What you will learn
- Move around the filesystem with confidence
- Read absolute vs relative paths
- Inspect files and directories
New to this? Start here
The basics, in plain English
Before any of this makes sense, here is the ground floor. A computer stores everything as files, and those files live inside folders. The shell is just a place where you type short text commands to move around those folders and open or change files, instead of clicking with a mouse.
- File
- A single saved thing on the computer: a photo, a note, a program. It has a name.
- Folder / directory
- A container that holds files and other folders. "Directory" is just the technical word for a folder.
- Filesystem
- The whole tree of folders inside folders, starting from one top folder, that holds everything on the machine.
- Terminal
- The black window where you type commands. Think of it as a chat box with the computer.
- Shell
- The program listening inside that window. You type a command, the shell runs it and shows the result.
- Command
- A short word you type to make something happen. "ls" lists files, "cd" changes folder.
- pwd
- Stands for "print working directory". It tells you which folder you are standing in right now.
- cd
- Stands for "change directory". It moves you into a different folder, like double-clicking a folder.
- ls
- Stands for "list". It shows you what files and folders are inside where you are.
Why the shell matters
Every server you touch in DevOps is driven from a shell. Mastering it is non-negotiable. The shell is a text interface to the kernel — you type commands, it runs programs.
Core navigation
Use pwd to print the working directory, cd to change it, and ls to list contents. Paths starting with / are absolute; everything else is relative to where you stand.
Inspecting files
cat dumps a whole file, less paginates it, head and tail read the ends, and file tells you what a thing actually is.
Try it yourself
$pwd↳Print the current directory so you always know where you are.$cd /var/log↳Move into the system log folder.$ls -lah↳List everything: long format, human-readable sizes, and hidden files.$tail -f syslog↳Stream a log live and keep printing new lines as they arrive.Finished this topic?
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