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Notes
Operating Systems

----- LESSON OVERVIEW & PRACTICE TIPS -----
  • Recall that CLI is called a $SHELL in Linux and Bash is language that interacts w/it ​
----- LIST DIRECTORIES IN A GUI ----- 
  • In Windows, Filesystems assigned to drive letters i.e. C: or D: or X: 
  • Each Filesystem has a root directory 
----- WINDOWS: LIST DIRECTORIES IN CLI -----
  • powershell.exe supports any command lines in cmd.exe and many more 
 
ls (List Directory): command line in PowerShell to search a directory (PS C:\Users\User_Name> ls C:\) 
 
Parameter: value associated w/command line but not part of command line 
Get-Help ls –Full: command line with -Full parameter in PowerShell has full description of cmdlet and its parameters (PS C:\Users\User_Name> Get-Help ls –Full) 

Get-Help ls –Force: command line with -Force parameter in PowerShell reveals hidden and system folders (PS C:\Users\User_Name> Get-Help ls –Force C:\) 
 
ProgramData: directory used to hold programs installed In program files 
----- LINUX: LIST DIRECTORIES ----- 
  • In Linux, Root Directory denoted by backslash (\) (User@Host-Name:~$ ls \) 
 
/bin: directory in Linux that stores essential binaries or programs, including ls command 
  • /bin similar to Program Files directory in Windows 
/etc: directory in Linux that stores files for system configuration  
/home: personal directory for users that holds documents, pics, etc. 
  • /etc is similar to Users directory in Windows 
/proc: directory in Linux for currently running processes 
/user: directory in Linux for user-installed software and not to be confused with /home directory 
/var: directory that stores system logs and files that change a lot  
 
Flag: similar to Parameter in Windows to specify values for a command 
  • Every command has different flag options depending on program 
--help: flag to see what options avail for a command in Linux (User@Host-Name:~$ ls –help) 
  
-l (List): flag in Linux that shows detailed list of files and folders (Users@Host-Name:~$ ls –l /) 
-a (All): flag in Linux that shows all files in a directory, including hidden files 

  • In Linux, hide file or directory by pre-pending a dot (.) like .i_am_hidden 
  • Remember -–help flag shows info on how to use command while man command shows Man Pages of command
----- WINDOWS: CHANGING DIRECTORIES IN THE GUI ----- 
Absolute Path: path that starts from your main directory 
Relative Path: path that starts from your current directory 
  • Absolute and Relative Paths aren't important in the GUI but are in the CLI
----- WINDOWS: CHANGING DIRECTORIES IN THE CLI ----- 
Prompt: shows/tells you your current directory in PowerShell 
pwd (Print-Working Directory): command in PowerShell that shows you what directory you’re currently in (PS C:\Users\User> pwd) 
cd (Change Directory): command in PowerShell that changes directory you're in (PS C:\Users\User> cd) 
  • cd command in PowerShell can have a Relative or Absolute Path 
..: command in PowerShell that takes you up 1 level from where you are currently (PS C:\Users\User> cd ..) 
cd ~: command in PowerShell for shortcut to path of your home directory 
Tab Completion: rotates thru directories or files in a command line in PowerShell 
----- LINUX: CHANGING DIRECTORIES IN BASH ----- 
pwd (Print-Working Directory): same as in Windows, but remember forward slash (/) 
cd (Change Directory): same as in Windows, but remember forward slash (/) 
~: same as in Windows, but remember forward slash (/) 
Tab Completion: same as in Windows but shows all options at once  
----- WINDOWS: MAKE DIRECTORIES IN THE GUI, CLI ----- 
mkdir (Make Directory): command line in powershell.exe to create a new directory (PS C:\Users\User> mkdir Folder-Name) 
  • In mkdir, use hyphens, back ticks (`), or quotes for files/folder names, b/c PowerShell doesn't interpret spaces
----- LINUX: MAKE DIRECTORIES IN BASH -----
mkdir: same as in PowerShell, but use backslash (\) in place of backtick (`) to name files, directories 
----- WINDOWS: COMMAND HISTORY ----- 
history: command in PowerShell for history (PS C:\Users\User> history) 
Ctrl-R: shortcut for history command in PowerShell 
  • In PowerShell, use # plus Tab Completion if an older version doesn't use Ctrl-R as shortcut 
  
  • In PowerShell, each command you use is saved into into special file for history 
 
clear: command in PowerShell that clears output on your screen but not history 
----- LINUX: COMMAND HISTORY ----- 
history: same as in Windows to populate command history
Ctrl-R: same shortcut in Windows to recall BASH history
clear: same as in Windows to clear BASH output but not history 
----- WINDOWS: COPYING FILES, DIRECTORIES ----- 
hotkey: shortcut for some sort of task 
  • In Windows, the hotkey for copy is Ctrl-C and for paste is Ctrl-V 
 
cp (Copy): command in PowerShell for copying
  • In PowerShell, cp command does copy directory but not its content 
  • In the CLI, cp command doesn't copy anything by default unless there are errors 
 
