ctop.sh

#!/bin/bash

# --- INITIALIZATION ---
# Hide cursor for a clean look
tput civis
# Ensure cursor returns on exit
trap "tput cnorm; echo -e '\nExiting...'; exit" SIGINT

# --- DATA GATHERING ---
get_stats() {
    # 1. CPU (From /proc/loadavg)
    read -r load1 _ _ _ _ < /proc/loadavg
    cores=$(grep -c ^processor /proc/cpuinfo)
    # Fast integer math: Load * 100 / Cores
    cpu_util=$(( (10#${load1/./} * 100) / (cores * 100) ))

    # 2. DISK & NET (Initial Snapshots)
    # Finds all physical disks skipping loop/ram
    readarray -t disks < <(lsblk -dno NAME | grep -v 'loop\|ram')
    for i in "${!disks[@]}"; do
        d="${disks[$i]}"
        io_start[$i]=$(awk -v d="$d" '$3==d {print $13}' /proc/diskstats)
    done

    # Finds active network interface
    net_dev=$(ip route get 8.8.8.8 2>/dev/null | sed -n 's/.* dev \([^ ]*\).*/\1/p')
    net_dev=${net_dev:-eth0}
    read rx1 tx1 < <(awk -v d="$net_dev:" '$1==d {print $2, $10}' /proc/net/dev)

    sleep 1 # Synchronized 1-second sample window

    # 3. DISK & NET (Final Snapshots)
    for i in "${!disks[@]}"; do
        d="${disks[$i]}"
        io_end[$i]=$(awk -v d="$d" '$3==d {print $13}' /proc/diskstats)
        disk_util[$i]=$(( (io_end[$i] - io_start[$i]) / 10 ))
        [ "${disk_util[$i]}" -gt 100 ] && disk_util[$i]=100
    done
    read rx2 tx2 < <(awk -v d="$net_dev:" '$1==d {print $2, $10}' /proc/net/dev)

    # Calculations
    rx_kb=$(( (rx2 - rx1) / 1024 ))
    tx_kb=$(( (tx2 - tx1) / 1024 ))
}

# --- ATOMIC RENDERING ---
render() {
    # Move cursor to top-left
    tput cup 0 0
    
    # Build the entire screen in a variable first for zero-flicker
    local out=""
    out+="\e[1;33mSYSTEM MONITOR: $(hostname) | $(date +%H:%M:%S)\e[0m\n"
    out+="----------------------------------------------------\n"
    out+="\e[1;34m--- CPU & LOAD ---\e[0m\n"
    out+="$(printf "Cores: %-4s | 1m Load: %-5s | Usage: %s%%" "$cores" "$load1" "$cpu_util")\e[K\n"
    
    out+="\n\e[1;32m--- MEMORY & SWAP ---\e[0m\n"
    out+="$(free -h | grep -E 'Mem|Swap' | column -t)\e[K\n"
    
    out+="\n\e[1;36m--- DISK I/O (% BUSY) ---\e[0m\n"
    for i in "${!disks[@]}"; do
        out+="$(printf "Device: %-10s | Utilization: %s%%" "${disks[$i]}" "${disk_util[$i]}")\e[K\n"
    done
    
    out+="\n\e[1;36m--- NETWORK ACTIVITY ---\e[0m\n"
    out+="$(printf "Interface: %-10s | IN: %s KB/s | OUT: %s KB/s" "$net_dev" "$rx_kb" "$tx_kb")\e[K\n"
    
    out+="\n\e[1;35m--- TOP PROCESSES (CPU) ---\e[0m\n"
    out+="$(ps -eo pid,pcpu,pmem,comm --sort=-pcpu | head -n 6 | tail -n +2 | column -t)\e[K\n"
    
    # Print the entire buffer at once
    echo -e "$out"
}

# --- MAIN ---
clear # Initial clear
while true; do
    get_stats
    render
done