CentOS Linux Administration

Master absolute and relative paths, learn your present working directory with pwd, and identify file types: regular files, directories, executables, symbolic links, and device files using the file command.

Learn to create files and directories in CentOS with touch and mkdir, including -p for nested structures. Inspect permissions, ownership, and timestamps with ls -l, and view contents with cat.

Copy, move, rename, and remove files and directories using cp, mv, rm, and rmdir, with recursive options and interactive prompts (-i) as needed.

Learn how to view and set file and directory attributes on CentOS using lsattr and chattr, including append, immutable, and synchronous flags that restrict delete, modify, or rename.

Learn to use the find command to locate files and directories across a directory tree using criteria like name, permissions, size, and type, and to perform actions on matches.

Learn to use the find command to locate files and directories. Use -exec for commands like chmod 644, delete files, and find empty or hidden files and directories by type.

Learn to use the find command to locate files by modification times (mtime) and access times (atime), by size with greater or lesser thresholds, and by type, including -exec examples.

Install the locate tool on Red Hat Linux, update its database regularly, and use locate for fast, case-insensitive file search while requiring root privileges.

Learn how to manage linux file permissions and access rights, using ls -l to view owner, group, and others, and chmod to add or remove read, write, and execute rights.

Create a directory in your home folder and a file, then view and adjust permissions with chmod, including recursive changes, and manage ownership and group assignments.

Learn to manage file permissions on CentOS Linux by creating and assigning groups, adding users with usermod, and using the setgid bit to ensure new files inherit the directory group.

Learn vim basics with two modes, insert and normal, switch via escape or i, navigate with h j k l and shortcuts w b e, and search and edit efficiently.

Learn Vim basics for CentOS Linux administration: switch between insert and command modes, navigate with h j k l, edit text, and save with w and quit with q.

Learn how to access Vim help from the command line, browse topics, begin typing to filter results, and exit back to your session.

Practice creating and editing a new file in vim by naming it text one, inserting text, exiting insert mode with escape, and saving with wq.

Master vim basics for CentOS administration: navigate with h j k l and 0 $, edit with i a c d cc dd yy, and save with :w or :q.

Master vim motion commands and search to navigate a file, scroll with ctrl-f/ctrl-b, move the line to top/center/bottom, and jump by line with j and k.

Open Vim at a specific line or by search pattern, use read-only mode to protect edits, and recover changes after a crash using Vim's capabilities.

Learn to open multiple files and split windows in vim from the command line, using horizontal and vertical splits, buffers, and status line control to navigate and edit efficiently.

Enable vim's mouse option to work with two files when the mouse is disabled by default, and use control-w to quickly switch between windows.

Learn to navigate vim efficiently by switching between normal and insert modes, using home-row motions (h j k l), word/paragraph navigation, and basic search and exit commands.

Install vim on ubuntu, macOS, or Windows, launch vim, enter insert mode, and navigate text with h, j, k, l, w, B, 0, and $ using numeric multipliers.

Learn basic Vim editing for CentOS Linux administration, including movement, search highlighting, copying and pasting lines, deleting to end of file, and inserting text with append and O commands.

Practice vim navigation with hands-on exercises, learning to move between paragraphs using curly braces and jump to the start, middle, and end of the window, line, and file.

Learn advanced vim navigation and editing, including searching for Python occurrences with n and N, deleting words and lines, deleting to end of line, and using undo, redo, and save.

Learn advanced vim search and replace, copy and insert operations, and line-range substitutions to boost text editing efficiency through practical commands like percent substitute, g, and confirm prompts.

Master vim copy and insert in CentOS linux administration, using y, yy, p, and P to copy and paste, with undo support, and learn :read for inserting file contents.

Master Vim's modal system, navigating with normal and insert modes, to edit text efficiently; learn movement, editing, search and replace, yanking, undo, and the dot command for repeating changes.

Learn Vim basics and advanced text editing, from creating and opening files to deleting, copying, pasting, undoing, and redoing, with visual mode, multi-line edits, and customization.

Practice text editing in vim by creating and editing a file, entering insert mode, deleting, undoing, changing words, moving, appending, searching, yanking, pasting, and commenting with a visual block.

Master vim editing techniques for CentOS administration by practicing block moves, text deletion, and reordering sections, using search, visual selection, and the global command to insert notes.

Master vim editing techniques in practice: deleting lines, substituting scripting with programming, indenting bullet points, copying non-contiguous lines, changing content inside parentheses, and yanking paragraphs for efficient text manipulation.

Learn advanced vim techniques for editing and navigation, including opening files at specific lines, working in multi-window mode, read-only mode, and repeating edits with the dot command.