Wildcard (*): character used to select files based on certain pattern (PS C:\Users\User\Documents> *.jpg ~ C:\Users\User\Desktop)
-Recurse: parameter In PowerShell that copies directory, then recurses to do the same for its subdirectories 
-Verbose: parameter in PowerShell that copies each line in the files of a directory (PS C:\Users\User\Documents> 'Bird Pictures' C:\Users\User\Desktop> -Recurse –Verbose) 
----- LINUX: COPYING FILES, DIRECTORIES ----- 
 *: same as in PowerShell for filtering files
-r: flag in Linux for recursive copying of all contents of file or folder (Users@Host-Name:~/Desktop$ cp –r 'Cat Pictures' ~/Desktop) 
  • In Linux, -r is equivalent to –Recurse parameter in Windows 
----- WINDOWS: MOVING & RENAMING FILES, DIRECTORIES ----- 
mv (Move Item): command in PowerShell to move or rename file or folder (PS C:\Users\User\Desktop> mv yellow-document.txt ~\Documents OR PS C:\Users\User\Desktop> mv red-document.txt purple-document.txt) 
----- LINUX: MOVING & RENAMING FILES, DIRECTORIES ----- 
mv (Move Item): same as in Windows for moving or renaming file, folder (User@Host-Name:~/Desktop$ mv yellow-document.txt green-document.txt OR User@Host-Name:~/Desktop$ mv document.txt ~/Documents OR User@Host-Name:~/Documents$ mv *_document.txt ~/Desktop)  
----- WINDOWS: REMOVING FILE, DIRECTORIES ----- 
rm (Remove): command in PowerShell to delete file or document (PS C:\Users\User> rm ~\text-one.txt) 
  • Use rm command in PowerShell w/caution b/c it bypasses Recycle Bin, unlike the GUI 
-Force: parameter in PowerShell to force deletion of systems file you might not have authorization for (PS C:\Users\User> rm no-authorization-to-delete.txt -Force) 
-Recurse: parameter in PowerShell to override prompt warning of deletion of all file or folder content (PS C:\Users\User> rm ~\misc_folder –Force) 
----- LINUX: REMOVING FILES, DIRECTORIES ----- 
rm (Remove): same as in PowerShell for deleting file or document
-r: flag in Linux for recursive removal of all contents of file, folder (User@Host-Name:~$ rm –r misc_folder) 
  • In Linux, -r is equivalent to –Recurse parameter in Windows 
----- WINDOWS: DISPLAY FILE CONTENTS ----- 
  • In Windows, text files default to open in Notepad but you can change that 
  • To change Text Editors in Windows, right-click Properties >> Change 
 
cat (concatinate): command in PowerShell to view contents of file (PS C:\Users\User> cat file-contents.txt) 
  • cat command not the best solution to view file b/c it just dumps all contents onto PowerShell
 
more: command in PowerShell to view contents of a file 1 page at a time (PS C:\Users\User> more very-large-document.txt) 
enter: program in PowerShell to advance slowly thru file contents line by line via cat command 
space: program in PowerShell to advance slowly thru file contents page by page via cat command 
q (quit): program in PowerShell that allows you to leave/return to CLI 
-Head: parameter in PowerShell that glimpses first text of a file via cat command (PS C:\Users\User> cat document.txt -Head XX) -- where XX is the number of lines of the document to display 
-tail: parameter in PowerShell that glimpses last text of a file via cat command (PS C:\Users/User> cat fruit.txt -tail XX) -- where XX is the number of lines of the document to display 
---- LINUX: DISPLAY FILE CONTENTS ----- 
cat (concatinate): same as in PowerShell, but not good at viewing large files (User@Host-Name:~$ cat important-document.txt)  
less: similar to more command in Linux for viewing file content page by page (User@Host-Name:~$ less large-document.txt) 
  • "less" a great tool to view files of any size 
  • "less" used often in Linux by IT Support Specialists 
more: command in Linux that's falling out of favor to the less command 
-g: parameter in Linux that moves to beginning of text file 
-G: parameter in Linux that moves to end of a text file 
/word_search: command in Linux that allow you to search for a word or phrase via the cat command 
q (Quit): command in Linux that allows you to leave less command and go back to $Shell 
head: command in Linux via cat command that's similar to –head parameter in Windows CLE (User@Host-Name:~$ head large-document.txt) 
  • head command in Linux shows first 10 lines of file by default 
tail: command in Linux via cat command that's similar to –tail parameter in Windows CLE (User@Host-Name:~$ tail very-large-document.txt) 
  • "tail" in Linux shows last 10 lines of text in a document by default 
----- LINUX: MODIFYING TEXT FILES ----- 
nano: command in Linux for a light text editor available on most distributions (User@Host-Name:~$ nano file_name.txt) 
^X (Ctrl-X): option in nano program in Linux to return to $Shell or save your work 
SHORTHAND FROM HERE ON                     SHORTHAND FROM HERE ON
----- WINDOWS POWERSHELL ----- 
Get-Help: recall that this a cmdlet in PowerShell to get more info about other cmdlets 
ls (List Directory): recall that this a command in PowerShell (and Linux) to see details about command in use 
Get-Alias: cmdlet in PowerShell to find alias of a command, cmdlet 
  • Files and subdirectories aren't the same thing and can both be children of a directory 
  • PowerShell commands are long, descriptive, and understandable, but aliases are shorter 
 
cmd.exe: Windows CLI from MS-DOS days, but can be run b/c of backward compatibility  
dir: command in cmd.exe that's the equivalent to Get-ChildItem and ls in PowerShell) 
/?: parameter in cmd.exe that's the equivalent to Get-Help in PowerShell
----- WINDOWS: SEARCHING WITHIN FILES ----- 
(Windows Search Service: service that indexes files on your computer based on a schedule, then stores list and properties in a database 
  • Windows Search Service is time-consuming and resource heavy, so it's often disabled or not installed on many Windows servers 
  • Windows Search Service has its settings in Control Panel or search "Indexing Options" in Start Menu 
  • All Home Directories in Windows stored in Users folder 
  • Windows Search Services finds files by name, path, modify date, etc. but not by words 
Enable Windows Search Service: Start >> Internet Options >> Advanced >> File Types >> Index Properties and File Contents 
 
  • NotePad++ an alternative to Windows Search Service (^Shift+F) 
 
Select-String (SLS): cmdlet in PowerShell to search words or strings of characters (PS C:\Users\User> Select-String cow ranch_animals.txt) 
  • Example output of ranch_animals.txt:1:cow chicken horse, where "1" is the line of text 
Regular Expressions: pattern-matching language in Windows to describe complicated language 
  • Search multiple files of directory w/pattern matching (PS C:\Users\User> Select-String cow *.txt) 
  • Necessary that IT Support able to find a string in a file or set of files 
 
