Shell脚本之while循环应用具体案例

#!/bin/bash

cpu_threshold=80
mem_threshold=75

echo "Monitoring CPU and Memory usage..."

while true; do
    cpu_usage=$(top -bn1 | grep "Cpu(s)" | awk '{print $2 + $4}') # 获取CPU使用率
    mem_usage=$(free | grep Mem | awk '{print $3/$2 * 100.0}') # 获取内存使用率
    
    if (( $(echo "$cpu_usage > $cpu_threshold" | bc -l) )); then
        echo "Warning: CPU usage is above threshold at $cpu_usage%"
    fi

    if (( $(echo "$mem_usage > $mem_threshold" | bc -l) )); then
        echo "Warning: Memory usage is above threshold at $mem_usage%"
    fi
    
    sleep 5 # 每隔5秒检查一次
done

#!/bin/bash

input_file="urls.txt"

while IFS= read -r url
do
    if curl --output /dev/null --silent --head --fail "$url"; then
        echo "$url is up"
    else
        echo "$url is down"
    fi
done < "$input_file"

#!/bin/bash

while true; do
    echo "Menu:"
    echo "1) Display current date and time"
    echo "2) List files in current directory"
    echo "3) Exit"
    read -p "Please enter your choice [1-3]:" choice

    case $choice in
        1)
            date
            ;;
        2)
            ls
            ;;
        3)
            echo "Exiting..."
            break
            ;;
        *)
            echo "Invalid option, please try again."
            ;;
    esac
done

#!/bin/bash

prefix="new_"

ls | while read -r file; do
    if [[ $file != ${prefix}* ]]; then
        mv "$file" "${prefix}${file}"
        echo "Renamed '$file' to '${prefix}${file}'"
    fi
done