Navigate and edit files in vim through a hands-on Waymo Linux lesson, create files, open buffers, split windows horizontally and vertically, switch between files, and save changes with :wq.

Master advanced vim techniques for managing multiple files on CentOS Linux administration, using diff split to compare web, db, and cache configs and applying edits across buffers with bufdo.

Explore how bash initializes per user, uses startup and initialization files, and leverages the bash history to recall and edit past commands with history and exclamation marks.

Learn to use grep to search for words or phrases in files, view matching lines, paginate output with more, and count lines, words, and characters with wc.

Learn to use the cat command to read files and standard input, redirect output to new files with the > operator, and concatenate multiple files into one.

Connect the output of the who command directly to sort or wc using a pipe, eliminating temporary files and enabling quick counts of logged on users.

Learn to manage linux processes and jobs, foreground and background execution, using & and the jobs, fg, and the bg commands, suspend with ctrl-z, and kill with pid or %job.

Use top to monitor processes, cpu and memory usage, and swap; filter by user, sort by cpu, time, or memory, adjust refresh, and exit with q.

Master changing your password with the passwd command, entering old and new passwords as prompted. Explore shell and environment variables, including path, how to set and access them.

Master essential special characters and keystrokes used in the CentOS shell, including exclamation mark, slashes, quotes, brackets, underscore, asterisk, and navigation shortcuts like ctrl-a and ctrl-e.

Chain commands in CentOS Linux administration using backgrounding with ampersand, semicolon separators, and conditional operators &&, ||, and ! to control execution with file and cat examples.

Use sed to search and replace text in files, perform in-place edits, and apply global substitutions with the g flag; use awk to print the first field.

Explore advanced sed and awk techniques for editing and viewing files: print ranges, replace text (with case-insensitive options), collapse spaces, and insert blank lines, with pipeline comparisons.

Learn to reboot, exit, and shut down a CentOS system using exit to end sessions, reboot for immediate restart, and shutdown with timing options, highlighting the need for root privileges.

Learn to view and print the current shell aliases, set per-session aliases for commands like ls, persist them in ~/.bashrc, and remove all aliases with unalias -a.

Explore using the watch command to monitor command output and file changes in real time, adjust the refresh interval, highlight differences with -d, and pair with tail for live logs.

Discover how to use sudo to execute commands with root privileges, understand password prompts, and configure granular access by editing the sudoers file with visudo.

Explore how Red Hat Enterprise Linux manages rpm packages, including dependency resolution, package naming conventions, metadata storage, and subscription management via the customer portal.

Learn to manage CentOS packages with the rpm command by querying packages, listing files and configuration or documentation, installing and upgrading, verifying signatures, and resolving dependencies from mounted media.

Install and manage packages on CentOS using rpm commands, handle dependencies, upgrade, freshen, and overwrite or remove packages, and verify integrity with md5 and gpg keys.

View GPG keys with rpm, verify package attributes using rpm -V, and interpret the codes that signal changes to owner, group, permissions, size, and digest.

Explore Yume, the Yellow Dog Updater Modified, a front end to RPM for package management via software repositories, configured via yume.conf with cache, log, gpg, plugins, and obsoletes.

Explore yum's common subcommands, manage repositories, and build a local yum repository from installation media; install packages, search, update, and review history with wrapper tools.

Master the yum package manager in CentOS Linux administration by installing, updating, searching, and removing packages and package groups, using local and remote repositories, and tracking transaction history.

Configure a unique hostname on CentOS, verify with hostname, hostnamectl, uname -n, and nmcli, and apply permanent changes via /etc/hostname or hostnamectl while updating /etc/hosts.

Master IPv4 basics: static and dynamic addresses, 32 bit dot decimal notation, and subnet masks. Use ping and traceroute to diagnose connectivity and explore IP tools, networks, gateways, and DNS.

Master the ip command to view and assign addresses, inspect link and address details with ip link show and ip address show, and explore route management with ip route.

Learn to validate and troubleshoot network configuration using core tools. Use ip to view addresses and routes, ping to test connectivity, and ss or netstat to inspect sockets and services.

Engage in a hands-on practice lab to examine network configuration on CentOS, identify interfaces and addresses, view routing, verify router access, trace to internet, and list listening TCP sockets.

Master nmcli to manage the network manager daemon, devices, and connections in CentOS, creating, activating, and modifying DHCP and static configurations, viewing status, and applying DNS and IP settings.

Validate network configuration by listing interfaces with ip link and ip addr show, identifying MAC and IP addresses. Use tracepath or traceroute and ss to verify routing, connectivity, and sockets.

Back up the server connection, configure ip version four addresses, prefix, and gateway with nmcli con mod or ifcfg scripts, then reload to apply changes.

