linux C进程的执行函数exec系列

• 实验环境linux mint下面 QT5.11
• execlp失败时返回

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
int main()
{
    pid_t pid;
    pid_t pid2;
    pid=fork();
    char buf[1024];
    if(pid==0)
    {
        pid2=getpid();
        printf("this is a child process %d
",pid2);
        sprintf(buf,"/proc/%d/maps",pid2);//显示进程映射了的内存区域和访问权限
        execlp("/bin/cat","cat",buf,NULL);
    }
    else
    {
        printf("I am the parent %d and create the child %d
",getpid(),pid);
        sleep(40);
        wait(NULL);
        printf("child complete!");
    }
    return 0;
}

输出结果：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<fcntl.h>
int main()
{
    int fd;
    fd=open("monolog.txt",O_WRONLY|O_CREAT|O_TRUNC,0644);
    if(fd<0)
    {
        perror("open monolog.txt ");
        exit(1);
    }
    dup2(fd,STDOUT_FILENO);//把屏幕输出重定向到文件描述符
    execlp("ps","ps","ax",NULL);
    return 0;
}
操作结果：文件目录下生成文件，写入monolog.txt

• execv

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
int main()
{
    pid_t pid;
    pid=fork();
    if(pid==-1)
    {
        perror("fork error");
        exit(-1);
    }
    else if(pid>0)
    {
        sleep(10);
        printf("parent
");
    }
    else
    {
        char *argv[]={"ls","-1","-a","-h",NULL};
        execv("/bin/ls",argv);
    }
    return 0;
}