Check if an absolute path of a directory or a file name are valid

问题

I'm creating a bat script and I should check whether a variable contains a valid absolute path of a directory and if another variable contains a valid name of a file for Windows 8 and above.

So, how would I go these checks?

Thanks

Bye

回答1:

This is much trickier than most people realize. There is lots of misinformation about this topic available on SO and elsewhere. There are many "solutions" that appear to work, but then fail under certain circumstances.

The problem can be divided into two parts:

1) Absolute or Relative

You cannot simply convert the path into a full path using FOR variable "%%~fF" or parameter "%~f1" and test to see if it matches the original string (ignoring case) because there are an infinite number of ways an absolute path can be written. A valid absolute path may have any number of \..\ or \.\ within it. Also, an absolute path may use a drive letter or it may be a UNC path. Also, an absolute path may include any number of " within it.

I test to see if a path is absolute or relative by first removing all quotes, and then I use FINDSTR to test if it begins with either of the following:

Drive letter, followed by colon, followed by backslash
Two back slashes

2) File or Folder or Not exists

It is easy to use IF EXISTS path to tell whether a path is valid or not. But it is more difficult to distinguish a file from a folder.

Back in the days of DOS, you could check if path\NUL exists, and if it does, then you knew that path was a folder. Unfortunately, many people are under the false impression that this works under Windows - It is not reliable under Windows

Another frequent attempt is to test if path\ exists, and if so, assume that it must be a folder. This often seems to work, but it does not work if the path involves directory symbolic links or junctions

The classification code I would use is nearly the same as for https://stackoverflow.com/a/8669636/1012053, except I have adopted it for use with an environment variable instead of a batch parameter.

I use the FOR variable ~a modifier to look at the file/folder attributes. If I find d then it is a folder. if I find attributes without d then it is a file. Else if I fail to find attributes then it does not exist.

The other method that appears to accurately tell whether a folder exists is to test if path\* exists, but I have less experience with this method.

So putting it all together, I get

@echo off
setlocal
set var=test.bat

setlocal enableDelayedExpansion

:: Determine absolute or relative
echo(!var:^"=!|findstr /i "^[A-Z]:[\\] ^[\\][\\]" >nul && set "type=absolute" || set "type=relative"

:: Determine file or folder or not exists
for /f eol^=^ delims^= %%F in ("!var!") do (
  for /f "tokens=1,2 delims=d" %%A in ("-%%~aF") do if "%%B" neq "" (
    echo %%F = %type% folder
  ) else if "%%A" neq "-" (
    echo %%F = %type% file
  ) else (
    echo %%F does not exist
  )
)

回答2:

Here is the self-explanatory code. It expects an argument containing the path to check.

set "INPUT_PATH=%~1"
set "FULL_PATH=%~f1"
set "SHORT_PATH=%~s1"
if /i "%INPUT_PATH%"=="%FULL_PATH%" echo this is a full path 
if exist "%INPUT_PATH%" echo this is an existing path
if exist %SHORT_PATH%\NUL echo this is a directory

来源：https://stackoverflow.com/questions/38169201/check-if-an-absolute-path-of-a-directory-or-a-file-name-are-valid

标签

validation

batch-file

filenames

absolute-path