Configure a static IPv4 lab connection on eth2 with 172.25.250.11/24 and 10.0.1.1/24, gateway 172.25.250.254, and DNS 172.25.250.254. Set auto start, update hosts file, reboot, and verify.

Explore how user accounts define security boundaries with root, system, and regular users; use id, ps, and ls to reveal ownership and process information from /etc/passwd.

Configure sudo access on CentOS Linux by editing /etc/sudoers and /etc/sudoers.d to grant users or groups with or without passwords, and compare sudo -i and sudo -s.

Practice gaining superuser access with sudo, switching to root, and inspecting environment variables like home and path; create a test user with sudo privileges.

Create and manage users with useradd, modify with usermod, and delete with userdel, assign home directories and groups, and set passwords while understanding uid ranges.

Create and manage user accounts in CentOS Linux administration by adding operator two, operator three, and operator four; modify details with usermod and set passwords, then delete operator four.

Manage local groups with groupadd, groupdel, and groupmod to create, rename, and delete groups and assign GIDs, including system groups (-r); ensure a group exists before adding users.

Create and verify local groups operators (GID 30,000) and admin, add users with usermod -aG, confirm with id and /etc/group, and grant admin rights via /etc/sudoers.d/admin using sudo.

Learn to manage Linux user passwords with shadow file storage, password aging and expiration policies, and secure verification. Enforce account lock, expiration, and no login shell, and tailor password rules.

Enforce first-login password changes, set password expiration to 90 days, and apply account expiration after 180 days for operator one and other users.

Master local users and groups management by creating the consultants group (gid 40000), granting sudo rights, adding consultant1–3, and enforcing 90-day expiry, 15-day policy for consultant2, and first-login password changes.

Explore how Linux file permissions govern access to files by owner, group, and others, with read, write, and execute rights, where the most specific permissions apply.

Master file and directory permissions with chmod by using symbolic and numeric methods to set read, write, and execute rights for user, group, and others, including recursive changes.

Manage file and directory ownership on CentOS by using chown with owner:group syntax, apply -R for recursive changes, and use chgrp as an alternative for group ownership.

Create a collaborative /home/consultants directory, assign group ownership to consultants, enable group write permissions, and verify multiple users can add and edit consultant1.txt.

Discover how to control default permissions with umask and set special permissions such as setuid, setgid, and sticky to manage group ownership and file access on CentOS Linux.

Explore umask and default permissions by creating a shared tmp directory owned by the operators group, setting the group ID, and validating permanent umask changes to restrict access.

Learn to control file access in a CentOS linux administration lab by creating a shared directory, setting tag docs group ownership, applying setgid, and enforcing a restrictive umask.

Learn to monitor and control Linux processes on a Red Hat Enterprise Linux eight system, using ps and top to view status, resource use, ownership, load average, and process states.

Manage multiple processes started from the same terminal using bash job control, including foreground and background jobs, pipelines, and commands such as jobs, fg, and bg.

Explore job control in CentOS Linux administration by suspending and restarting user processes with a bash script, then manage them using bg, fg, and the jobs command.

Learn to manage Linux processes by sending signals to end user sessions and daemons, using kill, pkill, and killall, and inspect with ps, pgrep, and ps tree.

Analyze Linux load average and identify processes causing high resource use on a server, considering CPU, disk I/O, and network I/O, with tools like uptime and top.

Monitor and manage linux processes using top, create CPU load scripts, and control processes with pkill, kill, and jobs in a multi-terminal session.

Master how systemd controls and monitors network services and daemons on CentOS, using systemctl to manage service, socket, and path units, view status, and enable at boot.

Learn to manage systemd services on CentOS by listing units, checking status, enabling at boot, and using start, stop, restart, reload, and mask techniques to control daemons.

Learn to access remote command lines securely using ssh with OpenSSH on CentOS Linux. Configure key-based authentication, restrict root and password logins, and manage host key verification and known_hosts.

Configure ssh key-based authentication to enable passwordless login by generating a private and public key pair, copying the public key to remote servers, and optionally using ssh-agent to manage passphrases.

Configure OpenSSH to disable direct root logins and password authentication, enable key-based authentication, and reload sshd to apply changes.

Describe how the system log architecture records events with system journal and syslog, configure journaling and time synchronization with NTP, and navigate /var/log files like messages, secure, cron, and boot.log.

Explore how syslog uses facilities, priorities, and severities, and configure rsyslog rules to route messages to files. Learn to monitor logs with tail and test logging with logger.

Learn to locate and interpret system journal entries with journalctl, filtering by priority and time, and using fields like _pid and _systemd_unit to troubleshoot and monitor the system.

