SYSTEM COMMANDS: System Commands

Topics covered

• Introduction to GNU/Linux

  • Linux operating system
  • Basic overview of GNU/Linux architecture
  • Linux distributions
  • Ubuntu environment
  • Setup Linux in Virtual Machine

• Command Line Environment

  • Terminal and shell
  • Command structure
  • Options and arguments
  • Command execution
  • Command history
  • Basic shell navigation

• Basic Linux Commands

  • pwd — current directory
  • ls — directory contents
  • cd — directory change
  • mkdir — creating a directory
  • rmdir — delete empty directory
  • touch — create/update file
  • cp — copy
  • mv — move/rename
  • rm — delete
  • cat, less, head, tail — viewing file contents

• Hardware Information

  • hwinfo
  • lshw
  • lscpu
  • lsblk
  • free
  • df
  • Battery and memory information

• Operating System Information

  • OS details
  • Kernel version
  • Installed software
  • Package information
  • Version-related commands

• Input and Output Redirection

  • Standard input (stdin)
  • Standard output (stdout)
  • Standard error (stderr)
  • Output redirection using >
  • Append using >>
  • Input redirection using <

Expected skills: Navigate Linux terminal, run basic commands, check system information and use input/output redirection.

Topics covered

• Package Management

  • Package managers
  • Repositories
  • Package installation
  • Package removal
  • Package updates
  • apt update
  • apt install
  • apt remove
  • apt upgrade
  • apt search

• File Types

  • Regular files
  • Directories
  • Symbolic links
  • Device files
  • Special files
  • File identification commands

• File Permissions

  • Read (r)
  • Write (w)
  • Execute (x)
  • Owner, group and others
  • Permission representation
  • chmod
  • chown
  • chgrp

• Symbolic and Numeric Permissions

  • Symbolic mode, such as u+x
  • Numeric mode, such as 755 and 644
  • Permission changes
  • Understanding access modes

• Environment Variables

  • Shell environment
  • $HOME
  • $USER
  • $PATH
  • $SHELL
  • env
  • printenv
  • export
  • Setting and using variables

Expected skills: Managing software packages, understanding file permissions, and configuring environment variables.

Topics covered

• Shell Variables

  • Defining shell variables
  • Reading variable values
  • Local and environment variables
  • Variable expansion
  • Special shell variables

• Prompt Strings

  • Understanding the shell prompt
  • Prompt customization
  • PS1
  • Escape sequences in prompts

• Links and Inodes

  • Hard links
  • Symbolic (soft) links
  • ln
  • ln -s
  • Inode numbers
  • ls -i
  • Differences between hard and symbolic links

• Linux File System

  • Root directory /
  • Important system directories
  • Absolute and relative paths
  • Exploring the root file system
  • Commands such as tree, find and du

• Shell Shortcuts and Output Slicing

  • Command history
  • Tab completion
  • Keyboard shortcuts
  • cut
  • sort
  • uniq
  • wc
  • tr

• Process Management

  • Running processes
  • Foreground and background processes
  • ps
  • top
  • jobs
  • bg
  • fg
  • kill
  • Process IDs (PID)

• Remote Access

  • Local and remote machines
  • SSH basics
  • Connecting to a remote machine
  • Remote shell access

Expected skills: Handle shell variables, create links, manage processes and access remote systems.

Topics covered

• Redirection and Logging

  • Redirecting output to files
  • Append operations
  • Redirecting errors
  • Logging command output
  • Combining input and output redirection

• Pipes

  • Pipe operator |
  • Chaining commands
  • Combining output of one command with another
  • Multi-command pipelines

• Regular Expressions

  • Literal character matching
  • Character classes
  • Wildcards and quantifiers
  • Anchors ^ and $
  • Repetition operators
  • Grouping and alternatives
  • Extended regular expressions

• Pattern Matching with egrep

  • Searching text using patterns
  • Matching multiple patterns
  • Extracting specific lines
  • Case-insensitive matching
  • Counting matching lines
  • Inverting matches

• File Searching with find

  • Searching by file name
  • Searching by file type
  • Searching by size
  • Searching by modification time
  • Combining conditions
  • Using -exec

• Command-Line Editors

  • nano
  • vi / vim
  • emacs
  • Insert and command modes
  • Editing, saving and exiting
  • Basic editor configuration

• Introduction to Bash Scripts

  • Shebang (#!/bin/bash)
  • Creating a script
  • Making a script executable
  • Running a script
  • Basic command sequences

Expected skills: Creating command workflows with pipes and redirection, performing text searches with regular expressions, and writing basic Bash scripts.

