Day27-Command-Line-Skills.md

Day 27 of Cisco Linux Essentials Course

Today I started Chapter 5 — Command Line Skills.

Why the Command Line Matters

Linux celebrates the CLI for its power, speed, and ability to accomplish tasks with a single instruction. Once you understand command structure, you become highly productive — and this skill transfers across ANY Linux distribution.

The Shell

The shell is the command line interpreter that translates typed commands into actions performed by the OS. The most common shell is Bash, which offers:

• Scripting — writing a file of commands to execute together
• Aliases — short nicknames for longer commands
• Variables — storing information for the shell to use

Understanding the Prompt

Example: sysadmin@localhost:~$

• sysadmin → username
• localhost → system name
• ~ → current directory (home directory shorthand)

Commands, Options & Arguments

Basic format: command [options] [arguments]

• Arguments — what the command acts on, e.g. ls /etc/ppp
• Options — modify command behavior, e.g.:
  • ls -l → long listing (permissions, size, etc.)
  • ls -r → reverse order
  • ls -lr or ls -rl → combined options, same result
  • ls -lh → human-readable file sizes (e.g., 11K instead of 10376 bytes)
  • ls -l --human-readable → full-word equivalent option

Note: Linux is case-sensitive — commands, options, and file names must be entered exactly as shown.

#Linux #DevOps #CiscoNetworkingAcademy #LearningInPublic #CommandLine