Ubuntu 16.04下incron触发bash脚本失败问题求助

Hey there! Since your basic incron operations (creating test.txt, logging echoes to syslog) are working, we can rule out core incron setup issues. Let's walk through the most common reasons your bash script might be failing, step by step:

1. Use Absolute Paths Everywhere #

Incron runs in a stripped-down environment, so relative paths won't work like they do in your regular shell.

• In your incron task: Always specify the full path to your script, e.g., /home/your_username/scripts/process_uploads.sh instead of ./process_uploads.sh.
• Inside your script: Any files, commands, or directories you reference should also use absolute paths. For example, if your script writes to output.log, use /home/your_username/uploads/output.log instead of output.log.

2. Verify Script Permissions #

Make sure the user running incron (either your regular user or root) has permission to execute the script and access its contents:

• Add execute permissions to the script:

  chmod +x /path/to/your_script.sh
  

• Ensure the script's parent directory has read/execute permissions for the incron user (e.g., chmod 755 /home/your_username/scripts).

3. Fix Missing Environment Variables #

Incron doesn't load your user's shell environment (like ~/.bashrc or ~/.profile), so commands in your script might fail because they're not in incron's limited PATH.

• Quick fix: Use absolute paths for all commands in your script. For example, use /usr/bin/ffmpeg instead of just ffmpeg.
• Alternative: Explicitly set the PATH at the top of your script:

  #!/bin/bash
  PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
  # Rest of your script...
  

4. Check the Script's Shebang #

Make sure your script starts with a valid shebang line to tell incron which shell to use. For bash scripts, this should be the first line:

#!/bin/bash

Omitting this or using the wrong shell (e.g., #!/bin/sh if your script uses bash-specific features) can cause silent failures.

5. Log Script Output to Debug #

The best way to see exactly what's going wrong is to redirect your script's stdout and stderr to a log file. Modify your incron task like this:

/path/to/uploads IN_CREATE /path/to/your_script.sh >> /home/your_username/incron_script_errors.log 2>&1

After triggering the incron event, check the log file—it will show you any errors (like "command not found" or "permission denied") that are causing the script to fail.

6. Confirm Incron User Access #

If you're running incron as a non-root user, double-check that your user is allowed in /etc/incron.allow (this file should contain your username, one per line). If /etc/incron.allow doesn't exist, make sure your user isn't listed in /etc/incron.deny.

Example Working Setup #

Here's a quick example to tie it all together:

Incron Task Entry #

/home/your_username/uploads IN_CREATE /home/your_username/scripts/handle_upload.sh >> /home/your_username/upload_logs.log 2>&1

Bash Script (handle_upload.sh) #

#!/bin/bash
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# Log the new file (incron passes the filename as $1)
echo "[$(date)] New file uploaded: $1" >> /home/your_username/upload_logs.log

# Add your custom processing here (use absolute paths!)
cp /home/your_username/uploads/$1 /home/your_username/processed_files/

Start with these checks—chances are one of these is the culprit. The log file will be your best friend for debugging any remaining issues!

内容的提问来源于stack exchange，提问作者matv1