linux之getcwd函数解析

[lingyun@localhost getcwd]$ cat getcwd.c

/*********************************************************************************

 *      Copyright:  (C) 2013 fulinux<fulinux@sina.com> 

 *                  All rights reserved.

 *

 *       Filename:  getcwd.c

 *    Description:  This file 

 *                 

 *        Version:  1.0.0(08/06/2013~)

 *         Author:  fulinux <fulinux@sina.com>

 *      ChangeLog:  1, Release initial version on "08/06/2013 03:56:30 PM"

 *                 

 ********************************************************************************/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

int main(void)

{

    char *ptr;

    int size = 50;

    if(chdir("/usr/tmp/yum-lingyun-sYjnfB") < 0)

    {

        perror("chdir");

        exit(1);

    }

    ptr = malloc(size);

    if(getcwd(ptr, size) == NULL)

    {

        perror("getcwd");

        exit(1);

    }

    printf("cwd = %s\n", ptr);

    exit(0);

}

[lingyun@localhost getcwd]$ ll /usr/

total 224

dr-xr-xr-x.   2 root root 69632 Apr 29 03:32 bin

drwxr-xr-x.   2 root root  4096 Sep 23  2011 etc

drwxr-xr-x.   2 root root  4096 Sep 23  2011 games

drwxr-xr-x.  39 root root  4096 Apr 15 15:44 include

dr-xr-xr-x.  29 root root  4096 Apr 22 03:18 lib

dr-xr-xr-x. 132 root root 86016 Apr 29 03:32 lib64

drwxr-xr-x.  30 root root 12288 Apr 29 03:32 libexec

drwxr-xr-x.  15 root root  4096 Jun  5 19:57 local

drwxr-xr-x    3 root root  4096 Apr 21 20:38 man

dr-xr-xr-x.   2 root root 12288 Jul 30 03:42 sbin

drwxr-xr-x. 265 root root 12288 Jun  9 09:34 share

drwxr-xr-x.   4 root root  4096 Jul  6  2012 src

lrwxrwxrwx.   1 root root    10 Jul  6  2012 tmp -> ../var/tmp

[lingyun@localhost getcwd]$ ls /usr/tmp/yum-lingyun-sYjnfB/

[lingyun@localhost getcwd]$ gcc getcwd.c 

[lingyun@localhost getcwd]$ ./a.out 

cwd = /var/tmp/yum-lingyun-sYjnfB

[lingyun@localhost getcwd]$