-Filter: parameter in PowerShell to filter results for file names matching a pattern (PS C:\Users\User> ls 'C:\My Vacation Pics\' -Recurse -Filter *beach) 
* (Asterisk): argument in PowerShell to match anything 
.exe: extension for executable files in Windows ​
​----- WINDOWS: SEARCHING WITHIN DIRECTORIES ----- 
-Filter: parameter in powershell.exe that filters results for file names matching a pattern 
* (Asterisk): argument in powershell.exe to match anything 
.exe: file extension for executable in Windows ​​​
----- LINUX: SEARCHING WITHIN FILES ----- 
grep: command in Linux equivalent to Select-String in PowerShell (User@Host-Name:~$ grep cow ranch_animals.txt OR User@Host-Name:~$ grep cow *_animals.txt) 
----- WINDOWS: INPUT, OUTPUT, AND THE PIPELINE ----- 
echo: command alias in PowerShell for Write-Output for displaying output onto screen  
I/O Streams (Input/Output Streams):  
  • I/O Streams the reason every Windows process or PowerShell command can generate an output following an input 
  • Each process in Windows has three different I/O Streams: stdin (Standard In), stdout (Standard Out), and stderr (Standard Error) 
>: redirector operator in PowerShell overwrites existing file or creates one if it doesn't exist (PS C:\Users\User> echo meow > cat.txt) 
>>: redirector operator in PowerShell that appends output to existing file rather than overwrite it (PS C:\Users\User> echo meow >> cat.txt)
| (Pipe Operator): operator in PowerShell that sends one command's stdout Stream to stdin Stream of another (PS C:\Users\User> cat document.txt | Select-String shhh > shhh_document.txt) 
stderr: redirector operator in PowerShell (PS C:\Users\User> rm you_cant_open_this_secure_file 2> error_message.txt, where 2 is stdout Stream numbered by default) 
1: stdout 
2: stderr 
$null: variable in PowerShell that's a black hole for redirection (PS C:\Users\User> rm you_cant_open_this_secure_file 2> null$)  
  • See Get-Help about_redirection in PowerShell for more info on redirection
----- LINUX: INPUT, OUTPUT, AND THE PIPELINE ----- 
  • Like PowerShell, Linux has three I/O Streams of stdin, stdout, stderr   
stdout: same as in powershell.exe (User@Host-Name:~/Desktop$  echo meow > cats.txt AND User@Host-Name:~/Desktop$ echo meow >> cats.txt) 
stdin (<): same as in PowerShell (User@Host-Name:~/Desktop$ cat file_input OR User@Host-Name:~/Desktop$ cat input_file.txt)  
  • As in PowerShell, stderr denoted by 2> (User@Host-Name:~/Desktop$ ls /dir/fake_dir 2> error_output.txt)  
  • /dev/null: same as null$ in PowerShell (User@Host-Name:~$ less /var/log/syslog 2> /dev/null)
  • Remember that 2> in Linux the redirect operator that filters out error messages  
| (Pipeline): same as in PowerShell to channel output of one command into input of another (User@Host-Name:~/Desktop$ ls –la /etc | grep bluetooth) 
----- WINDOWS & LINUX ADVANCED NAVIGATION ----- 
  • Recall that Regular Expressions used to do advanced pattern-based selection 
----- WINDOWS: DISPLAY FILE CONTENTS -----
  • In Windows, text files default to open in Notepad but you can change that 
  • To change Text Editors in Windows, right-click Properties >> Change 
 
cat (concatinate): command in powershell.exe to view contents of a file (PS C:\Users\User> cat file-contents.txt) 
  • cat isn't the best solution to view a file b/c it just dumps all the contents onto the PowerShell 
more: command in powershell.exe to view the contents of a file 1 page at a time (PS C:\Users\User> more very-large-document.txt) 
enter: program in powershell.exe to advance slowly thru file contents line by line via the cat command 
space: program in powershell.exe to advance slowly thru file contents page by page via the cat command 
q (quit): program in powershell.exe that allows you to leave/return to the Shell 
-Head: parameter in powershell.exe that glimpses the first text of a file via the cat command (PS C:\Users\User> cat document.txt -Head XX) -- where XX is the number of lines of the document to display 
-tail: parameter in powershell.exe that glimpses the last text of a file via the cat command (PS C:\Users/User> cat fruit.txt -tail XX) -- where XX is the number of lines of the document to display ​​
----- LINUX: DISPLAY FILE CONTENTS -----
cat (concatinate): same as in powershell.exe, but it's not good at viewing large files (User@Host-Name:~$ cat important-document.txt)  
less: command in Linux to view (User@Host-Name:~$ less large-document.txt) 
  • "less" is similar to the "more" command in Windows 
  • "less" is a great tool to view files of any size 
  • "less" is use often in Linux by IT Support Specialists 
more: command in Linux that's falling out in favor of the less command 
-g: parameter in Linux that moves to the beginning of a text file 
-G: parameter in Linux that moves to the end of a text file 
/word_search: command in Linux that allow you to search for a word or phrase via the cat command 
q (Quit): command in Linux that allows you to leave the "less" command and go back to the shell 
head: command in Linux via the cat command that's similar to the –head parameter in Windows CLE (User@Host-Name:~$ head large-document.txt) 
  • "head" in Linux shows you the first 10 lines of a file by default 
tail: command in Linux via the cat command that's similar to the –tail parameter in Windows CLE (User@Host-Name:~$ tail very-large-document.txt) 
  • "tail" in Linux shows the last 10 lines of text in a document by default ​
----- WINDOWS & LINUX ADVANCED NAVIGATION -----
  • Recall that Regular Expressions is used to do advanced pattern-based selection 
----- USERS, ADMINS, AND GROUPS, OH MY! ----- 
  • For easier maintenance, users placed into groups based on level of access; permission; or task​​
----- WINDOWS: VIEW USER & GROUP INFO -----
Computer Management: tool in Windows for Admins and power users 
Windows Domain: network of computers, users, files, multiple machines, etc. added to a central database 
Admin can view any account or computer from any machine in a Windows Domain  

Task Scheduler: submenu under System Tools that lets you schedule programs and tasks 
Event Viewer: submenu under System Tools that lets you view your System Logs 
Shared Folder: submenu of System Tools that shows what folder users on a Windows Domain are sharing 
Local Users and Groups: submenu under System Tools for user and group management 
Performance: submenu under System Tools that monitors resources of your machine like CPU and RAM 
Device Manager: submenu under System Tools to manage devices of your computer i.e. network cards, sound cards, etc. 
 
