In the 1980s, GNU was developed at MIT. GNU stands for “GNU’s not Unix” and was made as a free, open source set of the existing Unix system tools. And in 1991, Linus Torvalds developed a free, open source version of the Unix kernel called Linux.
Linux is widely used today in mobile devices, desktops, supercomputers, data centers, and cloud servers.
Linux distributions (also known as distros) differ by their UIs, shell applications, and how the OS is supported and built.
The design of a distro is catered toward its specific audience and/or use case. Popular Linux distributions include Red Hat Enterprise Linux (RHEL), Debian, Ubuntu, SUSE (SLES, SLED, OpenSuse), Fedora, Mint, and Arch.
The Linux system consists of five key layers: the UI, application, OS, kernel, and hardware. The user interface enables users to interact with applications. Applications enable users to perform tasks within the system. The operating system runs on top of the kernel and is vital for system health and stability, and the kernel is the lowest-level software that enables applications to interact with hardware. Hardware includes all the physical or electronic components of your PC.
The Linux filesystem is a tree-like structure consisting of all directories and files on the system.
A Linux shell is an OS-level application that you can use to enter commands. You use a terminal to send commands to the shell, and you can use the cd command to navigate around your Linux filesystem.
You can use a variety of command-line or GUI-based text editors such as GNU nano, vim, vi, and gedit.
.deb and .rpm are distinct file types used by package mangers in Linux operating systems.
You can use GUI-based and command-line package managers to update and install software on Linux systems.
A shell is an interactive user interface. You use shell commands to navigate and work with files and directories.
The curl and wget commands display and download files from URLs, and thecat and tailcommands display file contents.
You can get user information with the whoami and idcommands, and get operating system information using the uname command. You can check system disk usage using the df command and monitor processes and resource usage with ps and top.Print string or variable value using echo,print and extract information about the date with the date command, and read the manual for any command using man.
ls lists all files and directories within a specified directory tree and cd navigates between directories. The find command finds files in your directories.
Relative paths are relative to your current working directory, while absolute paths stand independently
You can create files and directories with the touch and mkdir commands, delete them with rm and rmdir, and copy and move them cp and mv.
The cat, more, head, and tail commands allow you to sort and view file contents or view only a certain number of lines. Determine line, word, and character counts with wc.
You can use sort to view the lines of a file alphanumerically and uniq to remove repeated lines from your view. grep gets the lines of a file that match your desired criteria, and cut extracts slices and fields from lines. You can merge lines from different files using paste.
hostname and ifconfig allow you to view the network configuration. You can test a network connection using ping and send and receive data using curl and wget.
Compression preserves storage space, speeds data transfer, and reduces system load.
zip compresses files and folders prior to archiving them. tar archives and compresses files and directories into a tarball. unzip unpacks and decompresses a zipped archive, and tar can also decompress and unpack a tar.gz archive.