuntu/Logs.txt 2>& 1 
  

I'm starting a python script using cron, like this:

#Python script called every 3 minutes in case script crashes
*/3 * * * * /home/ubuntu/python_script.sh &

And my script has several prints for debugging. I want to print those messages into a file, for example /home/ubuntu/Logs.txt

My script also check if the python call is already running so it won't start it again:

#!/bin/bash
lines=$(ps -ef | grep python_script.py | wc -l)

if [ $lines -ne 2 ]; then
    python python_script.py &
fi

How do I print my messages to this file? I'm using python 2.7

---

Update: Edited my code with the following:

1) Added this as the first line of my python script:

from __future__ import print_function

2) Opened the log file after the last import, and right after that added a test print:

log = open("/home/ubuntu/Logs.txt", "w+")
print("Testing...", file = log)

If I simple run it from the terminal, it prints to the file fine. But if I schedule it with cron it doesn't write to the file.

---

Update 2: Ended up stumbling on a solution with "logger" command. On my shell script I had to add "2>&1" (in the shell script, not crontab as described by ElmoVanKielmo) and " | logger &". Final solution looks like this:

#!/bin/bash
lines=$(ps -ef | grep python_script.py | wc -l)

if [ $lines -ne 2 ]; then
    python python_script.py 2>&1 | logger &
fi

and it outputs any prints to /var/log/syslog file, which is good enough for me.

解决方案

In your crontab put this:

*/3 * * * * /home/ubuntu/my_script.sh >> /home/ubuntu/Logs.txt

It will redirect stdout to this file.
You might also want to have stderr redirected (exceptions etc.), so:

*/3 * * * * /home/ubuntu/my_script.sh >> /home/ubuntu/Logs.txt 2>> /home/ubuntu/errors.txt

Or you can have them all in one file:

*/3 * * * * /home/ubuntu/my_script.sh >> /home/ubuntu/Logs.txt 2>&1

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