PWD的编译及调试

实现mypwd

1 学习pwd命令

2 研究pwd实现需要的系统调用(man -k; grep),写出伪代码

3 实现mypwd

4 测试mypwd

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Linux命令学习：pwd命令

该命令用来显示目前所在的工作目录。指令英文原义：print work directory

执行权限    ：All User

指令所在路径：/usr/bin/pwd 或 /bin/pwd

命令语法：

pwd [OPTION]...

命令参数：

参数	长参数	描叙
-L	--logical（无效）	当目录为连接路径时，显示连接路径
-P	--physical（无效）	显示实际物理路径，而非使用连接（link）路径

查看pwd命令的帮助信息

root@DB-Server init.d]# man pwd
PWD(1)                           User Commands                          PWD(1)

    NAME
           pwd - print name of current/working directory

   SYNOPSIS
          pwd [OPTION]...

   DESCRIPTION
          Print the full filename of the current working directory.

         -L, --logical
                 use PWD from environment, even if it contains symlinks

          -P, --physical
                 avoid all symlinks

          --help display this help and exit

        --version
                output version information and exit

          NOTE:  your  shell  may  have  its  own version of pwd, which usually supersedes the version described here.  Please refer to your shell鈥檚 documentation for details about the
          options it supports.

   AUTHOR
          Written by Jim Meyering.

   REPORTING BUGS
          Report bugs to <bug-coreutils@gnu.org>.

   COPYRIGHT
          Copyright  2006 Free Software Foundation, Inc.
          This is free software.  You may redistribute copies of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY,  to
          the extent permitted by law.

  SEE ALSO
          The full documentation for pwd is maintained as a Texinfo manual.  If the info and pwd programs are properly installed at your site, the command

                 info pwd

          should give you access to the complete manual.

   pwd 5.97                                                      PWD(1)
  (END) 

PWD代码如下：

include
include<sys/stat.h>
include
include
include
include<sys/types.h>
void printpath();
char inode_to_name(int);
int getinode(char );
int main()
{
printpath();
putchar('\n');
return ;
}
void printpath()
{
int inode,up_inode;
char str;
inode = getinode(".");
up_inode = getinode("..");
chdir("..");
str = inode_to_name(inode);
if(inode == up_inode) {
// printf("/%s",str);
return;
}
printpath();
printf("/%s",str);
}
int getinode(char str)
{
struct stat st;
if(stat(str,&st) == -1){
perror(str);
exit(-1);
}
return st.st_ino;
}
char inode_to_name(int inode)
{
char str;
DIR dirp;
struct dirent dirt;
if((dirp = opendir(".")) == NULL){
perror(".");
exit(-1);
}
while((dirt = readdir(dirp)) != NULL)
{
if(dirt->d_ino == inode){
str = (char )malloc(strlen(dirt->d_name)sizeof(char));
strcpy(str,dirt->d_name);
return str;
}
}
perror(".");
exit(-1);
}

截图如下：