阿里云提供的一个监测cpu和内存的shell脚本（get_cpu_mem_info.sh）

nohup bash get_cpu_mem_info.sh &

1,下载该文件解压后，上传到 /tmp 目录中。
2,运行 cd 切换到/tmp目录。
3,执行： nohup bash get_cpu_mem_info.sh &
该工具会在 /tmp 目录下生成一个日志文件，记录实时监控系统的 CPU、内存的使用情况，等到系统异常时可以用于分析日志。

#!/bin/bash
#When the free memory very less ,this script to collect CPU/memory usage information and dmessage information.
#Version 1.0 time:2014-3-11
#Version 2.0 time:2014-12-23

logfile=/tmp/$0.log

check_os_release()
{
while true
do
os_release=$(grep "Red Hat Enterprise Linux Server release" /etc/issue 2>/dev/null)
os_release_2=$(grep "Red Hat Enterprise Linux Server release" /etc/redhat-release 2>/dev/null)
if [ "$os_release" ] && [ "$os_release_2" ]
then
if echo "$os_release"|grep "release" >/dev/null 2>&1
then
os_release=redhat
echo "$os_release"
else
os_release=""
echo "$os_release"
fi
break
fi
os_release=$(grep "Aliyun Linux release" /etc/issue 2>/dev/null)
os_release_2=$(grep "Aliyun Linux release" /etc/aliyun-release 2>/dev/null)
if [ "$os_release" ] && [ "$os_release_2" ]
then
if echo "$os_release"|grep "release" >/dev/null 2>&1
then
os_release=aliyun
echo "$os_release"
else
os_release=""
echo "$os_release"
fi
break
fi
os_release_2=$(grep "CentOS" /etc/*release 2>/dev/null)
if [ "$os_release_2" ]
then
if echo "$os_release_2"|grep "release" >/dev/null 2>&1
then
os_release=centos
echo "$os_release"
else
os_release=""
echo "$os_release"
fi
break
fi
os_release=$(grep -i "ubuntu" /etc/issue 2>/dev/null)
os_release_2=$(grep -i "ubuntu" /etc/lsb-release 2>/dev/null)
if [ "$os_release" ] && [ "$os_release_2" ]
then
if echo "$os_release"|grep "Ubuntu" >/dev/null 2>&1
then
os_release=ubuntu
echo "$os_release"
else
os_release=""
echo "$os_release"
fi
break
fi
os_release=$(grep -i "debian" /etc/issue 2>/dev/null)
os_release_2=$(grep -i "debian" /proc/version 2>/dev/null)
if [ "$os_release" ] && [ "$os_release_2" ]
then
if echo "$os_release"|grep "Linux" >/dev/null 2>&1
then
os_release=debian
echo "$os_release"
else
os_release=""
echo "$os_release"
fi
break
fi
break
done
}

rhel_fun()
{
while true
do
vm_mem=$(free -m|grep "buffers/cache"|awk '{print $4}')
cpu=$(top -bn2|grep "Cpu(s)"|awk '{print $8}'|awk -F'%' '{print $1}'|tail -n1)
check_cpu=$(echo "$cpu <20" |bc)
if [[ $vm_mem -le 100 ]] || [[ $check_cpu -eq 1  ]]
then
echo "======================================================" >>$logfile
date >>$logfile
echo "======================================================" >>$logfile
echo "The memory is too less." >>$logfile
free -m >>$logfile
echo "=======================CPU info========================" >>$logfile
(ps aux|head -1;ps aux|sort -nrk3|grep -v "RSS") >>$logfile
echo "=======================Memory info=====================" >>$logfile
(ps aux|head -1;ps aux|sort -nrk6|grep -v "RSS") >>$logfile
date >>$logfile
echo "=======================Dmesg info=====================" >>$logfile
dmesg >>$logfile
dmesg -c
fi
sleep 10
done
}

debian_fun()
{
while true
do
vm_mem=$(free -m|grep "buffers/cache"|awk '{print $4}')
cpu=$(top -bn2|grep "Cpu(s)"|awk '{print $5}'|awk -F'%' '{print $1}'|tail -n1)
check_cpu=$(echo "$cpu <20" |bc)
if [[ $vm_mem -le 100 ]] || [[ $check_cpu -eq 1  ]]
then
echo "======================================================" >>$logfile
date >>$logfile
echo "======================================================" >>$logfile
echo "The memory is too less." >>$logfile
free -m >>$logfile
echo "=======================CPU info========================" >>$logfile
(ps aux|head -1;ps aux|sort -nrk3|grep -v "RSS") >>$logfile
echo "=======================Memory info=====================" >>$logfile
(ps aux|head -1;ps aux|sort -nrk6|grep -v "RSS") >>$logfile
date >>$logfile
echo "=======================Dmesg info=====================" >>$logfile
dmesg >>$logfile
dmesg -c
fi
sleep 10
done
}

check_os_release

case "$os_release" in
redhat|centos|aliyun)
yum install bc -y
rhel_fun
;;
debian|ubuntu)
apt-get install bc -y
debian_fun
;;
esac