如何检查目录是否存在？

发布于 2024-08-18 07:11:55 字数 180 浏览 4 评论 0原文

我将如何检查 FILE 是否是目录？我已经

if (file == NULL) {  
    fprintf(stderr, "%s: No such file\n", argv[1]);  
    return 1;  
}

检查了节点是否存在，但我想知道它是目录还是文件。

原文

How would I go about checking if a FILE is a directory? I have

if (file == NULL) {  
    fprintf(stderr, "%s: No such file\n", argv[1]);  
    return 1;  
}

and that checks if the node exists at all, but I want to know if it's a dir or a file.

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韵柒 2024-08-25 07:11:55

文件名本身不包含任何关于它们是否存在或它们是否是目录的信息 - 有人可以在您的下面更改它。您想要做的是运行一个库调用，即 stat(2)，它会报告文件是否存在以及文件是什么。从手册页来看，

[ENOENT]           The named file does not exist.

有一个错误代码报告（在 errno 中）该文件不存在。如果它确实存在，您可能希望检查它是否实际上是一个目录而不是常规文件。您可以通过检查返回的结构中的 st_mode 来完成此操作：

The status information word st_mode has the following bits:
...
#define        S_IFDIR  0040000  /* directory */

检查联机帮助页以获取更多信息。

Filenames themselves don't carry any information about whether they exist or not or whether they are a directory with them - someone could change it out from under you. What you want to do is run a library call, namely stat(2), which reports back if the file exists or not and what it is. From the man page,

[ENOENT]           The named file does not exist.

So there's an error code which reports (in errno) that the file does not exist. If it does exist, you may wish to check that it is actually a directory and not a regular file. You do this by checking st_mode in the struct returned:

The status information word st_mode has the following bits:
...
#define        S_IFDIR  0040000  /* directory */

Check the manpage for further information.

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时光礼记 2024-08-25 07:11:55

struct stat st;
if(stat("/directory",&st) == 0) 
        printf(" /directory is present\n");

struct stat st;
if(stat("/directory",&st) == 0) 
        printf(" /directory is present\n");

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楠木可依 2024-08-25 07:11:55

使用 opendir 尝试将其作为目录打开。如果返回一个空指针，那么它显然不是一个目录:)

这是您的问题的片段：

  #include <stdio.h>
  #include <dirent.h>

   ...

  DIR  *dip;
  if ((dip = opendir(argv[1])) == NULL)
  {         
     printf("not a directory");
  }
  else closedir(dip);

use opendir to try and open it as a directory. If that returns a null pointer it's clearly not a directory :)

Here's a snippet for your question:

  #include <stdio.h>
  #include <dirent.h>

   ...

  DIR  *dip;
  if ((dip = opendir(argv[1])) == NULL)
  {         
     printf("not a directory");
  }
  else closedir(dip);

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