Task for a junior DevOps candidate

Time: max 1 hour

Create a Bash script named log_cleanup.sh that does the following:

1. It searches for log files (*.log) older than 7 days in a specified directory /var/log/nginx/.
2. It moves these older log files to an archive directory /var/log/archive/.
3. Ensure the script logs its activities in a separate log file located at /var/log/log_cleanup_activity.log.
4. Make sure the script is executable and handles scenarios like empty directories or absence of log files.