exec函数族

替换进程：exec系列

execl execlp execle execv execvp(库函数)execve(系统调用)

fork+exec创建一个新进程

//main1.c
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<assert.h>
#include<string.h>
#include<fcntl.h>
#include<sys/types.h>



int main(int argc,char *argv[],char *envp[])
{
    printf("main1 pid=%d\n",getpid());

    printf("argc=%d\n",argc);

    int i=0;
    for(;i<argc;i++)
    {
	printf("argv[%d]=%s\n",i,argv[i]);
    
    }
    for(i=0;envp[i]!=NULL;i++)
    {
	printf("envp[%d]=%s\n",i,envp[i]);
    }


    exit(0);
}

//main.c
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<assert.h>
#include<string.h>
#include<fcntl.h>
#include<sys/types.h>

int main(int argc,char*argv[],char*envp[])
{
    printf("main:pid=%d\n",getpid());

    //execl("/bin/ps","ps","-f",(char*)0);//用ps替换当前main程序  “ps”当前程序的名字，“-f”参数  execl执行成功装载ps程序执行
//当前新近程的路径加名称，
     //int execl(const char*path,const char*arg,...);//加路径

    //execlp("ps","ps","-f",(char*)0);
    //int execlp(const char*file,const char*arg,...);//不用加路径
    

    //execle("/bin/ps","ps","-f",(char*)0,envp);//(char*)0表示参数传递结束
    //int execle(const char*path,const char*arg,...,char *const envp[]);//多环境变量
  char* myenvp[10]={"EVD=hello","MYPATH=2f4wv"};
  execle("./main1","main1","hello","123",(char*)0,myenvp);//用main1替换当前程序 

    //char*myargv[10]={"ps","-f"};//参数列表，后面自动初始化为0
    //execv("/bin/ps",myargv);
    //int execv(const char*path,char* const argv[]);
    

    //char*myargv[10]={"ps","-f"};
    //char*myargv[10]={"abc","-f"};
    //execvp("ps",myargv);
    //int execvp(const char*file,char*const argv[]);
    

    //char*myargv[10]={"ps","-f"};
    //execve("/bin/ps",myargv,envp);//系统调用


   // execl("./main1","main1","hello","123",(char*)0);
    perror("execl error");//会打印为什么出错

    exit(0);
}