Configure the system journal to persist across reboots by setting the storage parameter to persistent, volatile, or auto in the systemd journald configuration, and verify with journalctl and reboot checks.

Maintain accurate time by synchronizing with NTP via chrony and configuring the correct time zone for precise system journal timestamps.

Learn to configure time zones on a CentOS server, set up an authentication error log, view recent logs, and validate rsyslog with targeted logging and reporting.

Learn to archive and compress files with tar, creating, listing, and extracting archives, using gzip, bzip2, or xz compression. Transfer securely and synchronize local files with remote servers via ssh.

Learn to securely transfer files between systems using OpenSSH tools such as scp and the secure file transfer program (sftp), authenticate with keys or passwords, and perform recursive copies.

Schedule deferred tasks on CentOS using the at daemon and the add command with flexible timespecs. View, inspect, and manage these jobs via ad queue and add commands.

Schedule recurring user jobs with crontab and manage per-user and system cron files. Learn cron syntax for minutes, hours, day of month, month, and day of week through hands-on exercises.

Learn how to schedule recurring system jobs using system wide crontab files and systemd timer units, ensuring jobs run under the correct authority and survive reboots.

Schedule a daily recurrent system job to count active users with a cron.daily script and log the result, then configure systemd to collect activity data every two minutes.

Enable and configure systemd tmpfiles to create and purge temporary directories, including volatile run and tmp locations, using tmpfiles.d configuration and the systemd-tmpfiles-clean timer.

Configure systemd tmp files to remove unused /tmp files older than five days and purge run momentary files after 30 seconds, with root ownership and 0700 permissions.

Optimize system performance on CentOS by applying tuning profiles with the tuned daemon. Use tuned-adm to switch profiles, monitor activity, and adjust parameters for static or dynamic tuning.

Explore how Linux uses time slicing to schedule multiple processes across CPUs, and manage niceness with nice values, top, and ps, including sched_normal policies.

Apply nice and really nice to manage process scheduling, observe CPU usage across multiple sha1sum processes, determine CPU cores, monitor with ps, pgrep, and jobs, then adjust again with renice.

Learn to interpret and set access control lists (ACLs) on files and directories with getfacl and setfacl, including default ACLs, named users, named groups, mask, and precedence.

Learn to manage access control lists (ACLs) on files and directories using setfacl and getfacl, including add, modify, delete, and mask operations, with recursive and default ACLs for inheritance.

Practice securing a shared directory with ACLs using setfacl to grant the consultants group full access and deny consultant one, with default ACLs so new files inherit permissions.

Learn to create and manage storage partitions, format with ZFS or ext4, mount them, manage swap spaces, and configure persistent fstab mounts for boot.

Create a 1gb partition on /dev/sdb with an ms-dos label using parted, format it with zfs, and configure persistent mounting at /archive via fstab and systemd.

Manage swap space to supplement system ram and create virtual memory using Linux swap partitions. Activate and persist swap with swapon, swapoff, and /etc/fstab for kernel memory management.

Execute partitioning on a new disk in CentOS administration, create a 2 gb zfs partition mounted at /backup, and configure two 512 mb swap partitions to be enabled at boot.

Learn to create and manage logical volumes, file systems, and swap spaces from the command line using LVM. Extend volumes and adjust volume groups non-destructively.

Extend a volume group by adding a physical volume, then extend the logical volume and resize the file system, with zfs grow fs and resize to fs options.

Extend the logical volume and volume group by adding a new pv, then resize the logical volume and the mounted zfs filesystem, verifying with df and ls commands.

Resize server1 lv1 to 768 MiB and create server1-lv2 128 MiB with a zfs file system mounted persistently at /storage/data2, illustrating LVM concepts like PV, VG, and LV.

Explore managing layered storage with Stratis, creating pools from block devices, provisioning file systems, enabling snapshots, and using thin provisioning and cache and data tiers for flexible, persistent storage.

Create and manage a Stratis pool, add data devices, and deploy a thin provisioned Stratis file system. Verify dynamic growth and access data from a snapshot via mount.

Video uses the K video kernel module and UDS to apply zero block elimination, deduplication, and Lz4 compression, creating video volumes on top of block devices.

This lab teaches implementing advanced storage features on CentOS, including creating thinly provisioned and dynamic Stratis file systems, snapshots, and a virtual data optimizer volume with deduplication and compression.

Learn to configure Stratis storage pools on CentOS, create thinly provisioned file systems, snapshot and mount volumes, and explore deduplication and compression with a virtual data optimizer.

Learn to mount and unmount NFS shares on CentOS, create mount points, use mount and fstab for persistent access, and configure NFS conf for NFS version 4.

