Fixing "Permission denied" in Cron
Permission denied usually means the script lacks the execute bit, or you called it directly without an interpreter. Make it executable or call it via its interpreter.
The crontab line
0 * * * * /bin/bash /opt/app/job.sh
Running the interpreter explicitly avoids needing the execute bit on the script.
Or make it executable
chmod +x /opt/app/job.sh, keep a correct shebang like #!/bin/bash, then call it directly.
Check file ownership
If the job runs as another user (root or www-data), that user must have read/execute on the script and its parent directories.
FAQ
Why does my cron job say permission denied?
The script is not executable or lacks a shebang. chmod +x it, or run it via its interpreter like /bin/bash script.sh.
Do cron scripts need chmod +x?
Only if you call them directly. If you invoke bash script.sh or python script.py, the execute bit is not required.
Cron works for me but not for root?
Check that root can read and execute the script and every parent directory; ownership or 700 perms on your home dir can block it.