#!/bin/sh
# Script to display CPU usage

# Cache in tmpfs to improve speed and reduce SSD load
cache=/tmp/cpu-script-cache
rm /tmp/cpu-script-cache 2>/dev/null
while true; do
    sleep 1
    cpu_stats=$(awk '/^cpu / {print $2 + $3 + $4 + $5, $5}' /proc/stat)
    if [ ! -f "$cache" ]; then
        printf "   ---%%   \r"
        echo "$cpu_stats" >"$cache"
        continue
    fi
    prev_stats=$(cat "$cache")
    echo "$cpu_stats $prev_stats" | awk '{
    total_diff = $1 - $3
    idle_diff = $2 - $4
    if (total_diff == 0) {
        usage = 0
    } else {
        usage = 100 * (1 - idle_diff / total_diff)
    }
    printf "   %.1f%%   \r", usage
    exit
}'
    echo "$cpu_stats" >"$cache"
done