Shell Scripts for Batch Renaming .sh Files and Monitoring Port 80 Requests

This guide presents two practical Bash scripts for Linux system administrators.

Task 1 – Rename and modify .sh files: The script searches the current directory (including sub‑directories) for files ending with .sh , renames each to .shell , and removes the second line of the renamed file.

#!/bin/bash ALL_SH_FILE=$(find . -type f -name "*.sh") for file in ${ALL_SH_FILE[*]} do filename=$(echo $file | awk -F'.sh' '{print $1}') new_filename="${filename}.shell" mv "$file" "$new_filename" sed -i '2d' "$new_filename" done

Task 2 – Monitor port 80 request volume: The script repeatedly obtains the request counts of the top‑20 IP addresses accessing port 80, checks whether the smallest count among them exceeds 500, and if so writes a system activity report to alert.txt ; otherwise it waits 600 seconds before retrying.

#!/bin/bash state="true" while $state do SMALL_REQUESTS=$(netstat -ant | awk -F'[ :]+' '/:22/{count[$4]++} END {for(ip in count) print count[ip]}' | sort -n | head -20 | head -1) if [ "$SMALL_REQUESTS" -gt 500 ]; then sar -A > alert.txt state="false" else sleep 600 continue fi done