LPI Linux Essentials Quick Tips And Commands
Hey guys! Welcome back to my blog. Instead of posting a DevOps project today (I have another one coming within the next couple days or possibly earlier), I thought why not provide you guys with a Quick Tips And Commands study guide that I put together so that you can pass your own LPI Linux Essentials certification.
I had multiple people email me since posting my LPI LE cert a couple weeks ago saying that they were thinking about taking it themselves so I wanted to share this study guide as a free resource since they are typically pretty expensive….
This study guide was put together using ACloudGuru’s LPI LE course as well as the LPI LE practice test from Udemy. The near 50 Linux commands at the bottom of this study guide were saved from a poster on LinkedIn. I will say however, do not use this as your only resource! You should be in the terminal daily practicing the commands to see what the output would be. I will also strongly encourage you to enroll in a course like the LPI LE course at ACloudGuru or somewhere else to build the Linux foundation before jumping into this study guide if you do not already have a good understanding of Linux and the CLI (command line). I personally am a student at Level Up In Tech that provides all of these resources to build a solid foundation to prepare you for a role as a Jr DevOps Engineer AND the cert is included. You can check out the creator of the bootcamp here. Good luck and I hope this helps you! Send me a message on LinkedIn if it does!
Complete Linux Studyguide
-for permissions rwxrwxrwx- R-4. W-2, and X-1. User is the first set of rwx, group is the second and everyone else is the third
-Gimp is a program on Linux used as a replacement for Adobe photoshop.
-Cloud computing provides new tools to manage IT resources
-tty is a UNIX device name for a physical or virtual terminal connection
-CentOS/RedHat, openSUS, and Debian/Ubuntu are all popular Linux distributions
-Impress is a program on Linux that allows you to use as a replacement for Microsoft Powerpoint
-Cloud computing is the on demand availability of computer system resources, especially data storage and computing power without direct active management by the user
-Ubuntu Linux is derived from Debian
-mv command is used to rename a file on Linux
-A environment variable contains all uppercase letters
-whatis is a command that can be given to find man pages
-the * symbol can be used to represent none, one or multiple characters which is a process known as “Globbing”
-the command rm -rf removes ALL of the files in the directory and subdirectory. rmdir only removes directory if it doesn’t have any subdirectories
-the touch command increases the number of files within a directory
-Recursive directory listing means to include the content of the subdirectories as well
-a case script statement uses a variable and each pattern shown before the right parenthesis is a possible value of that variable.
-the syntax for using gzip is “gzip ____”. A -c for “create” is not needed
-$2 is used to access the second command line argument to a script
-Bzip2 is a command line tool used to compress a single file using the Burrows-Wheeler algorithm and Huffman coding. It only compresses single files and is not a file archiver
-the cat command can be used to display the contents of multiple files to the screen at once
-\d is added to put the date into the prompt of the shell
-specifying 2>/dev/null will filter out the error so that they will not be output to your console. The 2 represents the error descriptor, which is where errors are written to. By default, they are printed on the console.
-/dev/null is the standard linux device where you send output that you want to be ignored
-TCP/IP is a set of standards that underlie most modern network communications at the software level
-/dev/sd_ is a how the hard drives are labeled. A is the first drive, b is the second drive and c is the 3rd
-lo is a network interface that always exists in a linux system
-the /sys virtual filesystem is used to interact with the kernel and system as a whole but not with individual processes
-isofs is the file system for a cd-rom and other optical disc media
-the free command is used to view memory usage on a system and can display the total amount of free space available, the amount of memory used and swap memory in the system and the buffers used by the kernel.
-The top command can also be used to display the memory statistics, processor activity and tasks managed by the kernel in real time
-The GID of 0 is always the root group
-the umask command is used to change the default permission for files and directories at the time of creation
-M is used with useradd to create a new user without a home directory
-when there is “t” at the end of permissions, this means that the t os showing that the directory is golbally writable, but only the owner can delete their own files within the directory
-a sticky bit is a specialized permission bit set on a directory
-chgrp is a command that is used to change group ownership of a file
-the for loop lets you iterate or do over a series of words within a string
-Gnome,KDE and XFCE, Cinnamon, Unity and Mate are all popular linux desktops
-GPL stands for general public license
-Apache is a piece of software that listens for network requests and responds to them
-to store the output a command in a variable, it either needs to be variable_name=$(command) or variable_name=‘command’
-the ? Is a symbol used to represent a single character within the search criteria
-Variable is used as a placeholder for an unknown value in a script, and its value is the calculated or determined when the script is executed
-the standard error (STDERR) is represented by the file descriptor number 2
-to search for lines ending with the given pattern, using grep, pattern$ should be used
-nslookup is a command that can be used to resolve a dns name to an IP address
-the maximum amount of memory for a 32 bit OS is 4b
-the free command shows RAM statistics
-ls -a shows all files including hidden files
-linux file names are case sensitive
-etc/skel contains the files and directories automatically copied over to a new user’s home directory when the account is first created
-etc/passwd is used to define all of the users on a linux system
-w displays a list of a ll logged into the system and what they are doing
-stin (standard in)- 0. Stout (standard out)-1. Sterror (standard error)-2
-etc/shadow stores the actual password in an encrypted format. It basically stores secure user account information and aging/account lockout features
-<< accepts text as INPUT
->> accepts text as OUTPUT
-MySQL is an open source relational database management system
-Raspbian is a Debian based computer for raspberry pi
-virtual appliance is a pre-integrated, self contained system that is made by combining a software application with just enough operating system for it to run optimally on industry standard hardware or a virtual machine