Topics covered

• How Shell Scripts Work

  • Shell interpreter
  • Script execution
  • Executable permissions
  • Running scripts through Bash
  • Exit status

• Variables in Scripts

  • Variable declaration
  • Variable expansion
  • Quoting
  • Command substitution
  • Arithmetic expansion

• Command-Line Arguments

  • $0
  • $1, $2, and other positional parameters
  • $#
  • $@
  • $*
  • Passing arguments to scripts
  • Creating reusable commands

• Conditional Statements

  • if
  • elif
  • else
  • fi
  • Numeric comparisons
  • String comparisons
  • File tests
  • Logical operators

• Loops

  • for
  • while
  • until
  • break
  • continue
  • Iterating over files and command output

• Functions

  • Function definition
  • Function calls
  • Parameters
  • Return status
  • Reusing code

• Task Scheduling

  • Startup tasks
  • Periodic tasks
  • Recurring jobs
  • cron
  • crontab
  • Scheduling syntax
  • Basic task automation

Expected skills: Creating automated programs using variables, arguments, conditions, loops and functions in shell scripts.

Topics covered

• Introduction to AWK

  • AWK as a text-processing language
  • Records and fields
  • Field separators
  • Input files
  • Basic AWK syntax
  • awk '{print $1}'

• AWK for Data Processing

  • Selecting specific columns
  • Filtering records
  • Conditional processing
  • Field-based operations
  • Computing sums, averages and counts
  • Processing CSV-like data

• AWK Programming

  • Variables
  • Arithmetic expressions
  • Conditions
  • Loops
  • Built-in functions
  • BEGIN and END blocks
  • Associative arrays

• Regular Expressions in AWK

  • Pattern-based filtering
  • Matching fields
  • Combining patterns and conditions
  • Extracting relevant records

• Introduction to SED

  • Stream editor
  • Line-by-line processing
  • Substitution command s
  • Search and replace
  • Global replacement
  • Address-based editing

• Advanced SED Substitution

  • Regular expressions in SED
  • Capture groups
  • Backreferences
  • Placeholders
  • Deleting and printing selected lines
  • In-place editing

Expected skills: Analyzing structured text files with AWK and performing automated text replacement and transformation with SED.

Topics covered

• Introduction to Make

  • Purpose of the make utility
  • Makefiles
  • Targets
  • Dependencies
  • Recipes and actions
  • Running make commands

• Build Automation

  • Dependency-based execution
  • Updating only required targets
  • Conditional compilation
  • Passing shell variables to Make
  • Automating repetitive build tasks

• File Compression and Packaging

  • tar
  • zip
  • unzip
  • gzip
  • gunzip
  • bzip2
  • xz
  • Creating archives
  • Extracting files
  • Comparing compression formats

• Networking Fundamentals

  • Network interfaces
  • IP addresses
  • IPv4 basics
  • Localhost
  • Private and public IP addresses
  • Intranet concepts

• Ports and Services

  • Port numbers
  • Common services
  • Client-server communication
  • TCP and UDP basics
  • Listening ports

• DNS and Domain Names

  • Domain names
  • DNS resolution
  • Name-to-IP mapping
  • DNS lookup commands

• Network Diagnostics

  • ping
  • ip
  • ss
  • netstat
  • curl
  • traceroute
  • nslookup / dig

• Log Analysis

  • Reading log files
  • Searching errors
  • Combining commands for log analysis
  • Writing small shell-based analysis workflows

Expected skills: Automate build processes with Makefiles, manage compressed archives, and diagnose connectivity with common networking commands.

Topics covered

• RAID

  • Introduction to RAID
  • Data redundancy
  • Handling hardware failures
  • RAID levels and their basic concepts
  • Reliability and storage availability

• Introduction to Version Control

  • Version control systems
  • Git fundamentals
  • Local and remote repositories
  • Git workflow
  • Tracking changes

• Git Commands

  • git init
  • git clone
  • git status
  • git add
  • git commit
  • git log
  • git diff
  • git push
  • git pull
  • git fetch

• Branching and Merging

  • Creating branches
  • Switching branches
  • Merging branches
  • Resolving merge conflicts
  • Managing local and remote changes

• GitHub Collaboration

  • Forking repositories
  • Pull requests
  • Creating and reviewing pull requests
  • Personal access tokens
  • Issues and issue resolution
  • Public repository workflows
  • Private repository collaboration
  • Approval workflows
  • Team-based development

Expected skills: Manage projects through Git and GitHub, use branches and pull requests, and develop code collaboratively with the team.