401 lines
8.6 KiB
Bash
Executable File
401 lines
8.6 KiB
Bash
Executable File
#!/bin/bash
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#
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# Shell 脚本调试流程示例
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# 展示常见的 Bash 脚本错误和调试方法
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#
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# ============================================
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# 调试设置
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# ============================================
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# 取消注释以启用调试模式
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# set -x # 打印每个命令
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# set -e # 错误时退出
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# set -u # 未定义变量报错
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# set -o pipefail # 管道中任何命令失败则失败
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# 或组合使用
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# set -xeuo pipefail # 严格模式
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# ============================================
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# 错误处理函数
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# ============================================
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# 错误退出函数
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die() {
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local message="$1"
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local exit_code="${2:-1}"
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echo "Error: $message" >&2
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exit "$exit_code"
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}
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# 记录函数
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log() {
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local level="$1"
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shift
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echo "[$(date '+%Y-%m-%d %H:%M:%S')] [$level] $*" >&2
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}
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log_info() { log "INFO" "$@"; }
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log_warn() { log "WARN" "$@"; }
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log_error() { log "ERROR" "$@"; }
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# ============================================
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# 问题 1：未引用的变量
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# ============================================
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# 错误示例：变量未引用
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demo_unquoted_variable() {
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echo "=== 问题 1：未引用的变量 ==="
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local name="John Doe"
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# 错误：变量未引用，空值会导致语法错误
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# if [ $name = "John Doe" ]; then
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# echo "Match"
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# fi
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# 正确：始终引用变量
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if [ "$name" = "John Doe" ]; then
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log_info "变量匹配: $name"
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fi
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}
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# ============================================
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# 问题 2：命令失败继续执行
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# ============================================
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demo_command_failure() {
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echo "=== 问题 2：命令失败继续执行 ==="
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# 错误：cd 失败后继续执行
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# cd /nonexistent_directory
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# rm -rf file.txt # 会删除当前目录的文件！
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# 正确：检查命令是否成功
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cd /tmp || die "无法切换到 /tmp 目录"
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log_info "成功切换到目录: $(pwd)"
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cd - > /dev/null || true
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}
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# ============================================
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# 问题 3：循环中的变量作用域（管道问题）
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# ============================================
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demo_pipeline_scope() {
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echo "=== 问题 3：管道中的变量作用域 ==="
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local count=0
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# 错误：管道创建子 shell，外部变量不改变
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# echo -e "1\n2\n3" | while read line; do
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# count=$((count + 1))
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# done
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# echo "Count: $count" # 输出 0
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# 正确：使用重定向
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while read line; do
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count=$((count + 1))
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done < <(echo -e "1\n2\n3")
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log_info "计数结果: $count"
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}
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# ============================================
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# 问题 4：数组操作
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# ============================================
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demo_array_operations() {
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echo "=== 问题 4：数组操作 ==="
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local fruits=("apple" "banana" "cherry")
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# 错误的数组访问
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# echo $fruits[1] # 输出 apple[1]
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# 正确的数组访问
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log_info "第一个元素: ${fruits[0]}"
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log_info "第二个元素: ${fruits[1]}"
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log_info "所有元素: ${fruits[@]}"
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log_info "数组长度: ${#fruits[@]}"
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# 遍历数组
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for fruit in "${fruits[@]}"; do
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log_info "水果: $fruit"
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done
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}
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# ============================================
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# 问题 5：字符串比较
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# ============================================
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demo_string_comparison() {
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echo "=== 问题 5：字符串比较 ==="
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local name="John"
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# 错误：数字比较使用 =
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# if [ $age = 18 ]; then
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# 正确：字符串比较
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if [[ "$name" == "John" ]]; then
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log_info "字符串匹配"
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fi
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# 正确：数字比较
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local age=18
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if [ "$age" -eq 18 ]; then
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log_info "数字匹配"
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fi
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}
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# ============================================
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# 问题 6：算术运算
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# ============================================
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demo_arithmetic() {
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echo "=== 问题 6：算术运算 ==="
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local a=10
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local b=5
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# 错误：使用 let 或 $(())
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# result = a + b # 这是命令调用
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# 正确的算术运算
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local result=$((a + b))
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log_info "加法: $a + $b = $result"
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result=$((a - b))
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log_info "减法: $a - $b = $result"
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result=$((a * b))
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log_info "乘法: $a * $b = $result"
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result=$((a / b))
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log_info "除法: $a / $b = $result"
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# 使用 let
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let result=a+b
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log_info "let 加法: $result"
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}
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# ============================================
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# 参数验证
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# ============================================
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validate_arguments() {
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echo "=== 参数验证 ==="
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# 检查参数数量
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if [ $# -lt 2 ]; then
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die "用法: $0 <文件> <目录>" 2
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fi
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local file="$1"
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local dir="$2"
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# 检查文件存在
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if [ ! -f "$file" ]; then
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die "文件不存在: $file" 3
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fi
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# 检查目录存在
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if [ ! -d "$dir" ]; then
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die "目录不存在: $dir" 4
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fi
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log_info "参数验证通过"
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log_info "文件: $file"
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log_info "目录: $dir"
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}
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# ============================================
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# 使用 trap 进行清理
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# ============================================
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demo_trap() {
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echo "=== 使用 trap 进行清理 ==="
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# 设置清理函数
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cleanup() {
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log_info "执行清理操作..."
