Shell 脚本检查进程是否已经在运行，如果是则退出

Question

我有一个带有 status() 和 start() 方法的 shell 脚本。代码如下：

#function to check the jmeter processes running
status(){
     PID=$(ps -ef | grep jmeter|grep -v grep)
     echo "The jmeter processes running are: \n$PID"
}

#function to run the .jmx file given by the user at run time
start(){
     echo "Please enter the file name .jmx extension"
     read file
     echo "Please enter the log file name .jtl extension"
     read log_file
     sh /home/ubuntu/apache-jmeter-3.0/bin/jmeter.sh -n -t $file -l $log_file &
}
while [ "$1" != "" ]; do
case "$1" in
        start)
            jmeter_start
            ;;
         status)
            jmeter_status
            ;;
          *)
            echo $"Usage: $0 {start|status}"
            exit 1
        esac
   shift
done

现在当我运行这个脚本时，我必须检查它是否已经在运行，如果它正在运行，我必须退出。让我知道该怎么做。

Answer 1

在函数的开头添加一个标志并将其设置为1，在函数结束之前将其设置为0，随意查询。

#function to check the jmeter processes running
status(){
     PID=$(ps -ef | grep jmeter|grep -v grep)
     echo "The jmeter processes running are: \n$PID"
}

#function to run the .jmx file given by the user at run time
start(){
     export start_flag=1
     echo "Please enter the file name .jmx extension"
     read file
     echo "Please enter the log file name .jtl extension"
     read log_file
     sh /home/ubuntu/apache-jmeter-3.0/bin/jmeter.sh -n -t $file -l $log_file &
     export start_flag=0
}

另一种选择是写入外部文件并查询它。

Answer 2

实际上你已经拥有了大部分。您应该能够使用来自status 的代码来获取 PID 并检查它是否存在。如果是，则输出一些错误并退出。否则，做你已经拥有的。

start(){
   PID=$(ps -ef | grep jmeter|grep -v grep)

   if [ -z $PID ]; then
       echo "Error: JMeter already running"
       exit
   fi

   echo "Please enter the file name .jmx extension"
   read file
   echo "Please enter the log file name .jtl extension"
   read log_file
   sh /home/ubuntu/apache-jmeter-3.0/bin/jmeter.sh -n -t $file -l $log_file &

}