Services and Applications: menu for programs and services on Windows system 
 
UAC (User Access Control): feature in the GUI to prevent unauth changes to a system 
  • UAC requires an admin to approve changes to a system ​
----- WINDOWS: VIEW USER & GROUP INFO USING CLI -----
Get-LocalUser: command in PowerShell to see list of local users on machine (PS C:\Users\User> Get-LocalUser) 
Get-LocalGroup: command in PowerShell to see list of local groups on machine (PS C:\Users\User> Get-LocalGroup) 
Get-LocalGroupMember: command in PowerShell to see members of local group on machine (PS C:\Users\User> Get-LocalGroupMember Administrators)​
----- LINUX: USERS, SUPERUSERS, AND BEYOND ----- 
Root User: directory created automatically on Linux machine and that has unrestricted access 
  • Don't confuse Root User w/Root Directory (/) 
 
sudo (Superuser Do): command in Linux to run only the current command as Root User (User@Host-Name: sudo cat /etc/sudoers) 
  • sudo equivalent to User Access Control (UAC) in Windows 
  • sudo allows Root privileges for current command only 
 
  • Not good practice to stay logged in as Root User b/c files can be modified or deleted by mistake 
su (Substitute User): command in Linux that lets you switch user and defaults to Root User if none selected (root@Host-Name:~ sudo su -) 
/etc/group: file in Linux to view who can run sudo or to view membership of a group (User@User-Name:~$ cat /etc/group) 
/etc/passwd: command file that contains user info in Linux 
 
How to read a membership file (Linux): 
group-name:x:group-id:users (where x an encrypted password stored elsewhere and "group-id" is what the operating system uses when running task involving a group) 
 
File Explorer: interface program/tool in Windows that manages files and folders in a hierarchical, tree-like structure 
 
  • Storage volumes in Windows represented by any single letter, A-Z (i.e. C:\) 
  • Windows is usually stored on C:\ 
  • Files and folders rooted at C:\ on Windows Virtual Machine ​
----- LINUX: CREATING, MODIFYING AND REMOVING FILES/FOLDERS ----- 
  • File Management in Linux a core skill of an IT Support Specialist 
  • File System: controls how files stored and retrieved on a computer 
  • All files and folders in Linux rooted in a hierarchical tree-like Filesystem at / 
  • Escape special characters like spaces and brackets in Linux w/backslash (\) 
  • Recall that navigation commands like ls in Linux allow you to view contents of your current directory (User@Host-Name:~$ ls /Desktop) 
  • Recall that –l in Linux allows you to view ownership and permission of files and folders in Filesystem (User@Host-Name:~$ ls –l /) 
  • Recall that pwd (Print-Working Directory), like in Windows, allows you to see your location in relation to rest of Filesystem (User@Host-Name:~$ pwd) 
  • Recall that less in Linux similar to cat, but allows you to scroll large input files 

  • Multiple arguments can be created in Linux from mkdir command (User@Host-Name:~$ mkdir  directory_name directory_name2 directory_name3) 
  • -p: option in Linux that creates parent directories from mkdir command if they don't exist 
    -m (Mode): option in Linux that sets permissions of directories from mkdir command 
    -v (Verbose): flag in Linux that copies each line in files of a directory from mkdir command 
  • -v in Linux similar to -Verbose in PowerShell, copying each line in file of a directory 
  • rmdir (Remove Directory): command in Linux to remove empty directories 
  • rmdir in Linux has opposite effect of mkdir  
  • -p: option in Linux that removes empty parent directory from rmdir command (User@Host-Name:~$ rmdir dir1 dir2 dir3 dir4) 
     
    touch: command in Linux to change access and modification times of files or create file w/default permissions (User@Host-Name~$ touch empty_file_with_default_permissions) 
    -c: option in Linux that prevents creation of file from touch command 
     
    cp (Copy): command in Linux that copies files and directories, taking at least one source name and one target name (User@Host-Name:~$ cp /home/user/source_name /home/user/target_name) 
    In Linux, cp target file/directory must have source file/directory (no mismatches)  
  • cp will overwrite pre-existing target files of same name 
  • cp will duplicate pre-existing target directories of same name 
  • mv: command in Linux that moves files, directories into different location, or renames them (User@Host-Name:~$ mv /home/user/source_file /home/user/target_file) 
  • rm: command in Linux to remove a directory w/content (User@Host-Name:~$ rm /home/user/existing_file) 
    -r (Remove): option in Linux to remove directory and its contents recursively from rm command (User@Host-Name:~$ rm –r non_empty_directory) 
  • Use mv command in Linux to move files into current directory (User@Host-Name:~/ home/user/Pets$ mv Dog\ File\ to\ Copy) 
​
  • Recall that grep an ultra-powerful Linux command to search strings and patterns in files and optimized w/different flags and options (User@Host-Name:~$ grep –rw /home/user/Garden -e "Plants")  
-r: option/flag in Linux to search strings or patterns in files recursively from grep command 
-w: option/flag in Linux to match word-for-word a string or pattern in files from grep command 
-n: option/flag in Linux to match a string or pattern only in a line number from grep command 
-e: option/flag in Linux to match a pattern in a file from grep command 
-include/-exclude: option/flag in Linux to include/exclude files in a search from grep command 
-include-dir/-exclude-dir: include/exclude directories in Linux from a search from grep command 

  • Recall that vi and nano are text editors pre-installed in most Linux distributions 
  • nano: command in Linux to run nano text editor (User@Host-Name:~$ nano /file/to/open/in/nano) 
    Ctrl-O: shortcut in Linux to save in nano 
    Ctrl-X: shortcut in Linux to exit nano or help mode in a nano 
    Ctrl-G: shortcut in Linux to get help in nano 

