shell实现对机器内存和CPU使用情况的监控

这个脚本主要的目的是监控机器上CPU和内存的使用情况，如果超过一定的阈值，打印出占用CPU或者内存资源较多的进程信息，也可以替换成其它方式。

主要功能如下：

1）将内存和CPU资源的监控情况记录到日志文件中

2）控制日志文件大小，周期性检查（30天）日志文件大小，当日志文件超过一定程度之后自动进行清理日志文件。

声明： 下面获取内存和CPU使用情况的代码参考《Linux.Shell编程从入门到精通》最后一个章节的部分代码，如有侵犯，请告知，谢谢。

#! /bin/bash
# this scripts is used to check host status(including memory CPU and so on)
# 20171024 -- first version

LOG_FILE="/tmp/monitor_log"
check_interval=10
max_usage_ration_memory=80
max_usage_ration_cpu=90
top_process_number=5


function check_log_size() {
    if [ -f "$1" ]
        then
        file_size=$(stat "$1" | grep Size | awk '{print $2}')
        echo "current log file size : $file_size"
        if [[ "$file_size" -gt 1048576 ]]
            then
            echo "Clean old records as log file($1) is too big $(date)" 2>&1 | tee "$1"
        fi
    fi
}


function disply_top_memory_process_information() {
    process_number=$(ps aux | sort -nk 4r | wc -l)
    echo "current process number is $process_number"
    if [[ "$process_number" -gt "$top_process_number" ]]
        then
        process_number=$((top_process_number+1))
    fi
    echo "the most $((process_number-1)) process costing memory resouces are as follows: " 2>&1 | tee -a "$1"
    echo "$(ps aux | sort -nk 4r | head -$process_number) " 2>&1 | tee -a "$1"
    echo "timestamp is $(date)"
}

function monitor_memory() {
    memory_total=$(grep MemTotal /proc/meminfo | awk '{print $2}' )
    memory_free=$(grep MemFree /proc/meminfo | awk '{print $2}' )
    memory_usage=$((100-memory_free*100/memory_total))
    echo "Current memory usage: $memory_usage at $(date)" 2>&1 | tee -a "$1"
    if [[ "$memory_usage" -gt "$max_usage_ration_memory" ]]
        then
        echo "Current Memory usage is too high  "
        disply_top_memory_process_information  "$1"
        return 1
    else
        return 0
    fi
}


function disply_top_cpu_process_information() {
    process_number=$(ps aux | sort -nk 3r | wc -l)
    echo "current process number is $process_number"
    if [[ "$process_number" -gt "$top_process_number" ]]
        then
        process_number=$((top_process_number+1))
    fi
    echo "the most $((process_number-1)) process costing cpu resouces are as follows: " 2>&1 | tee -a "$1"
    echo "$(ps aux | sort -nk 4r | head -$process_number) " 2>&1 | tee -a "$1"
    echo "timestamp is $(date)"
}


function get_cpu_info() {
    grep -i "^cpu[0-9]\+" /proc/stat | awk '{used+=$2+$3+$4; unused+=$5+$6+$7+$8} END {print used, unused}'
}


function monitor_cpu() {
    cpu_info_1=$(get_cpu_info)
    sleep "$check_interval"
    cpu_info_2=$(get_cpu_info)
    cpu_usage=$(echo "$cpu_info_1" "$cpu_info_2" | awk '{used=$3-$1;total+=$3+$4-$1-$2; print int(used*100/total)}')
    echo "Current cpu usage: $cpu_usage at $(date)" 2>&1 | tee -a "$1"


    if [[ "$cpu_usage" -gt "$max_usage_ration_cpu" ]]
        then
        echo "Current CPU usage is too high"
        disply_top_cpu_process_information $1
        return 1
    else
        return 0
    fi
}


check_time=1
check_log_size $LOG_FILE


while [[ "1" -lt "2" ]]
do
    check_time=$((check_time+1))
    if [[ "$check_time" -gt "367200" ]] #3600*24*30/10=367200
        then
        check_log_size $LOG_FILE
        check_time=1
    fi
    monitor_memory $LOG_FILE
    monitor_cpu $LOG_FILE
    sleep "$check_interval"
done