Explore configuring and testing NFS on CentOS, including exporting shares, testing with mount, and persisting mounts via fstab using NFS v4.

learn to view and set the default boot target, switch to multi-user, and boot into rescue mode on CentOS Linux using systemctl and bootloader menu techniques.

Learn to reset a lost root password on CentOS via boot-time initramfs, remounting sysroot, switching to a chroot, and using passwd root, then relabel.

Learn to control the boot process in CentOS: reset root password, troubleshoot boot failures, fix fstab and SELinux relabel, and set the default target to graphical.

Master foundational IPv4 networking concepts—tcp/ip four-layer model, ip addressing, subnet masks and cidr, routing tables, and name resolution—through hands-on labs using nmcli and static configurations.

Understand IPv4 addressing, including binary and dotted decimal notation, subnet masks, and classful and classless subnetting, to design networks with proper network and host IDs and default gateways.

Explore IPv4 addressing concepts, including classful versus classless, network and broadcast addresses, and subnet planning for a campus with private, public, and APIPA ranges and NAT basics.

Plan an IPv4 address scheme for Adatum's branch offices, determine device counts and wired versus wireless needs, using /24 subnets from the Toronto pool for Houston, Mexico City, and Portland.

Create a private key with OpenSSL on Red Hat Linux, using RSA 2048, protect with a passphrase, and generate a self-signed X.509 certificate for a server host.

Create and manage a certificate authority with self-signed roots using OpenSSL, generating a 2048-bit private key, a root certificate, and preparing to sign server certificates.

Create a self-signed CA certificate and a server certificate using OpenSSL, generate private keys and CSRs, sign requests, and prepare server and CA directories for testing TLS.

Learn Linux root access security through hands-on practice, check root status with su and sudo, and explore modular sudoers handling per-user and per-role rules.

Learn to lock the root account, escalate privileges with sudo, add a sudo user, and disable root login in sshd_config for secure centos linux administration.

Configure granular sudoers policies to enforce least privilege, shaping sudoers structure, environment controls, and role based access for users and groups, with no password policies and secure path enforcement.

Create a restrictive sudo configuration for the service admin user in sudoers.d to allow passwordless systemctl and journalctl across all servers, while requiring passwords for apt update or dnf upgrade.

Define role-based access control groups for web admins, db admins, and backup admins. Configure sudoers for group members with no-password access and a 60-minute password grace for backups.

Master sudoers file permissions and role-based access validation on CentOS Linux by ensuring root ownership, 0440 permissions, and testing web, db, and backup admin access, including nginx and mariadb actions.

Builds an advanced sudoers setup with per-user defaults and command aliases, enabling input/output logging to secure logs, strict password timing, and denial of dangerous commands for secure users.

Explore environment security in sudoers to prevent privilege escalation by enforcing a clean environment, secure_path, and safe env_keep settings, and deleting dangerous variables like ld_preload.

Demonstrates testing environment variables to reveal privilege escalation risks via ld preload, and shows how sudo env handling and secure_path mitigations through sudoers configuration protect against leakage.

Configure pseudo session management and timeouts in sudoers to secure access in shared environments. Create and test defaults for quick, long, and secure sessions with specific timeouts, using sudo commands.

Analyze effective sudo policies for users and groups in CentOS, inspect allowed commands with sudo -l and -U, and troubleshoot policy mismatches via error redirection.

Remove test users and groups, archive sudoers configurations, and verify sudoers integrity after cleanup to ensure a secure CentOS Linux system.

Explore sudoers best practices and set up a modular configuration repository that enforces least privilege, with example role configurations published on GitHub.

Master Linux root and sudoers security on CentOS by disabling direct root login, hardening SSH, and implementing granular sudoers rules with visudo for least-privilege administration.

Learn to use udevadm to query the udev database, view device attributes, and monitor real time udev events for troubleshooting hardware and writing rules.

Explore how the /proc/interrupts file reveals current IRQ assignments, showing IRQ number, per-cpu handling counts, and interrupt controllers, with real-time monitoring using watch and grep.

Learn to use udevadm to query the udev database, monitor events, and understand device attributes such as kernel name, subsystem, and size, helpful for writing udev rules.

Explore kernel module loading with modprobe, including dependencies and conflicts, and verify with lsmod. Practice loading and removing modules like loop, detaching loop devices with losetup, and troubleshooting with rmmod.

Install the btrfs module and utilities on Red Hat Enterprise Linux, troubleshoot package availability, and manage repositories, subscriptions, and snapd for Snap package manager, using dnf, CodeReady Builder, and EPEL.

Learn to detect usb devices in CentOS Linux administration using lsusb, view detailed info with lsusb -v, monitor changes with watch, and fetch device specifics with udevadm info.

