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#!/bin/bash
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# 内存缓存清理脚本 v1.2
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# 安全模式：当可用内存 >20% 时不执行清理
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MIN_FREE_PERCENT=20  # 触发清理的阈值
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echo "[$(date +'%F %T')] 检查内存状态..."
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# 获取内存信息（total, used）
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read -r total used _ <<< $(free -m | awk '/Mem:/{print $2,$3}')
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# 计算当前"可用率"（使用 available 字段更准确）
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free_percent=$(( (total - used) * 100 / total ))
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if [ "$free_percent" -lt "$MIN_FREE_PERCENT" ]; then
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    echo "内存可用率 ${free_percent}% < ${MIN_FREE_PERCENT}%，执行清理..."
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    # 安全清理步骤
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    sync
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    echo 1 > /proc/sys/vm/drop_caches
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    sleep 1
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    echo 2 > /proc/sys/vm/drop_caches
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    sleep 1
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    echo 3 > /proc/sys/vm/drop_caches
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    # 使用 available 字段计算最新可用百分比（更准确）
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    new_free=$(free -m | awk '/Mem:/{printf "%.1f", $7/$2*100}')
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    echo "清理完成 → 当前可用: ${new_free}%"
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else
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    echo "内存充足 (${free_percent}%)，跳过清理"
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fi

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[Unit]
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Description=Memory Cache Cleaner
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After=syslog.target
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[Service]
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Type=oneshot
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ExecStart=/usr/local/bin/cache_cleaner.sh
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User=root
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ProtectSystem=full

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[Unit]
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Description=Run memory cleaner every 3 hours
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[Timer]
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OnCalendar=*-*-* 0/3:00:00
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RandomizedDelaySec=300
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Persistent=true
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[Install]
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WantedBy=timers.target