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# 这里可以执行清理操作
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}
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# 捕获退出信号
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trap cleanup EXIT
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# 捕获错误信号
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trap 'log_error "发生错误，行号: $LINENO"' ERR
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# 捕获中断信号
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trap 'log_warn "脚本被中断"; cleanup; exit 130' INT
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log_info "执行一些操作..."
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# 模拟操作
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sleep 1
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}
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# ============================================
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# 调试技巧示例
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# ============================================
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demo_debugging() {
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echo "=== 调试技巧 ==="
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# 1. 使用 echo 调试
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local value="test"
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echo "[DEBUG] value = $value" >&2
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# 2. 使用 printf 格式化输出
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printf "[DEBUG] Count: %d, Name: %s\n" 42 "John" >&2
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# 3. 检查变量是否设置
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if [ -z "${unset_var+x}" ]; then
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log_warn "变量 unset_var 未设置"
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fi
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# 4. 显示调用栈
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log_info "调用栈:"
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local i=0
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while caller $i; do
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((i++))
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done 2>/dev/null || true
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}
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# ============================================
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# 文件操作错误处理
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# ============================================
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demo_file_operations() {
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echo "=== 文件操作错误处理 ==="
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local tmpfile=$(mktemp) || die "无法创建临时文件"
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# 确保文件被删除
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trap "rm -f '$tmpfile'" EXIT
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# 写入文件
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echo "Test content" > "$tmpfile" || die "无法写入文件: $tmpfile"
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# 读取文件
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local content
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content=$(cat "$tmpfile") || die "无法读取文件: $tmpfile"
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log_info "文件内容: $content"
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# trap 会自动清理
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}
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# ============================================
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# 带重试的操作
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# ============================================
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demo_retry() {
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echo "=== 带重试的操作 ==="
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local max_attempts=3
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local attempt=1
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while [ $attempt -le $max_attempts ]; do
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log_info "尝试 $attempt/$max_attempts..."
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# 模拟可能失败的操作
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if [ $attempt -eq 2 ]; then
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log_info "成功！"
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return 0
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fi
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log_warn "失败，重试..."
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((attempt++))
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sleep 1
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done
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log_error "所有尝试都失败了"
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return 1
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}
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# ============================================
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# 检查依赖
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# ============================================
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check_dependencies() {
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echo "=== 检查依赖 ==="
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local required_commands=("curl" "jq" "git")
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for cmd in "${required_commands[@]}"; do
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if ! command -v "$cmd" &> /dev/null; then
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log_error "缺少依赖: $cmd"
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return 1
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fi
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log_info "✓ $cmd 可用"
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done
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log_info "所有依赖都已满足"
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}
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# ============================================
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# 主函数
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# ============================================
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main() {
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echo "============================================"
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echo "Shell 脚本调试示例"
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echo "============================================"
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# 运行各个示例
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demo_unquoted_variable
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echo ""
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demo_command_failure
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echo ""
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demo_pipeline_scope
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echo ""
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demo_array_operations
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echo ""
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demo_string_comparison
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echo ""
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demo_arithmetic
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echo ""
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demo_trap
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echo ""
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demo_debugging
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echo ""
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demo_file_operations
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echo ""
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demo_retry
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echo ""
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check_dependencies
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echo ""
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log_info "所有示例执行完成"
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}
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# 运行主函数
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main "$@"
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