Use dmesg to monitor kernel messages and troubleshoot hardware, with readable timestamps and colorized output, and filter for errors and warnings in real time.

Explore Linux runlevels for maintenance and troubleshooting, from runlevel zero (halt) to runlevel six (reboot), including single-user mode and multi-user with networking, plus systemd rescue.target as the modern equivalent.

Explore the lspci command to view PCI devices, IRQ settings, PCI bus speed, and vendor identification, while noting it omits system battery type and Ethernet MAC address.

Explain how systemd treats manually mounted file systems not in fstab and how systemctl mount sync can create a mount unit from an existing mount, with a usb example.

Learn to filter log entries from 8 a.m. to 8:59 a.m. using grep -E with extended regular expressions on server dot log.

Explore command redirection in CentOS Linux administration by using the greater than operator to redirect left-hand side output to a file, creating or overwriting it.

Learn to rename files by inserting the .back before the .txt extension using a targeted regex substitution, s/TXT$/back.txt/, with practical examples.

Master using the man command to access section 1 manuals for user commands, navigate docs efficiently with specific sections, and read command and configuration file information in CentOS Linux administration.

Explore the ln command, create hard links that share the same inode, and differentiate symbolic (soft) links with practical examples and inode checks.

Master the grep -v option to invert matches and output non-matching lines, using practical log and text-search examples to refine pattern filtering in Linux.

Discover that the mkfs command creates the default ext2 file system when run with only a block device, and verify the type using the file command in a hands-on demonstration.

Explore system v init configuration by examining symbolic links in rc two dot d, and learn how s and k scripts start or stop apache2 at runlevels one and two.

Identify which package owns a given file on Debian systems using dpkg -S, with examples like /etc/debian_version and /bin/bash.

Explore archive manipulation with gzip and tar. Gunzip texts.tgz containing a.txt and b.txt leaves texts.tar, illustrating how gzip, gunzip, and tar work together.

Explore the bios boot sequence, including configurable boot steps and how the bios initiates boot after power on, with the bootloader loading the linux kernel.

Learn how to remove packages with dpkg purge, which deletes both the package and its configuration files, and compare it to dpkg remove through a hands-on htop example.

Explore linux process management with nice levels and the nice command to start a process with modified priority. Note that default nice value is zero, and values range from -20.

Explore bash output redirection techniques on CentOS, redirecting standard output and standard error (1 and 2) with 1>&2 and 2>&1 for combined logs.

Demonstrates how to print the current working directory in bash using the PWD command or the echo ${PWD} variable, highlighting case sensitivity and script usage.

Learn to identify root-owned processes using pgrep, list process IDs with -u and -f, and compare outputs to understand different scopes.

Extract usernames and their login shells from /etc/passwd using cut -d: -f 1,7, then format with column -t -s : for readability.

Discover how the which command searches directories listed in the path environment variable to reveal the full path to the executable, helping troubleshoot Linux systems with multiple installations.

Choose the dpkg -r command to uninstall a package while retaining its configuration files for future installation. Understand that a complete purge removes both the package and its configuration files.

Discover that on system v init-based systems the init process has pid 1, consistently across reboots and run levels, and is the first process responsible for system initialization.

Prevent faulty kernel modules from loading at boot by blacklisting the module in /etc/modprobe.d/blacklist.conf; use modprobe -r for temporary unloads, then reboot to verify.

Learn how to use the Zypper package manager for pattern-based installation, including installing all packages ending in foo with the asterisk wildcard, and performing a dry run.

Learn to save files in vi on unix-like systems by using colon w to write to a named file, then use wq to save and quit.

Extract usernames and primary group IDs from /etc/passwd using cat -d: -f 1,4 /etc/passwd, and practice with related commands like sort, paste, and split.

Learn vi editor reverse search and text manipulation using / and ? for searches, n to next, r to replace, f to move to a character, and s to substitute.

Explains how Ctrl+Z sends the stop signal (Sigstop) to foreground processes, how to suspend and resume with bg/fg, and how Sigint (Ctrl+C) differs from Sigstop in Unix-like systems.

Learn how to use the tee command for command output redirection to display results on screen while saving them to a file, enabling real-time logging, debugging, and monitoring.

Explore the Grub2 standard installation files, including the i386 pc directory and grub.cfg, and understand how the LVM module supports logical volume management within Grub2.

Use the find command to locate files owned by root in /tmp and subdirectories, print results with -print or rely on implicit, and search by -user root or -uid root.

Identify that ext4 reserves 5% of total space for the root user, enabling essential tasks when full and reducing fragmentation, adjustable with the tune to effects command.

