Linux OS
Linux File System - Directories explained
Here are the most important root directories and their purpose explained
/bin Contains binaries essential for the system to boot and perform basic functions. Programs like bash, login, etc reside in here. Do not modify anything in it.
/boot Contains the core assets needed to boot the system, ie, Bootloader, Linux Kernel Image, etc. Do not modify anything in it.
/proc Virtual filesystem maintained by the Kernel in order to run all processes. Don’t change anything in this dir. But you can look around. Every process has a corresponding directory inside it (named after process ID) where you get lots of information about it.
/var Contains files that are of variable size/content. Eg- All log files are stored inside /var/log by convention. Eg- Web Servers commonly store frontend assets in /var/www/html.
/mnt By convention, all devices manually mounted on to the system are mounted inside this directory.
/media Used for automatic mounting of devices such as USB drive.
/dev Contains files for all devices mounted on to your system. Eg- When you mount a new EBS volume to your linux-based EC2 instance, you’d usually see the device as "/dev/sda1". Eg- You may have seen Bash commands that send output to "/dev/null" to simply drop it.
/etc Contains System-wide configurations & Scripts that run during boot/initialization. All files are text-only so they’re human readable.
/tmp All temporary files are stored in this directory. It generally gets cleaned out when you reboot your system. Do not store any important data in /tmp. You will likely lose it.
/lib Contains all the libraries required by programs in /bin. A variation, /usr/lib, may contain libraries for user-space programs
/root Home directory of the root user in Linux. As a normal user, you may not have access to this directory at all.
/usr Contains all programs directly used by Linux users. Try exploring /usr/bin. What do you see?
/home Contains a home folder for each regular user on the system. If you are “ben”, then there will be a “/home/ben” directory on the system that you control. But you may or may not be able to access other users' home directories depending on your permissions.
TLS Certificates
Formerly known as SSL certificates, TLS certificates are used to secure communication between a client and a server. They are used to encrypt the data being sent between the two parties, preventing third parties from reading the data.
Free certificates at Let's Encrypt.