China DOS Union

The Command Line section hasn't had new posts in a long time, so I'll just post a casual thread.

Let's discuss the most destructive commands! Many people will immediately say: format, but that's not actually the case. Now everyone uses Windows; do you think the system will let you format just because you say format? With so many files in use, how can you format? You might say to format during startup, but think about it—does the system let you start just because you want to? Who doesn't know how to use msconfig these days? Which antivirus software wouldn't check for format? Therefore, those who choose format must be influenced by outdated dogma!

Then there's deltree. Many people fear this command, but happily, deltree no longer exists in systems like XP; its functionality has been completely replaced by rd!

Personally, I recommend rmdir because "rd /s /q C:" can quietly delete all deletable files under the C: drive without errors! If you add a for loop, the user's documents will be destroyed in an instant! P.S. I've had my system wiped by rd three times myself.

Now, copy—a mild-sounding command, right? Try "copy nul some.doc". Heh, the document is erased. Note that this is erasure, not deletion; it's irrecoverable! Unlike del or format, this type of erasure cannot be recovered by tools like undel, unformat, Recover4All, FinalData, or EasyRecovery! According to NSA standards, a file needs to be erased seven times to be secure, so using a for loop seven times will do. With for, you can also erase all files on drives D:, E:, and F: completely clean!

lformat is powerful but not very versatile!

Then there's erase. This command is quite obscure; many people don't know about it, so its danger is significant!

Are there any other strange and magical weapons of mass destruction commands to discuss? Feel free to share—batch files are also welcome. Remember that harddiskkiller.bat? It was so classic! I still remember it vividly.

[ Last edited by electronixtar on 2006-6-13 at 16:16 ]

Although the format command in CMD cannot directly format the system drive, it can format data drives, causing all data to be lost instantly.

I disagree. First, many disks contain "System Restore" folders that cannot be deleted. Second, some disks have pagefile.sys, which also cannot be deleted. Third, most software is installed on partitions after the C: drive, which again cannot be deleted. Most importantly, formatted disks can be recovered.

This post is somewhat vague. The first few are commands built into DOS/Windows. If I'm not mistaken, is the last one referring to the so-called "low-level format" program provided by Maxtor? What is the scope of our discussion here? If all such commands are included, there are far too many dangerous commands.

As for using the command `copy nul some.doc` to clear files, I am unsure of the environment you are referring to. I have not tested it in CMD, but it can still be recovered in DOS.

Originally posted by electronixtar at 2006-6-13 16:09:
Personally, I recommend rmdir, because "rd /s /q C:" can quietly delete all deletable files under the C: drive without error messages! If combined with a for loop, the user's documents will be destroyed instantly! P.S. I have had my system completely wiped by rd three times myself.

I have had the same experience. When testing malformed directories, I accidentally added an extra space, resulting in "rd /s /q " wiping everything....

Originally posted by electronixtar at 2006-6-13 04:09 PM:
As for the erase command, it is quite obscure and unfamiliar to many people, so it is very dangerous!

The erase command is not obscure at all; erase = del, which is fundamental to DOS.

Additionally, there is diskpart in Windows XP, which can modify partitions when used with appropriate scripts.

Hmm, why isn't anyone choosing lformat? I'll go with that.
I still think low-level formatting is the most powerful; even the partitions are gone, haha.
By the way, moderator, could you share that classic harddiskkiller.bat for us to reference?
Actually, reset.com is also quite powerful. If you use it repeatedly and excessively, the motherboard will definitely burn out, haha.

DEBUG!!

Debug calls interrupt 13H function 07!

What is function 07 of int 13H?

Wow, the 8th floor is impressive; I’m at a loss for words.

int13h should be related to hard disk operations

Originally posted by electronixtar at 2006-6-18 21:14:
Wow, the person on the 8th floor is impressive; I’m at a loss for words.

int13h should be related to hard disk operations

It should be formatting the hard disk.

To all:
The int13h interrupt is a BIOS interrupt, and function 07h is specifically for low-level formatting of hard disks. If the interleave factor is altered, the hard disk will essentially become useless. When used properly, it is far more powerful than DOS interrupts.

To 220110:
However, calls to it are blocked under Windows and Linux, making it not very practical. Additionally, it is ineffective when antivirus software is monitoring, as antivirus programs typically intercept interrupts that directly write to the hard disk.

[ Last edited by qe on 2006-6-21 at 00:41 ]

It seems that the `format` command in MS-DOS 6.22 has an undocumented switch that can write to the first cylinder (cluster/sector) of a "bad" hard drive, rendering the drive unreadable and unwritable in less than 5 seconds.

Directly editing the sector; this time, it should be completely deleted, I suppose.

Try the RECOVER command; the data was all overwritten in less than a few seconds.