Learn to use here documents to input multiline text into Linux commands with cat << delimiter, end-of-file markers, and delimiters like EOT or EOF for multi-line input.

Learn how to use the tune to fs command to set the file system check interval to 200 days on /dev/sda1 for ext2/3/4, balancing boot time and system integrity.

Convert windows line endings to linux by using tr -d '\r' to remove carriage returns from a text file, creating a linux-formatted output such as new list.txt.

Pressing control plus C sends SIGINT, the interrupt signal, allowing a process to catch it and terminate gracefully instead of SIGKILL, a forced termination.

Install grub boot files into the active file systems and the boot loader on the first disk with grub install /dev/sda, using sudo for privileges.

Learn how apt-get dist-upgrade updates all installed packages, handles complex dependencies, and may remove obsolete packages, with practical steps for update, dry-run, and upgrading.

Run rpm --query --all to list all installed packages on an rpm-based system, such as CentOS nine, and browse results with a pager like less.

Learn how to install grub2 into the master boot record on the third hard disk using grub install dev sdc with sudo, noting the target device may vary.

Learn how appending an ampersand to a command runs it in the background of the current shell, freeing the terminal for other tasks, with practical examples.

Regular users can set niceness up to 19 with the nice command, lowering Linux process priority within -20 to 19; only root can set negative niceness to raise priority.

Repair ZFS file system inconsistencies after power outages using zfs repair on an unmounted system, avoiding force mounts or special mount options.

Learn why hard links are limited to one file system and cannot point to files on a different system. The lecture demonstrates creating a hard link and confirms identical inodes.

Identify that man pages are stored in the usr share man directory per the filesystem hierarchy standard, ensuring consistent access by the man command across CentOS Linux systems.

Explore removing directories with special characters in their names using rmdir, with a home-directory path such as ~/\dir, and learn why escaping the backslash matters over relying on quotes.

Learn how the shell processes commands with the type command, distinguishing external commands in /bin from built-ins like cd, with examples such as ls and git.

Learn how to display inode numbers for files on Linux using ls -i and the stat command, and understand how inode metadata helps identify file information.

View the contents of a gzip compressed tar archive using tar z tf archive.tgz to peek inside without extracting.

Explore how the split command divides a large file into smaller segments, using a specified line count, with a practical demonstration on generating split_log files in CentOS Linux administration.

Learn initramfs, a compressed file system archive you can examine when unpacked. The kernel temporarily uses it to mount the real root during boot, with contents later available in /run/initramfs.

Configure yum repositories on Red Hat based Linux systems by distributing repository definitions across multiple files in etc/ume wrappers.d, using base, search, and releasever variables for dynamic URLs.

During boot with system v init, the kernel starts /sbin/init (PID 1), the parent of all processes. Learn how to inspect the init process and its command line.

Search file contents with regular expressions using grep, a tool for Linux administration. Grep represents global regular expression print and supports log analysis, code review, and troubleshooting.

Learn how hard links in backup software improve storage efficiency and speed by reusing inodes to avoid duplicating unchanged files, while noting cross-file-system limitations.

Apply the find command's maxdepth option to limit searches to a specific number of subdirectory levels, preventing deep traversal in nested directories.

Compare Linux containers with traditional virtual machines by examining kernel controlled process isolation, resource management, hypervisor roles, and how containers on the same host share the host kernel.

Explore alternatives to explicit device names in fstab, focusing on label and uuid to reliably mount partitions. Learn why label and uuid improve reliability and maintainability on CentOS Linux systems.

Learn how to paste deleted content below the current line in vi using the lowercase p command, with a practical walkthrough of delete and put operations in CentOS Linux administration.

Identify the six fields of a syntactically correct etc fstab line—device name, mount point, file system type, mount options, dump frequency, and fsck order—used to mount file systems at boot.

Learn to execute shell scripts in the current shell without spawning a subshell using the source command or the dot operator, so environment changes persist.

Explore how a braille display provides a tactile interface, translating digital content into small raised dots for visually impaired users.

Identify that the /etc/passwd file stores a user's primary group and other essential details in colon-delimited fields, and practice locating your own account and its primary group.

Identify valid IPv6 addresses by recognizing eight groups of four hexadecimal digits separated by colons, using 0–9 and A–F, with a single double colon to compress zeros.

Understand that the IPv6 hop limit field decrements at each forwarding router to limit packet lifespan, not static, and it resides in the main header, with multicast values potentially varying.

Learn how the dot forward file routes incoming mail to one or more recipients, with immediate effect, and understand user ownership and permissions in Linux mail management.

Explore IPv4 subnetting with a /28 example, determine the network 203.0.13.64, broadcast 203.0.13.79, and usable hosts 203.0.13.65–203.0.13.78, using 255.255.255.240.

