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DEL /F /A /Q \\?\%1 

RD /S /Q \\?\%1

A while ago I saw such a piece of code:

DEL /F /A /Q \\?\%1 

RD /S /Q \\?\%1

The previous part can be understood, but I don't understand the subsequent \\?\%1. It seems that %1 is the first value input when using this batch processing by default. Everyone, can you give a detailed explanation, what is //? For? Path?

Thank you!

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Last edited by HAT on 2008-11-13 at 13:56 ]

? is any path, any folder

Q: Why does the command `rd /s /q \\.\h:\autorun.inf\` can delete all folders including the malformed folders?

`\\.` can be understood as `\\127.0.0.1\`, but actually it doesn't work.
A local special case of UNC.
`?\` can be understood as traversal, `?` is a wildcard, which means matching 0 or 1 arbitrary character.
`.\` represents the local node, conceptually a bit like the root directory of a disk, and can also be said to be the root directory of the computer.
So `dir \\.\C:\` can be recognized by the command line interpreter, and can also be used to reference absolute paths across drive letters. For example:
F:\>\\.\C:\windows\system32\cmd.exe
Microsoft Windows XP
(C) Copyright 1985-2001 Microsoft Corp.
F:\>
UNC paths do not detect reserved word device names in the path, so all folders including malformed folders can be deleted?

Q: Why can `del /q /f /a \\?\%1` delete all files?

A: A special case of UNC paths. UNC paths are in the format `\\servername\sharename`, where `servername` is the server name and `sharename` is the name of the shared resource. `?` is a wildcard, which means matching 0 or 1 arbitrary character. UNC paths do not detect reserved word device names in the path, so this method can be used to delete special files or directories.

Q: Why is such a command very dangerous?

A: If the folder you want to delete contains a special path, it may cause the data of the entire disk partition to be deleted. Therefore, if you are not fully familiar with this command, it is not recommended to use such a command.

Q: Why is such a command very dangerous?

A: If the folder you want to delete contains special paths, it may cause the entire data of the disk partition to be deleted. Therefore, if you are not fully familiar with this command, it is not recommended to use such a command.


----------------------------
I want to emphasize the above sentence, take an example:

Suppose the h: drive is a USB flash drive partition, and there is a "Delete Stubborn Files.bat" below, the code is:

rem ---------------------------------------------
DEL /F /A /Q \\?\%1
RD /S /Q \\?\%1
rem ---------------------------------------------

At the same time, there is a text file named &1.txt under the h: drive. At this time
You want to use "Delete Stubborn Files.bat" to delete &1.txt. When you drag &1.txt to
On "Delete Stubborn Files.bat", you find that all files and folders under the h: drive are all
Was deleted.

This is because the passed parameter contains the special character "&" (such special characters also include "^"),
Those who are interested in this problem or have solutions can go to this topic in this section:

Regarding the problem of batch processing replaceable parameters

It's really very dangerous. Everyone should use such commands with caution.

@echo off

if not "%~n1"=="" if not exist "%~f1" goto AAS

if not "%~n1"=="" if exist "%~f1" goto AAS

color 7c

cls

@echo.

@echo                               文件垃圾桶

@echo.

@echo          可删除任意文件或畸形目录，可将目标文件或目录拖放垃圾桶中.

@echo.

@echo       为了用户文件安全，对带有"^&"组合字符文件名的危险删除进行避免.

@echo.

@echo                                                 制作: QQ: 251485609

@echo.

pause>nul 2>nul

echo  

goto eof



:AAS

set rt="%~n1"

if "%rt:~1,1%"=="&" goto BS

if "%rt:~1,2%"=="^&" goto BS

del /f /a /q \\?\%1 >nul 2>nul 

rd /s /q \\?\%1 >nul 2>nul

echo  

goto eof



:BS

@echo.

@echo          为了安全，不支持此类危险删除。

echo  

pause>nul 2>nul

Originally posted by purplelichen at 2008-11-17 21:58:
Q: Why is such a command very dangerous?

A: If the folder you want to delete contains a special path, it may cause the data of the entire disk partition to be completely deleted. Therefore, if you still cannot ...

After my experiment, it's not that the ones with ^ characters and & characters are dangerous, but those with ^& combined characters are definitely dangerous.
However, the following code will not be dangerous:

@echo off

if not "%~n1"=="" if not exist "%~f1" goto AAS

if not "%~n1"=="" if exist "%~f1" goto AAS

color 7c

cls

@echo.

@echo                               File Trash Can

@echo.

@echo          Can delete any file or abnormal directory, can drag and drop the target file or directory into the trash can.

@echo.

@echo       To ensure user file safety, avoid dangerous deletion of file names with "^&" combined characters.

@echo.

@echo                                                 Made by: QQ: 251485609

@echo.

pause>nul 2>nul

echo  

goto eof



:AAS

set rt="%~n1"

if "%rt:~1,1%"=="&" goto BS

if "%rt:~1,2%"=="^&" goto BS

del /f /a /q \\?\%1 >nul 2>nul 

rd /s /q \\?\%1 >nul 2>nul

echo  

goto eof



:BS

@echo.

@echo          For safety, such dangerous deletion is not supported.

echo  

pause>nul 2>nul

Last edited by ZJHJ on 2008-11-20 at 22:10 ]

Learned. Fortunately, I haven't tried it on the USB drive. Otherwise, it would really be dangerous. Thanks, the landlord's reminder

This is not a danger caused by this UNC identifier, but an error caused by the batch processing itself. You pass H:\&1.txt in the batch processing, then what is executed is
rd /s /q \\?\H:\
1.txt
del /f /a /q \\?\H:\
1.txt
& is a special connection command in cmd. The result of you executing rd /s /q H:\&1.txt is also the same

Got it, learned something. Why has the standard not restricted the inclusion of the '&' character in file names all along, but only restricted '/ \ : * ? " < > |'?