linux - 使用 shell 脚本比较 cpuusage 值

Question

我如何使用 shell 脚本比较 CPU 使用率值，我在 if [ $message -ne ""] 行收到一个错误 [: =: unary operator expected ]

   #!/bin/sh

    expected_cpuusage="95"
    cpu_usage=`top -n 1 -b|grep Cpu|awk '{print $2}'|cut -d"%" -f1""`
    message=""
    if [ $cpu_usage -gt $expected_cpuusage ]    ##{x%?}
    then
       echo "CPU usage exceeded";
       if [ $message -ne "" ]
       then
         message="$message\n\nCPU usage exceeded configured usage limit \nCurrent CPU usage is $cpu_usage\nConfigured CPU usage is $expected_cpuusage";
       else
         message="CPU usage exceeded configured usage limit \nCurrent CPU usage is $cpu_usage\nConfigured CPU usage is $expected_cpuusage";
       fi ;
    fi

Answer 1

Use more quotes :

if [ "$message" -ne "" ]

否则空字符串会弄乱表达式。

更好的是:

if [ -n "$message" ]