-Echo $PATH will show all of the directories that the shell searches for in programs
-aprpos is a command that searches the man page looking for names and descriptors for a user support
-virtual appliance is a reintegrated, self contained system made by combining a software application with just enough operating system to run optimally on industry-standard hardware or a virtual machine
-Postfix is a software package for a mail server
-the dmseg command is used to show the kernel log messages
-/var/log stores most of Linux log files from the directory tree
-ls -s creates a symbolic link in Linux
-a single linux computer can hold an UNLIMITED amount of user accounts
-The Who command displays the USERNAME, TERMINAL IDENTIFIER, LOGIN DATE and TIME
-A browser is not one of the core technologies of the web
-Red Hat is used as a basis for the creation of Scientific Linux
-A kernel is the core computer program with complete control over everything in the system
-to launch a program from the CLI, you type in the actual program
-echo $ is the command you use to see if your command was successful
-Harddrive is labeled a-z, the portion is labeled as 1–10
-dmesg prints the message buffer of the kernel and system boot time messages
-log files are an important part of diagnosing problems with daemons
-LAMP means the combination of Linux, Apache, MySQL, PHP and other programming languages
-A router serves as the gateway between your internal network and external network
-a sticky bit is a special permission bit set on a file or directory that lets only the owner of the file/directory or the root user delete or rename the file
-id provides information about a users identity, including the names of the groups that the user belongs to
-last command will read from a log file and prints the entries of successful login attempts made by the users in the past. The output such that the last logged in users entry appears on top eep-root tty2 Wed Sep 29 21:11–21:11 (00:00)
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-echo is used to write standard output and only prints variables or character output. NO FILES
-when creating a bz2 compression archive, the archive will have .BZ2 at the end of it. Example-tar cjf archive.tar.bz2 /tmp/archive
-a valid IF statement ends in FI
-Ubuntu 804 LTS is an example of a point or stable release type of distribution
-dmidecode and lshw displays hardware information
-configuration files are stored in /etc
-ipaddrshow and ifconfig displays the IP address of local host
-id cloud_user, groups cloud_user and cat/etc/group | grep cloud_user will all show group membership for cloud_user
-when a symbolic links target is deleted, the link persists and links to targets old location
-chown command changes ownership to an admin
-copyleft/gpl is more restrictive than permissive/bsd
-less and cat will print the contents of a file to the screen
-top command displays running processes, PIDs of running processes, current CPU usage, and load average
-maximum limit for each octet on a IPV address- 255 example 198.168.1.1
-ls -l will display the numeric UID/GID of deleted user
-lshw and demidecode pull information off of the motherboard
-etc/group contains a list of local users and attributes and etc/passwd contains the same
-Creative Commons is an American non-profit organization devoted to expanding the range of creative works available to others
-Quoting is a generic name given to the action or prioritizing shell meta characters from being treated specially by the shell
-read is used to get input from the terminal when a shell script is being run
-. -f can be used to get input from the terminal when a shell script is being run and keeps printing new lines
-export is used to make a shell variable known to subsequently executed programs
-the ability to run command is the most basic feature of a shell script
-a daemon is a program that runs in the background
-GPL must disclose the source code and make any modified versions of the code open source. GPL users CANNOT change any of the OG license terms
-Netstat displays network connections for Transmission Control Protocol, routing tables network interface and protocol statistics
-/dev holds all of the device nodes and drivers in the running kernel
-a hard link contains the data in the target file
-. -ls -d shows information about a directory
- apt, pacman, yum, rpm — package managers depending on your distro (distribution)
- alias — create custom shortcuts for your regularly used commands
- cal — View a command line calendar
- cd — Linux command used to create directories in Linux
- chmod — command to change file permissions
- chown — command for granting ownership of files or folders
- clear — Clear the terminal display
- cmp — allows you to check if two files are identical
- cp — Similar usage as mv but for copying files in Linux
- comm — Combines the functionality of diff and cmp
- dd — majorly used for creating bootable USB sticks
- df — display disk filesystem information
- diff — find the difference between two files
- echo — Print any text that follows the command
- export — export environment variables in Linux
- grep — search for a string within an output
- head — Return the specified number of lines from the top
- ifconfig — display network interfaces and IP addresses
- iptables — base firewall for all other firewall utilities to interface with
- kill and killall — kill active processes by process ID or name
- less — Linux command to display paged outputs in the terminal
- ls — The most frequently used command in Linux to list directories
- man — Access manual pages for all Linux commands
- mkdir — Command used to create directories in Linux
- mv — Move or rename files in Linux
- mount — mount file systems in Linux
- name — Linux command to get basic information about the OS
- passwd- create or update passwords for existing users
- ps — Display active processes
- pwd — Print working directory command in Linux
- rm — Delete files or directories with subdirectories
- rmdir — remove a directory with NO subdirectories
- sort — linux command to sort the content of a file while outputting
- ssh — Secure Shell command in Linux
- service — Linux command to start and stop services
- sudo — Command to escalate privileges in Linux
- touch — Create blank/empty files
- tar — Command to extract and compress files in Linux
- tail — Return the specified number of lines from the bottom
- traceroute — trace all the network hops to reach the designation
- top — view active processes live with their system usage
- ufw — firewall command
- unzip — unzip files in Linux
- useradd and usermod — add new user or change existing users data
- whoami- Get the active username
- wget — direct download files from the internet
- whatis — find what a command is used for
- whereis — locate the binary, source and manual pages for a command
- zip — zip files in Linux
