daemon.c

#include <unistd.h>#include <signal.h>#include <sys/param.h>#include <sys/types.h>#include <sys/stat.h>#include <errno.h>#include <stdlib.h>#include <stdio.h>#include <stdlib.h>#include <time.h>#include <syslog.h>void init_daemon(void){    int pid;    int i;    if(pid=fork())        exit(0);//是父进程，结束父进程    else if(pid< 0)        exit(1);//fork失败，退出    //是第一子进程，后台继续执行    setsid();//第一子进程成为新的会话组长和进程组长    //并与控制终端分离    if(pid=fork())        exit(0);//是第一子进程，结束第一子进程    else if(pid< 0)        exit(1);//fork失败，退出    //是第二子进程，继续    //第二子进程不再是会话组长    for(i=0;i< NOFILE;++i)//关闭打开的文件描述符        close(i);    //chdir("/tmp");//改变工作目录到/tmp    umask(0);//重设文件创建掩模    return;}void sig_term(int signo){    if(signo==SIGTERM) /*catchedsignalsentbykill(1)command*/    {        syslog(LOG_INFO,"log4j-agent program terminated.");        closelog();        exit(0);    }}int main(int argn, char** argv){    extern int errno;    if (argn>1)     {        init_daemon();//初始化为Daemon        openlog("log4j-agent", LOG_PID, LOG_USER);        syslog(LOG_INFO, "log4j-agent started.");        signal(SIGTERM,sig_term);/*arrangetocatchthesignal*/        char *p[argn + 1];        int j=0;        for(j=0; j<argn+1; j++){            p[j] = 0;        }        int i=1;        for(i=1; i<argn; i++){            p[i-1] = argv[i];        }        for(j=0; j<argn+1; j++){            printf("%s \n", p[j]);        }        int ret = execvp(argv[1], p);        if (ret<0){            //syslog(LOG_ERR, "execl failed:%s");            fprintf(stderr,"execl failed:%s", strerror(errno));            return -1;        }    }else{        printf("usage: ./daemon commond [argv] \n");        printf("su as: ./daemon java -jar log4j-agent.jar -f conf/log4j.xml -p 4561 \n");    }}

build

gcc daemon.c -o daemon

Usage:

./daemon java -jar log4j-agent.jar -f conf/log4j.xml -p 4561

You can run any program you want int linux with this ‘daemon’.