  • Recall that man in Linux allows you to learn more about commands 
  • When performing cp or mv in Linux, you can use a dot (.) to copy or move file to current directory (User@Host-Name:~/home/user/Recipes$ mv /home/user/Blueberry_Pie.txt .) ​
----- WINDOWS: PASSWORDS ----- 
Computer Management: administration of local Windows machine 
Windows Domain: network of computers, files, users, etc. added to a central database for enterprise or organizational administration 
net user: command in PowerShell to change local user passwords (PS C:\Users\User> net user user_name 'user_password') 
  • Asterisk (*) is best practice over written-out password to reset password in PowerShell (PS C:\Users\User> net user user_name *) 
  • Asterisk in place of password in PowerShell prevents password from being logged into your org's central log file 
  • net user a command from MS-DOS days so help also accessible thru /? parameter in CLI 
/logonpasswordchg:yes: parameter in PowerShell for user to change password from the GUI (PS C:\Users\User> net user user_name /logonpasswdchg:yes) ​
----- LINUX: PASSWORDS ----- ​
passwd: command in Linux to change user password (User@Host-Name:~$ sudo passwd user_name) 
/etc/shadow: Linux file that stores passwords are first scrambled 
  • /etc/shadow readable only by Root (/) but scrambled passwords still unreadable by auth users 
-e (Expire): flag in Linux under password command to force user to change password (User@Host-Name:~$ sudo passwd –e user_name)
----- WINDOWS: ADDING, REMOVING USERS ----- 
  • Create new user or delete existing one in Windows thru Content Management (tool) >> Local Users and Groups (folder) >> Right-Click "New User" or "Delete" 
/add: parameter in Windows to create new local user (PS C:\Users\User> net user user_name * /add) 
Get-LocalUser: command in Windows to list local users  
  • You can combine both the creation of new local user and password reset from the GUI (PS C:\Users\User> net user user_name * /add /logonpasswordchg:yes OR PS C:\Users\User> net user user_name 'password' /add /logonpasswordchg:yes) 
Remove-LocalUser: command in PowerShell to remove user (PS C:\Users\User> Remove-LocalUser user_name) 
/del: parameter in PowerShell to remove local user (PS C:\User\User> net user user_name /del) 
  • In Windows, /del parameter an alternative to Remove-LocalUser in the CLI ​​​
---- LINUX: ADDING, REMOVING USERS ----- 
useradd: command in Linux to create local user (User@Host-Name:~$ sudo adduser user_name) 
userdel: command in Linux to delete local user (User@Host-Name:~$ sudo userdel user_name) 
  • In Linux, right-click tool icon at top-right of screen to verify local user deleted or created  ​​​
----- MOBILE USERS, ACCOUNTS ----- 
Primary Account: one-time setup of an account on mobile device 
  • In iOS and Android, Primary Account can synchronize settings and data to the Cloud 
  • In iOS and Android, prior Primary Account used on new device can restore settings, data, and apps backed up to the Cloud 
​User Profile: mobile user account created by Primary Account 
  • User Profile on mobile device contains all preferences, accounts, apps, and can synchronize data to the Clouds 
 
Single-Sign On (SSO): allows apps on mobile device to authenticate login only w/account you're now signed into 
  • SSO allows apps to use your sign-in credentials w/o accessing them  
MDM (Mobile Device Management): system/rules set by org for how mobile device should be configured and used ​​
----- WINDOWS: FILE PERMISSIONS ----- 
Access Control Lists (ACLs): assigns access and permissions in Windows 
Discretionary Access Control Lists (DACLs): a type of Access Control Lists (ACLs) 
System Access Control Lists (SACLs): creates an event log when user accesses file or folder in Windows  
  • In a DACL, each file or folder has 1 owner and 1 or more DACLs 
  • "Permissions" accessible from the "Security" tab in the "Properties" dialogue box when you right-click folder 
Read: Windows permission in the Security Tab that lets you see files, directories, and their contents 
Read & Execute: Windows permission in the Security tab to read a file and run it if an executable 
List Folder Contents: alias Windows permission for "Read and Execute" in the Security tab, but for folder rather than files 
Write: Windows permission in the Security tab that lets you make file changes 
  • In Windows, you can have "Write" access to a file w/o "Read Access" to the same file 
  • In Windows, the "Write" permission allows you to create subdirectories and change files 
Modify: umbrella permission in Windows under the "Security tab that lets you Read, Write, and Execute 
Full Control: Windows permission that allows users or groups to Modify and take ownership to change its ACLs (Access Control Lists) 
ICACLs (Improved Changed ACLs): utility used to view and change Access Control Lists (PS C:\Users\User> icacls \Desktop$) ​
----- WINDOWS ACL ----- 
Access Control List (ACL): a list of Access Control Entries (ACE) in a securable object in Windows 
ACE (Access Control Entries): identifies the trustee in an Access Control List (ACL) and specifies trustee permission  
DACL (Discretionary ACL): contains the ACE and specifies if trustee allowed or denied access to securable object in Windows 
  • If securable object in Windows has no DACL, the system grants full access to the process 
  • If DACL in Windows has no ACE, then system denies the process access to the securable object  ​
----- LINUX: FILE PERMISSIONS ----- 
  • Linux files and folders have 3 permissions: Read, Write, or Execute (a program) 
Syntax of File/Directory Permission 
"-" for File Type or "d" for Directory (1 bit) | Permission of File Owner (3 bits) | Permission of Group (3 bits) | Permission of All Other Users (3 bits) ​
  • A bit is referred to as "set" if It's enabled, like in binary ​
----- WINDOWS: MODIFYING PERMISSIONS ----- 
/grant 'Everyone:(OI)(CI)(R)': parameter in PowerShell that grants all users permission to access a file or directory 
  • In PowerShell, add a single parenthesis if there's a space in the path or if you don't want to interpret the argument as code (PS C:\Users\User> icacls 'C:\Vacation Pictures' /grant 'Everyone:(OI)(CI)(R)') 
  • In the command line (cmd.exe), add double quotes if there's a space in the path (C:\Users\User> icacls "C:\Vacation Pictures" /grant Everyone:(OI)(CI)(R)) 
Guest User: user who can use computer w/o password but account disabled by default 
/grant 'Authenticated Users:(O1)(C1)(R)': parameter in PowerShell that grants authenticated users access to a file or directory (PS C:\Users\User> icacls 'C:\Vacation Pictures' /grant 'Authenticated Users:(OI)(CI)(R)) 
/remove: parameter in PowerShell to delete user permissions (PS C:\Users\User> icacls 'C:\Vacation Pictures' /remove 'Everyone:(OI)(CI)(R)) ​
----- LINUX: MODIFYING PERMISSIONS -----
chmod: command in Linux to change permissions (User@Host-Name:~$ sudo chmod go-rx file_permissions) 
u: permission owner in Linux 
g: permission group in Linux 
o: permission others in Linux 
+/-: option to add/remove permissions in Linux 
Symbolic Format: Linux format of using ugo and rwx to denote permissions in chmod 
Numerical Format: Linux format of using combo of 4/2/1 to denote permission in chmod 
 
