Linux

Unix	Assembly language	Mathematics	Web development	I2P
GhostBSD	Assembly Programming Tutorial	Statistics	Django for Beginners	MuWire
GUI	Artificial intelligence	Artificial neural network	Machine learning	Messenger
Tkinter	Artificial intelligence	Artificial neural network	Machine Learning Mastery with Python	Session

Linux (/ˈlɪnəks/) is an operating system. It is regarded as one of Unix OSes. If you concern your security, you should use Linux. Because it is an open source software, there is no backdoor.

Ubuntu is an example of Linux.

Frequently used commands

You can use commands in the terminal.

ls

"ls" command shows the list of directories and files.

cd and ./

"cd" command changes a directory.

For example, in your home directory, if you type "cd tor-browser_en-US/", then the directory changes to "tor-browser_en-US/". It is same to "cd ./tor-browser_en-US/".

"." means your current directory.

".." stands for your upper directory.

If you input "cd ..", then your directory changes into the upper directory.

If you are in "tor-browser_en-US/" directory, you can excute Tor Browser. Just type "./s" and press "Tab" key, then "./start-tor-browser.desktop". will be automatically completed.

Not confuse "cd ./example" with "./example". "cd ./example" is changing a directory and "./example" is excuting a file.

passwd

Type following passwd command to change your own password:

$ passwd

You need to login as the root user, type the following command to change password for user vivek:

# passwd vivek

OR

$ sudo passwd vivek

rm

To delete a single file, use the "rm" command followed by the file name:

rm filename

To remove an empty directory, use either rmdir or rm -d followed by the directory name:

rm -d dirname
rmdir dirname

To remove non-empty directories and all the files within them, use the rm command with the-r (recursive) option:

rm -r dirname

If a directory or a file within the directory is write-protected, you will be prompted to confirm the deletion.

To remove non-empty directories and all the files without being prompted, use rm with the -r (recursive) and -f options:

rm -rf dirname

mv

For example, to move the file file1 from the current working directory to the /tmp directory you would run:

mv file1 /tmp

To rename a file you need to specify the destination file name:

mv file1 file2

The syntax for moving directories is the same as when moving files. In the following example, if the dir2 directory exists, the command will move dir1 inside dir2. If dir2 doesn’t exist, dir1 will be renamed to dir2:

mv dir1 dir2

memory usage

See memory usage.

free

See options. --help display this help and exit

free --help

-h, --human show human-readable output

free -h
free --human

--si use powers of 1000 not 1024

free --si

disk usage

See disk usage.

df

See options. --help display this help and exit

df --help

-h, --human-readable print sizes in powers of 1024 (e.g., 1023M)

df -h
df --human-readable

-H, --si print sizes in powers of 1000 (e.g., 1.1G)

df -H
df --si

List of Linux distributions

Debian

Tails: Tails serves as a pre-configured out-of-box secure OS which can be easily loaded onto removable media. Its ease of use while still forcing a secure protocol makes this OS a great contender. It's based on Debian. All its outgoing connections are forced to go through Tor, and non-anonymous connections are blocked. https://tails.boum.org/

Whonix: As with Tails, Whonix forces all communication through the Tor network. However, Whonix uses VirtualBox to usd a VM to ensure isolation of the user from the network. As such, it is a little more complex to setup and maintain. Nonetheless, Whonix serves as a viable alternative to the Tails OS for any user who wishes to keep a persistent OS on disk. It's based on Debian. https://www.whonix.org/

Kali Linux: While not geared towards being out of the box secure, Kali is a powerful tool to exploit network vulnerabilities. This OS comes prepackaged with tools to collect and analyze data in your network as well as having software for anti-forensics. If you have ever wanted to know how secure your system/network is - bombard it with Kali. Kali Linux is the new generation of the industry-leading BackTrack Linux penetration testing and security auditing Linux distribution. Kali Linux is a complete re-build of BackTrack from the ground up, adhering completely to Debian development standards. https://www.kali.org/

Ubuntu: It is a Debian based Linux distribution. https://www.ubuntu.com/

Linux Mint: It's an Ubuntu based Linux distribution. https://www.linuxmint.com/

Red Hat

CentOS: It's a Red Hat Enterprise Linux based Linux distribution. https://www.centos.org/

NSA request

Linus Torvalds, the founder of Linux kernel joked during a LinuxCon keynote 18 September 2013, that the NSA, who is the founder of SELinux, wanted a backdoor in the original kernel. However later, Linus' father, Member of the European Parliament (MEP), revealed that the NSA actually did this.

When my oldest son [Linus Torvalds] was asked the same question: “Has he been approached by the NSA about backdoors?” he said “No”, but at the same time he nodded. Then he was sort of in the legal free. He had given the right answer, [but] everybody understood that the NSA had approached him. -- Nils Torvalds, LIBE Committee Inquiry on Electronic Mass Surveillance of EU Citizens - 11th Hearing, 11 November 2013

Hot to mount an external H.D.D.

See Ubuntu.

Change a passphrase of LUKS

For more detail, see Ubuntu.