Linux & Bash Shell Scripting with Real Networking Examples

Download and install Oracle VirtualBox on Windows, create a centosvm1 with 2 GB RAM and 16 GB dynamic storage, load the CentOS ISO, and configure NAT and shared folders.

Map the CentOS 7 image to the cd-rom, boot the installer, and configure three adapters—host-only 192.168.60.1, internal 192.168.70.10/70.20, and bridged .41/.51—with promiscuous mode for Wireshark.

Demonstrates first login on a CentOS VM in VirtualBox, from starting the VM and accepting the license to logging in as user1 and using su to switch to root.

Begin CentOS installation by selecting language, time zone, and cd-rom source. Configure storage and network, set hostname centos1, and create root and user1 passwords for server with a graphical interface.

Configure CentOS vm network interfaces with nmcli, assign IPs to enp0s3, enp0s8, and enp0s9, test connectivity via ping, and verify DNS and routing. Update the system and install guest additions.

Configure centos virtual machines using cloning and nmcli networking, set bidirectional shared clipboard, create internal networks with IPs and hostnames, and access via ssh with putty.

Explore shell basics, terminal and console distinctions, and how bash and other shells interact with the kernel to control hardware and run commands.

Customize terminal colors and switch shells in Linux using commands like ps and echo. Verify your default shell and bash version, and access manual pages with man bash.

Inspect bash related files and history with ls -lap, -a, and history, and view .bash_history and .bash_logout. Understand login versus non-login shells and the role of /etc/profile and profile.d in configuring the shell.

Explore how interactive non-login shells read .bashrc, distinguish login vs non-login shells via bash_profile, and create aliases in /etc/profile.d, with a note to favor bashrc for aliases.

Explore interactive vs non-interactive shells in bash by using the $- variable and an if statement, and learn to create, grant permissions, and run scripts with vi and chmod.

Explore shell metacharacters and globbing to perform flexible filename matching and command sequencing. Learn how stars, brackets, negation, and semicolons shape powerful one-line commands.

Master metacharacters and special characters in the shell, including pipe, ampersand, dot, backslash, tilde, and hash. Learn redirection and background execution with practical examples using ls and wc.

Explore how shell quotes and escaping govern metacharacters, including single, double, and backtick quotes with the backslash, and how strong vs weak quotes affect command execution.

Demonstrate arithmetical operations in bash using int variables, including addition, subtraction, multiplication, and division with double parentheses, and post-increment and pre-increment in a script.

Learn how to redirect input, output, and errors in bash using >, >>, 2>&1, and &>, with examples like nmcli con show to demonstrate redirection to files and /dev/null.

Create and run a bash script named newping that uses a for loop to ping multiple hosts with ping -c 3, then chmod 755 and run ./newping to test reachability.

Create a Linux backup script with bash, using return value checks, ping health checks, rsync remote backup of /home/user1, and logging to /tmp/backuplog.

Learn to automate backups with crontab and rsync by establishing SSH passwordless authentication between CentOS machines, generating RSA keys, distributing the public key, and scheduling a daily backup.