linux下检测某个进程是否存在

#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<limits.h>
#include<iostream>



using  namespace std;



int main(int argc, char *argv[])
{
    FILE* fp=NULL;
    int count=0;
    int BUFSZ=100;
    char buf[BUFSZ];
    char command[150];


    //system() 也可以检测进程是否存在，但非常耗费资源
    sprintf(command, "ps -C %s|wc -l", "test" );


    if((fp = popen(command,"r")) == NULL)
    {
        cout<<"(fp = popen(command,\"r\")) == NULL"<<endl;
    }

    if( (fgets(buf,BUFSZ,fp))!= NULL )
    {
        count = atoi(buf);

        if((count - 1) == 0)
        {

            printf("%s not found\n","test");

            //可以用system()开启test
        }

        else
        {
           printf("process : %s total is %d\n","test",(count - 1));
        }

    }


    pclose(fp);
    fp=NULL;


   return 0;
}