4/2/1: numerical equivalent of rwx in Linux 
 
chown (Change Owner): command in Linux to change owner of file/directory (User@Host-Name:~$ sudo chown user_name ownership_file) 
chgrp (Change Group): command in Linux to change group permissions of file, directory (User@Host-Name:~$ sudo chgrp new_file_group old_file_group) 
 
  • Permissions a building block to computer security and IT Support ​
----- WINDOWS: SPECIAL PERMISSIONS ----- 
Simple Permissions: sets of special or specific permissions in Security tab of Properties dialogue box in Windows 
  • When you set "Read" permission, r, on a file, you're setting special permissions like (Properties >> Security >> Advanced) 
IO (Inherit Only): descriptor in Windows for file/directory permissions 
WD: special permission in Windows to create files or write data 
AD: special permission in Windows to create folder or append data 
S: special permission in Windows to synchronize 
  • WD, AD, and S are special permissions in Windows in "Modify Simple Permission," but trustees can't delete but their own files and folders 
CREATOR OWNER: file or folder owner assigned to by dacls in Windows 
  • Local admins and operating system's computer account have full permissions of folder C:\Windows\Temp and all files and folders within 
----- LINUX: SETUID, SETGID, STICKY BIT ----- 
  • ​Recall that sudo used to change files in Linux that Root (/) owns (- rwx -ws --- root tty ....) 
  • SetUID (Set User ID): special permission bit in Linux that allows file to use Root (I) permissions of file's owner (- rws r-- --- 1 root someotheruser ...)   
  • SetUID (s) in Linux grants special Root permissions to file w/o granting Root access 
  • To run file as its owner in Linux, enable special permission SetUID in numerical or symbolic format (User@Host-Name:~$ sudo chmod u+s file_permissions OR User@Host-Name:~$ sudo chmod 4755 file_permissions) 
  • Note that you pre-append "4" (for user Root permission) in Numerical Format for chmod in Linux, but affix s in symbolic format   
  • When "s" a bit within 10-bit permission set, then it allows us to run file w/Root permissions of its owner 
  • SetGID (Set Group ID): permission bit in Linux to run file as member of file group (User@Host-Name:~$ sudo chmod g+s file_permissions OR User@Host-Name:~$ 2755 file_permissions) 
  • Note that you pre-append "2" (granting Root permission to a group) in the Numerical Format for chmod in Linux, but affix s in Symbolic Format (User@Host-Name:~$ sudo chmod g+s some_file OR User@Host-Name:~$ sudo chmod 2751) 
  • Sticky Bit (t): special permission that holds down file/folder so that ugo can write to (modify) it, but only Root or owner can delete file/folder (User@Host-Name:~$ sudo chmod +t folder_permissions OR User@Host-Name:~$ sudo chmod 1755 folder_permissions) 
  • Note that you pre-append "1" (for "others" Root permission) in Numerical Format for chmod in Linux but affix t in Symbolic Format 
  • User access, group access, passwords, and permissions are core concepts of security ​​
----- WINDOWS: CREATING, MODIFYING, AND REMOVING FILE/FOLDER PERMISSIONS ----- 
Usergroup: set of local users in Windows whose permissions you can change all at once 
  • "Everyone" a Usergroup by default in Windows ​
----- LINUX: CREATING, MODIFYING, AND REMOVING FILE/FOLDER PERMISSIONS ----- 
  • Necessary to include sudo w/chmod command in Linux if Root owns file 
 
​​​-ld: flag in Linux equivalent to –l but w/reference to directory 
 
  • Important to remember that chmod in Linux affects only directory when applied to directory and not files within 
  • W/chmod in Linux, you can use "a" argument to "add" special permissions for every user category (ugo) (User@Host-Name:~/home/directory$ a+re example_file) 
  • W/chmod in Linux, "o" argument adds special permissions to "other" users than owner or group (User@Host-Name:~/home/directory/ o+r example_folder/)​​
----- MODULE INTRODUCTION ----- 
  • Installing and maintaining packages a daily task in IT Support 
----- WINDOWS: SOFTWARE PACKAGES ----- 
Software Compiling Tools: what developers use to package software 
Executable File (.exe): what most software in Windows packaged as for computer to execute when run 
  • Executable Files in Windows contain instructions for Windows computer to execute when run 
PE Format (Portable Executable): Windows format to implement .exe file types 
  • .exe files contain instructions for computer to perform, computer code, images the program might use, and maybe an .msi file 
Microsoft Install Package (.msi): guides program called Windows Installer for installation, maintenance, and removal of programs on Windows 
  • Windows Installer uses GUI setup Wizard to help user install program and .msi file to create instructions if user wants to uninstall program 
  • .msi file guides Window Installer and takes care of lots of a program's bookkeeping 
  • Executable File (.exe) usually a starting point to bootstrap Windows Installer but are also standalone custom installers w/no .msi file or Windows Installer 
  • Standalone Executable File (.exe) must contain instructions for Windows to install program 
 