Learn how to obtain the current shell's process ID using the echo $$ command, and understand its role in process management and shell scripting.

Explore DNS resolution on CentOS by configuring resolv.conf with keywords such as search and nameserver, learn about default domain appending, and safely edit the file.

Use the env command to display all environment and shell variables and their values. Export new variables, echo them with a dollar sign, and grep to filter results.

Learn how the /etc/services file maps service names to port numbers and protocols, guiding network tools to use standard ports like http (80), https (443), ssh (22), and ftp (21).

Learn how to use the dig command for DNS debugging, which shows the name server response and query details, including query time, server used, and mx records when requested.

Learn how Linux stores passwords using shadow passwords; the /etc/passwd file shows an x in the password field, signaling that encrypted passwords reside in /etc/shadow and require privileged access.

Locate and edit the SSH client configuration file at /etc/ssh/ssh_config and view host settings. Create a user config at ~/.ssh/config with host and user, then connect with ssh.

Network manager on Linux respects existing configurations by default and can be configured to use the distribution's network interface configuration, avoiding automatic DHCP reconfiguration or disabling untouched interfaces.

Explore file system operators for the test command, including dash a for existence and dash f for regular files, while dash z and dash eq handle strings and numbers.

Use the journalctl since and until parameters to define a precise time window for log queries, viewing entries from a start time onward up to an end time.

Discover the two key network manager states, portal and full connectivity, and learn to observe them with the network manager cli on Linux.

Use lpstat and lpqueue to display and monitor print queue jobs in a Linux environment. Practice checking the current queue and understanding results when no printer is connected.

Use the chage command to modify password expiry information, including minimum and maximum days between changes, last change date, account expiration, and warning period.

Identify the Spice protocol as the virtual machine video output protocol designed for VM graphics output, delivering low latency and high-quality display.

Xorg.conf uses a section based structure where each section starts with a line containing section name and ends with end section line, with options between, not using xml or brackets.

Explore IPv6 characteristics, noting that IPv6 eliminates broadcast addresses and instead uses enhanced multicast, while TCP/UDP port numbers remain unchanged and IPv4 addresses require translation or encapsulation for transition.

Explain which files are read directly by a bash login shell and why .bashrc is not among them, while outlining the startup-file order including /etc/profile, ~/.bash_profile, ~/.bash_login, and ~/.profile.

Learn how nmcli device wifi connect creates and activates a new wifi connection, naming it and handling errors, with practical steps to list networks and disconnect when needed.

Network manager connection types include Ethernet, Wi-Fi, and bridge; learn to list, add, modify, and activate connections with nmcli on Linux.

Configure global shell variables by editing the /etc/profile file to apply variables system-wide at login. The lecture shows exporting a variable and validating it with echo.

Explore how to configure system-wide locale settings using locale.conf, focusing on LC_ALL and LC_TIME to control language, encoding, and time formats; avoid nonstandard variables and understand the need for backups.

Learn how sudo configuration controls user permissions, including no password and password directives that govern commands like kill, id, and fdisk, with root password required for some actions.

Spice enables remote application access, local USB device integration, and downloading and locally installing applications from a remote machine; it does not replace X.Org and cannot upload or run binaries.

Discover how the systemd timer unit schedules tasks through the timer section, using on boot and on calendar directives to trigger its associated service, as shown with hello.service and hello.timer.

Explore bash scripting with a while read loop that processes echo 1-6 through a pipe, assigns to a, b, c, and echoes in reverse to produce 345621.

Learn how the date command in Linux sets the system date and time and formats output, while noting it cannot independently set date, calculate spans, or print calendars.

Identify root-owned setuid files using the find command starting at /, filter by -user root and -perm 4000 to locate elevated-privilege binaries for security audits.

Configure CentOS time zone to Canadian eastern time by creating a symbolic link from /usr/share/zoneinfo/Canada/Eastern to UTC local time with ln -sf, and verify with timedatectl.

Use valid shell script syntax in the dot profile file in a user's home directory, since it is sourced on login; it need not be executable or have a shebang.

Identify the standard https port as 443 for secure encrypted web communication, contrasting with http port 80 and other ports like 25, 8080, and 636, with netstat and curl demonstrations.

Identify how the /etc/group file stores group names and the comma-separated member lists, while noting that it omits home directories, default ACLs, and group descriptions.

Explain that ssh host keys provide the server identity to clients to establish trust and prevent man-in-the-middle attacks. Store the keys in /etc/ssh and use fingerprints to aid verification.

Learn how to assign the output of a command to a shell variable using command substitution, with the correct syntax mydate="$(date)" and the pitfalls of other methods.