// proc/exec1.c 8-8#include "apue.h"#include 
    
     const char* env_init[] = { "USER=unknown", "PATH=/home/sunyj/apue/proc/", NULL };int main(void){    pid_t pid;    if ((pid = fork()) < 0)    {        err_sys("fork error");    }    else if (pid == 0)    {   /* specify pathname, specify environment */        if (execle("/home/sunyj/apue/proc/echoall", "echoall", "myarg1",                    "MY ARG2", (char *)0, env_init) < 0)        {            err_sys("execle error");        }    }    if (waitpid(pid, NULL, 0) < 0)    {        err_sys("wait error");    }    if ((pid = fork()) < 0)    {        err_sys("fork error");    }    else if (pid == 0)    {   /* specify filename, inherit environment */        if (execlp("echoall", "echoall", "only 1 arg", (char *)0) < 0)        {            err_sys("execlp error");        }    }    return 0;}
    

 

 

// proc/echoall.c 8-9#include "apue.h"int main(int argc, char *argv[]){    int			i;    char		**ptr;    extern char	**environ;    for (i = 0; i < argc; i++)		/* echo all command-line args */    {        printf("argv[%d]: %s\n", i, argv[i]);    }    for (ptr = environ; *ptr != 0; ptr++)	/* and all env strings */    {        printf("%s\n", *ptr);    }    return 0;}

 

我测试的结果是，execle可以正确执行，execlp报找不到echoall的错误，除非，我将echoall的路径在shell中加入环境变量PATH中，我不清楚是为什么。