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LFCA 9 🐧 The Linux Filesystem Hierarchy
Linux organizes every file into a single tree — one root, many branches, no drive letters. The Filesystem Hierarchy Standard (FHS) defines what lives where: /etc for configuration, /home for user data, /var for variable data, /usr for programs, /tmp for temporary files. Every Linux distribution follows this standard, so once you know the layout,…
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LFCE 9 🐧 CIDR Notation Explained
CIDR notation is the syntax that made classless routing operational. It compresses the essential information of an IP prefix—the network address and the length of the network portion—into a single compact string: 192.168.1.0/24. The slash is not decoration. It separates the address from the prefix length, and that prefix length is the number of leading…
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LFCS 9 🐧 Creating Files and Directories — touch, mkdir
A filesystem is a tree of directories and files. Creating them is the first operation in any task that involves new data. The LFCS exam includes tasks that require creating a directory structure, initializing a file, or setting up a path for a service. The two commands for this are touch, which creates an empty…
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Linux CLI 9 🐧 whatis,apropos and info commands
These three commands help you discover and explore commands on your system. They’re complementary tools for finding the right command and learning more about it. Overview Command Purpose Best For whatis One-line description of a command Quick lookup when you know the name apropos Search by keyword Finding a command when you don’t know its…
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Bash Scripting 10 🐧 For Loops — Iterating over sequences, lists, and file patterns
A for loop is the construct that repeats a command list once for each item in a sequence. In Bash, the sequence can be a literal list of words, a range of numbers, the output of a command, an array’s elements, or the files matched by a glob pattern. The loop variable takes on each…
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LFCA 10 🐧 Important Directories Explained
Chapter 9 covered the whole filesystem tree. This chapter goes deeper — into the specific directories you’ll use every day and the files inside them that matter most. Knowing that /etc holds configs is one thing; knowing that /etc/passwd, /etc/fstab, and /etc/hosts are the ones you’ll actually edit is another. This chapter picks the ten…
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LFCE 10 🐧 VLSM — Variable Length Subnet Masking
Variable Length Subnet Masking is the technique that turns a single address block into a hierarchy of differently sized subnets. Fixed-length subnetting forces every subnet to use the same mask, which means every subnet holds the same number of hosts. This works when all segments have identical requirements. It fails when a network contains a…
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LFCS 10 🐧 Copying Files and Directories — cp
The cp command copies files and directories. It creates a new file or directory at the destination with the same contents as the source, leaving the source unchanged. It is one of the most-used commands in the shell, and the LFCS exam includes tasks that require copying files to a specific location, preserving permissions, and…
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Linux CLI 10 🐧 create your aliases
Aliases let you create custom shortcuts for commands — long commands, frequent combinations, or anything you type often. They save time and reduce typos. Overview Command Description alias Show all existing aliases alias lmh=’cd ~/cli; ls’ Create a temporary alias nano ~/.bashrc Edit shell config file source ~/.bashrc Apply changes unalias lmh Remove an alias…