Windows Store: repository introduced in Windows 8 to download and install universal Windows apps 
APPX: package format used by universal Windows apps to package its contents 
  • When running package from the CLI, use /? parameter to see what subcommands package supports  ​
----- LINUX: SOFTWARE PACKAGES ----- 
  • Package types can change depending on Linux distribution 
  • Debian (.deb): packaged as .deb file and used by Ubuntu 
    dpkg (Debian Package): command in Linux to install Debian file (.deb) 
    -i: flag in Linux to install a standalone Debian file (.deb) (User@Host-Name:~$ sudo dpkg -i atom-amd64.deb) 
    -r: flag in Linux to uninstall a standalone Debian file (.deb) (User@Host-Name:~$ sudo dpkg –r atom) 
  • dpkg –l lists Debian packages installed on local machine 
----- MOBILE APP PACKAGES -----  
Mobile Applications: software for mobile operating systems 
App Store App: marketplace and publisher for mobile applications and acts like package manager 
App Store Service: acts like repository for mobile apps 
  • Apps published thru app store signed by developer, often undergo a security review, and approved by store owner 
  • Mobile operating systems configured to trust apps and code signed by publishers it recognizes 
Enterprise App Management: allows org to distribute custom mobile apps developed by or for org 
  • Enterprise Apps w/Enterprise Certificate trusted by devices that install it 
Mobile Device Management Service (MDM): manager for mobile enterprise app installation 
Side-Loading: direct mobile app installation w/o app store   
  • Side-Loading of mobile apps riskier than app stores and used by some app developers  
  • Mobile apps are standalone software packages, so they contain all their dependencies  
  • Mobile apps assigned a specific storage location (cache) for data 
  • Resetting a mobile app to default settings as simple as clearing its cache, which stores anything changed or created ​
----- WINDOWS: ARCHIVES -----
Archive: one or more files compressed into single file 
Package Archives (Zipped File): core or source software files compressed into one file 
  • Package Archives aren't packages at all 
Installing from Source: installing software from source archive i.e. .tar, .zip, and .rar 
7-zip: open-source software for compressing files  
  • To install software from an archive, you must first extract is files from that archive 
  • IT Support Specialists extract files from archives a lot  
  • Pics, music files, software – anything storable in an archive 
Compress-Archive –Path: command in PowerShell to archive files in the CLE (PS C:\Users\User> Compress-Archive –Path C:\Users\User\Desktop\Current_Folder\ ~\Desktop\File_Archive.zip) ​
----- LINUX: ARCHIVES ----- 
7z e (Extract): command in Linux for extracting files with popular open-source compression software 7-zip  
tar: command in most Linux distributions to archive/unarchive files 
  • Remember that different archive types might have different commands ​
----- LINUX TAR COMMAND ----- 
Archive: file containing individual files and info that one or more extraction programs can restore to individual files 
  • Archives can distribute programs, store files, and transmit data ​
----- WINDOWS: PACKAGE DEPENDENCIES ----- 
  • Packages of software oft rely on other code to work 
Having Dependencies: concept of other pieces of software relying on an application to work 
Library: packaging of useful code written by someone else 
DLL (Dynamic-Link Libraries): shared libraries of useful code in Windows for different programs to use 
  • Dynamic-Link Libraries (DLL) divert shared code used by different applications from being loaded into memory 
.msi: many dependencies in a single Windows Installation Package that instructs Windows Installer on how to set up 
  • A given Installation Package has all the dependencies, including DLLs, right in its package 
  • Windows Installer manages dependencies and makes them avail to a program 
Side-by-Side Assemblies (SxS): manages shared libraries and resources in Windows 
C:\Windows\WinSxS: folder where most shared libraries stored in Windows 
Manifest: specification or description of a shared library that application might use to complete a task 
  • Manifest tells Windows to load appropriate library from C:\Windows\WinSxS\ 
  • You can use a Windows Package Manager to help install and maintain Libraries and other dependencies for your installed software 
Find-Package: command for Windows to locate all versions of software from source of package (C:\Users\User> Find-Package sysinternals -IncludeDependencies)  

  • You can write your own cmdlets 
 
Sysinternals Package: tool to help troubleshoot Windows computer (C:\Users\User> Find-Package sysinternals -IncludeDependencies) 
  • PowerShell Gallery a default package source 
​Chocolatey: third-party Package Manager and package repository for Windows 
Register-PackageSource: command in Windows to install a package on Chocolatey (PS C:\Users\User> Register-PackageSource -Name chocolatey –ProviderName chocolatey –Location https://chocolatey.org/api/v2) 

Get-PackageSource: command in PowerShell to verify installation of package (PS C:\Users\User> Get-PackageSource) 
  • Be sure to add – Location to GetPackageSource in Windows so command has source to reference ​
----- LINUX: PACKAGE DEPENDENCIES ----- 
  • Standalone Package Installer like dpkg in Linux is quicker but doesn't install dependencies 
dpkg: package manager for Debian-based Linux systems like Ubuntu 
  • Dependencies in Linux can be Libraries or other packages 
Package Manager: makes package installation and removal in Linux easier ​
----- WINDOWS: PACKAGE MANAGER ----- 
Package Managers: ensures ease of software installation, removal, configuration, and dependency management in Windows 
Chocolatey: third-party Package Manager for Windows that also has a software repository 
SCCM: configuration management tool that integrates w/Chocolatey 
Puppet: configuration management tool that integrates w/Chocolatey 
  • SCCM and Puppet simplifies and automates deployment of Windows software to your computer 
  • Windows Update automates software updates written to it, but you might have to download updated package installer for updated version of software 
 
Install-Package: cmdlet in PowerShell to install software and its dependencies (PS C:\Users\User> Install-Package –Name sysinternals) 
Get-Package: cmdlet in Windows to verify installation of package (PS C:\Users\User> Get-Package –Name sysinternals) 
Uninstall-Package: cmdlet in Windows to remove package (PS C:\Users\User> Uninstall-Package –Name sysinternals) ​
----- LINUX: PACKAGE MANAGER APT ----- 
apt (Advanced Package Tool): package manager for Ubuntu that extends functionality of dpkg, making package installation much easier  
  • apt  (Advanced Package Tool) makes package installation in Ubuntu easier by finding other packages, installing dependencies, removing un-needed packages, etc. (User@Host-Name:~$ sudo apt install gimp OR User@Host-Name:~$ sudo apt remove gimp) 
 
