#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
 
void program_unique_check(const char* program)
{
    FILE    *fd;
    pid_t   id = 0;
    char    command[50] = {0};
    char    pid_num[50] = {0};
    const char* program_name;
 
    program_name = strrchr (program, '/');
 
    //过滤得到程序的文件名
    if (program_name)
        ++program_name;
    else
        program_name = program;
 
    //组成执行的命令ps -Ao pid,comm|grep xxx
    sprintf(command, "ps -Ao pid,comm|grep %s", program_name);
 
    printf ("Command to excute: %s\n", command);
 
    //以管道方式执行命令
    if ( (fd = popen(command, "r")) == NULL ) {
        perror("popen");
        exit(EXIT_FAILURE);
    }
 
    //从管道读回执行结果，这里只为了取得PID，所以只读取前最多20个字符（PID不可能有那么长吧！）
    fgets(pid_num, 20, fd);
    printf ("Result ：\n%s\n", pid_num);
 
    //转换结果字符为整形数值
    id = atoi(pid_num);
    printf ("DETECTED PID: %d\n", id);
 
    //判断是否自己
    if (getpid() == id)
        printf ("This's my self: %d\n", id);
    else {
        printf ("Here's one already running: %d\nI'll kill him!\n", id);
        //SIGKILL信号，当然也可以是其他信号的
        if ( kill (id, SIGKILL) == -1 ) {
    		perror("kill");
    		exit(EXIT_FAILURE);
        }
    }
}
 
int main (int argc, char**argv)
{
    program_unique_check(argv[0]);
    sleep (10);
    return 0;
}