Seeking Parameter Explanation: DEL /F /A /Q \\?\%1 and RD /S /Q \\?\%1 - China DOS Union Forum

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.

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 '/ \ : * ? " < > |'?

Floor1　whiteyoo	Posted 2008-11-13 11:03
新手上路　Posts 11　Credits 16
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! ─────────────────　Moderation Record　───────────────── Performed: HAT Operation: Added search keywords in the post title; added code tags to the code Explanation: The original title " Seeking explanation of parameters in a piece of code" is not conducive to forum search Punishment: Deducted 2 points of points Tip: It is recommended to read the following posts {1415}The Wisdom of Asking Questions {7326}Must-read for forum newcomers, basic code of conduct for everyone {22703}Please don't be an impatient person {32667} Those people who can't even write the title clearly, wake up {32825}This version is strictly rectifying bad posts ─────────────────　Moderation Record　───────────────── [ Last edited by HAT on 2008-11-13 at 13:56 ]

Floor2　5872169	Posted 2008-11-13 13:21
高级用户　Posts 474　Credits 959
? is any path, any folder

Floor3　HAT	Posted 2008-11-13 13:24
版主　Posts 5,017　Credits 9,023
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.

Floor4　purplelichen	Posted 2008-11-17 21:58
新手上路　Posts 8　Credits 8
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

Floor5　radem	Posted 2008-11-19 12:17
高级用户　Posts 383　Credits 691
It's really very dangerous. Everyone should use such commands with caution.

Floor6　ZJHJ	Posted 2008-11-20 22:05
高级用户　Posts 374　Credits 609
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 ]

Floor7　menghen	Posted 2009-01-27 00:00
新手上路　Posts 6　Credits 10

Floor8　samliu	Posted 2009-02-05 22:14
新手上路　Posts 15　Credits 15
Learned. Fortunately, I haven't tried it on the USB drive. Otherwise, it would really be dangerous. Thanks, the landlord's reminder

Floor9　everest79	Posted 2009-02-06 17:20
金牌会员　Posts 1,127　Credits 2,564
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

Floor10　zhengqian529	Posted 2009-02-06 19:24
初级用户　Posts 93　Credits 100　From 湖南
Got it, learned something. Why has the standard not restricted the inclusion of the '&' character in file names all along, but only restricted '/ \ : * ? " < > \|'?