Cron调度Python脚本异常：部分脚本显示运行但未执行任务

Let’s figure out why your 5720Check.py script triggers but doesn’t complete its tasks in Cron, even though it runs perfectly manually and your shorter script works without issues. Here are the most common culprits and actionable fixes:

1. Cron’s Environment Isn’t the Same as Your Shell #

Cron runs in a stripped-down environment with minimal variables—this is the #1 reason for "works manually but not in Cron" problems.

• Verify Your Python Path: Your shell might be using a different Python interpreter (like one from a virtual environment) instead of /usr/bin/python. Run which python in your console to get the correct path, then update your Cron rule. For example:

  55 10 * * * /home/vadim/your_venv/bin/python /home/vadim/5720Stab/5720Check.py
  

• Fix Relative Paths: If your script uses relative paths (like ./config.txt or ../data), Cron’s working directory is your home folder (/home/vadim), not the script’s directory. Replace all relative paths in the script with absolute paths, or add a cd command to your Cron rule to switch directories first:

  55 10 * * * cd /home/vadim/5720Stab && /usr/bin/python 5720Check.py
  

2. Capture Output to Debug Hidden Errors #

Cron doesn’t show errors or output by default (it usually sends them via unconfigured email). Redirect the script’s output and errors to a log file to see exactly what’s failing:

55 10 * * * /usr/bin/python /home/vadim/5720Stab/5720Check.py >> /home/vadim/5720Stab/cron_debug.log 2>&1

After the Cron job runs, check cron_debug.log for tracebacks, missing module errors, or "file not found" messages—this will point you directly to the issue.

3. Check If the OOM Killer Is Terminating Your Script #

Your 2-hour script might be using too much memory, causing Linux’s Out-of-Memory (OOM) Killer to shut it down. To confirm:

• Search system logs for OOM events:

  dmesg | grep -i oom
  

• Look in /var/log/syslog or /var/log/messages for entries mentioning "killed process" and your script’s name.
  If this is the case, optimize the script’s memory usage or adjust system resource limits.

4. Ensure No Interactive Steps Are Blocking Execution #

Double-check if 5720Check.py has any interactive prompts (like asking for a password or input) that work manually but hang in Cron (since there’s no user input available). Modify the script to use non-interactive authentication (e.g., credential config files) if needed.

5. Verify Permissions for Script and Resources #

While you can run the script manually, Cron runs with stricter umask settings. Make sure:

• The script has read permissions: chmod +r /home/vadim/5720Stab/5720Check.py
• Any files/directories the script accesses have the correct permissions for your user.

内容的提问来源于stack exchange，提问作者Irv1n