Package Repository: server for applications available to Linux (/etc/apt/sources.list) 
  • Repositories for Linux computer to grab software, add repository or package 
PPAs (Personal Package Archives): special software repository by Launchpad to upload open-source packages to be built and published as an Advanced Package Tool (apt) 
Launchpad: server for open-source software developers to develop, maintain, and distribute software 
  • Developer repositories a safer bet than PPAs (Personal Package Archives) like PowerShell Gallery or Ubuntu b/c they're better vetted 
apt update: command in Linux to update repositories for latest software (User@Host-Name:~$ sudo apt update) 
  • apt update in Linux will update repository, but it won't install packages (User@Host-Name:~$ sudo apt update) 
apt upgrade: command in Linux to install packages (User@Host-Name:~$ sudo apt upgrade) ​
----- LINUX: PACKAGE MANAGER APT ----- 
apt (Advanced Package Tool): package manager in Linux that extends functionality of dpkg, making package installation much easier  
  • apt  (Advanced Package Tool) can find packages in Linux, install dependencies, cleans up non-needed packages, etc. (User@Host-Name:~$ sudo apt install gimp OR PS C:\Users\User> sudo apt remove gimp) 
 
Repository: server for applications 
  • For computer to grab software, add repository or package 
PPAs (Personal Package Archives): special software repository to upload source packages to be built and published as an Advanced Package Tool (apt) repository by Launchpad 
Launchpad: server by Canonical Limited for open-source software developers to develop, maintain, and distribute software 
  • Developers repositories a safer bet than PPAs (Personal Package Archives) b/c it's less vetted than PowerShell Gallery or Ubuntu 
apt update: command in Linux to update repositories for the latest software (User@Host-Name:~$ sudo apt update) 
  • apt update command in Linux will update repository but it won't install packages (User@Host-Name:~$ sudo apt update) 
apt upgrade: command in Linux to install packages (User@Host-Name:~$ sudo apt upgrade) ​
----- WINDOWS: UNDERNEATH THE HOOD ----- 
  • Most Windows software distributed in closed-source packages that don't allow access to its code 
  • Process Monitoring: program provided by Microsoft Sysinternals toolkit to show what installation executable is doing  
  • Closed-source packaging of most Windows software won't allow access to source code, so Process Monitoring useful to check program's actions 
  • Installation Packages that use .msi format still conform to rules and standards for Windows Installer to follow its instructions 
  • .msi files a combo of databases that contain installation instruction files, resources, Libraries, etc. needed by program 
  • Windows Installer creates separate instructions to uninstall a program guided by .msi file 

  • orca.exe: allows non-developers a way to create or edit a Windows Installer Package 
  • Orca part of Windows SDK (Software Development Kit) ​​​
----- WINDOWS: DEVICES & DRIVERS ----- 
Driver: device that helps hardware interact w/operating system  
Device Manager: console that Microsoft uses to group all devices and drivers on computer 
  • Access Device Manager in Windows: Start (menu) >> "devmgmt.msc" OR "This PC" (Right-Click) >> Manage >> Device Manager (option) in Navigation Menu 
devmgmt.msc: one location of Device Manager in Windows found via "Start" menu 
Hardware ID: special ID assigned to device by vendor or computer hardware manufacturer 
  • Windows asks for devices Hardware ID when plugged into computer 
  • Operating Systems use Hardware ID to search for the right Driver 
  • Windows searches for Hardware ID among well-known 1) Drivers 2) Windows Update 3) Driver Store or 4) Driver Software (via Installation Disk) ​
----- LINUX: DEVICE & DRIVERS ----- 
  • In Linux, everything considered a file – including devices 
  • /dev: Linux directory where device files created 
  • Device Drivers aren't stored in /dev directory, but their files created there 
  • Character Device: device in Linux like mouses and keyboards that transmit data character by character 
    Block Devices: devices in Linux that transmit blocks of data like USB drives, hard drives, and CD-ROMs 
    Data Block: unit of data storage 
    /dev/sda OR /dev/sdb OR /dev/sdc: block devices in Linux for mass storage i.e. hard drives and memory sticks 
  • Recall that Linux Kernel is software that handles interaction w/hardware 
  • Kernel Module: extends functionality of Kernel w/o interacting w/its software 
  • Kernel Module for devices that don't have support built into Linux Kernel  
  • Not all Kernel Modules are drivers ​
----- WINDOWS: OPERATING SYSTEM UPDATES ----- 
Security Patch: software in Windows meant to fix a security patch 
Windows Update Client Service: runs in background to download/install updates and patches ​
----- LINUX: OPERATING SYSTEM UPDATES ----- 
  • apt upgrade in Linux doesn't upgrade core operating system i.e. Kernel and other packages 
  • Linux Kernel controls core components of operating system 
uname -r: command in Linux to lookup current Kernel version (User@Host-Name:~$ uname –r) 
apt update: command in Linux to update application sources (User@Host-Name:~$ sudo apt update) 
apt full-upgrade: command in Linux to install new version of Kernel (User@Host-Name:~$ sudo apt full-upgrade) ​
----- SOFTWARE PACKAGING & FILE ARCHIVING IN LINUX ----- 
dpkg –i: command in Linux to install package (User@Host-Name:~$ sudo dpkg -i  /home/folder/downloads/atom-amd64.deb) 
apt install –f: command in Linux to fix missing dependencies from dpkg -i install (User@Host-Name:~$ sudo apt install –f) 
dpkg -s: command in Linux to verify installation of package (User@Host-Name:~$ dpkg -s atom) 
tar –xvf: command in Linux to extract .tar files (User@Host-Name:~/home/my/downloads$ sudo tar -xvf extract_file.tar) 
tar –cvf: command in Linux to archive .tar files (User@Host-Name:~/home/my/downloads$ sudo tar –cvf Colors.tar /Red /White /Blue) 
apt remove: command in Linux to remove file, folder (User@Host-Name:~$ sudo apt remove gimp) ​
----- REMOTE CONNECTION & SSH ----- 
SSH (Secure Shell): protocol implemented by other programs for secure, remote access 
  • An SSH server is a Background process (software), not another hardware computer 
OpenSSH: most popular program to use SSH in Linux 
  • Two ways to establish a remote connection securely is by VPN or SSH Keys 
VPN (Virtual Private Network): private network accessed over Internet 
Related: Operating Systems 3 (Notes)
Related: Operating Systems (Quiz)
Related: Computer Networking 2 (Notes)
Related: Computer Networking 3 (Notes)
Related: IT Fundamentals (Notes)