解决unix环境高级编程的第一个程序运行问题

[root@localhost ~]# vi ls.c 

#include "apue.h"

#include <dirent.h>

int

main(int argc, char *argv[])

{

        DIR                             *dp;

        struct dirent   *dirp;

        if (argc != 2)

                err_quit("usage: ls directory_name");

        if ((dp = opendir(argv[1])) == NULL)

                err_sys("can't open %s", argv[1]);

        while ((dirp = readdir(dp)) != NULL)

                printf("%s\n", dirp->d_name);

        closedir(dp);

        exit(0);

}

~

~

~

"ls.c" 20L, 458C written

[root@localhost ~]# gcc ls.c 

ls.c:1:18: error: apue.h: No such file or directory

ls.c: In function amaina:

ls.c:13: error: aNULLa undeclared (first use in this function)

ls.c:13: error: (Each undeclared identifier is reported only once

ls.c:13: error: for each function it appears in.)

ls.c:16: warning: incompatible implicit declaration of built-in function aprintfa

ls.c:19: warning: incompatible implicit declaration of built-in function aexita

[root@localhost ~]# 

#include "apue.h"
#include <errno.h>      /* for definition of errno */
#include <stdarg.h>     /* ISO C variable aruments */

static void err_doit(int, int, const char *, va_list);

/*
* Nonfatal error related to a system call.
* Print a message and return.
*/
void
err_ret(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(1, errno, fmt, ap);
    va_end(ap);
}

/*
* Fatal error related to a system call.
* Print a message and terminate.
*/
void
err_sys(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(1, errno, fmt, ap);
    va_end(ap);
    exit(1);
}

/*
* Fatal error unrelated to a system call.
* Error code passed as explict parameter.
* Print a message and terminate.
*/
void
err_exit(int error, const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(1, error, fmt, ap);
    va_end(ap);
    exit(1);
}

/*
* Fatal error related to a system call.
* Print a message, dump core, and terminate.
*/
void
err_dump(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(1, errno, fmt, ap);
    va_end(ap);
    abort();        /* dump core and terminate */
    exit(1);        /* shouldn't get here */
}

/*
* Nonfatal error unrelated to a system call.
* Print a message and return.
*/
void
err_msg(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(0, 0, fmt, ap);
    va_end(ap);
}

/*
* Fatal error unrelated to a system call.
* Print a message and terminate.
*/
void
err_quit(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    err_doit(0, 0, fmt, ap);
    va_end(ap);
    exit(1);
}

/*
* Print a message and return to caller.
* Caller specifies "errnoflag".
*/
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)
{
    char    buf[MAXLINE];
   vsnprintf(buf, MAXLINE, fmt, ap);
   if (errnoflag)
       snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",
         strerror(error));
   strcat(buf, " ");
   fflush(stdout);     /* in case stdout and stderr are the same */
   fputs(buf, stderr);
   fflush(NULL);       /* flushes all stdio output streams */
}