Linux commands

In this subsection, let's open the command line and execute some basic commands. In every Linux host, there are command-line interfaces named shells that interpret and execute typed commands and scripts. There are many shell environments, such as Bourne Again Shell (Bash, which is the most common shell), C shell (csh), Korn shell (ksh), and so on. To find the shells available for your environment, just open the command-line interface and type cat /etc/shells:

Now, let's get around some vital basic Linux commands from the shell:

pwd: To know which directory you are in
ls: To list files in a directory
cd: To enter a directory
mkdir: To create a new directory
rmdir: To remove a directory
touch: To create a new file
cat: To read a file
cp: To copy a file
mv: To move a file
man: To be shown how to use a command

Linux is case-sensitive (to give users many command option possibilities -T, - t, -a, - A, and so on), so you need to check how you are writing every command.

As a penetration tester, there are multiple important commands that you need to know in order to test the security posture of a Linux infrastructure:

hostname: Information about the host
cat /proc/version: Kernel information
uname -r: Kernel release
uname -a: More detailed information about the system
cat /proc/cpuinfo: Reads information about the processor
echo $PATH: Display information about the PATH variable
history: Display command history