Operating System: The OS is a resource
manager, software that sits between the user and the hardware, the housekeeper of the machine,
or an extension of the hardware.
Process: A process is formally described as an executing program, process inherits a UID.
UID: The User ID. Each User has one as an identifier
Group: Grouping Users with separate permissions.
Superuser: The highest group users can be a part of!
BASH: The Bourne Again Shell, the most common shell flavors.
Shell: A Shell is the interpreter in UNIX that allows programming a set of actions. The Shell is accessed through the Command Line Interface.
Session: A session in a Terminal Application, is an instance of the terminal program. They are isolated from one another.
cd - Changes directory, you can use this to traverse almost anywhere on the filesystem.
Manual Page: https://man7.org/linux/man-pages/man1/cd.1p.html
cd DIRECTORY> Moves into this directory.cd ..> Moves back a directory.cd /etc/ssh/ssh_config.d/> Moves into ssh_config.d directory
ls - Lists the files within a specific directory.
Manual Page: https://man7.org/linux/man-pages/man1/ls.1.html
ls> shows files in your Current Working Directory.ls -la> shows all files, including hidden ones, with their permissions.ls -a> shows all files, without permission types.ls -la/home/user > shows all files in the /home/user directory.
clear - Clears the whole terminal
Manual Page: https://man7.org/linux/man-pages/man1/clear.1.html
- Basic Syntax:
clear
cat - Prints out the contents of a file to a terminal
Manual Page: https://man7.org/linux/man-pages/man1/cat.1.html
- Basic Syntax:
cat FILENAME
sudo - Acts as root, not root. Allows different commands to be run.
Manual Page: https://man7.org/linux/man-pages/man8/sudo.8.html
- Basic Syntax:
sudo apt update
less - prints first 10 lines of a file.
Manual Page: https://man7.org/linux/man-pages/man8/sudo.8.html
- Basic Syntax:
less FILENAME
grep - Grabs Text
Manual Page: https://man7.org/linux/man-pages/man1/grep.1.html
- Basic Syntax:
grep TEXT FILENAME
cp - The Copy Command. Copy's content of file into another location/file.
Manual Page: https://man7.org/linux/man-pages/man1/cp.1.html
- Basic Syntax:
cp Nicholas.txt Nicholas2.txt
rm - Removes a file.
Manual Page: https://man7.org/linux/man-pages/man1/rm.1.html
- Basic Syntax:
rm FILENAME
pwd - Prints the current directory you are in.
Manual Page: https://man7.org/linux/man-pages/man1/pwd.1.html
- Basic Syntax:
pwd
| - Pipe, runs commands sequentially. A special character, aka an operator. After it detects this symbol, command1 is over, command2 is then executed, and creates a pipeline as an input output.
Manual Page: https://www.redhat.com/sysadmin/pipes-command-line-linux
- Basic Syntax:
COMMAND1 | COMMAND2
chmod - Changes the permissions of a file. There are 3 categories, read write and execute, for User Group, Guest Group, and Other. This can be represented with numbers, and letters. A very complex command.
Manual Page: https://www.man7.org/linux/man-pages/man1/chmod.1.html
chmod +600 FILENAME- This gives read and write to user groups.chmod +r-x FILENAME- Read and execute permissions are applied to all groups with this command.chmod -rwx FILENAME- Removes permissions from all groups.
echo - Can do so much! It either will put the contents of echo into a file or print the content onto the terminal.
Manual Page: https://man7.org/linux/man-pages/man1/echo.1.html
echo "X" > file.txt> inserts X, getting rid of everything else in the fileecho "X" >> file.txt> appends X to the existing file.echo 'blah' > example.txt | cat example.txt> Echo's blah into a new file, example.txt, it then opens using cat and prints content of file to a terminal.
printenv - Printing environment variables for your Unix Shell
Manual Page: https://man7.org/linux/man-pages/man1/printenv.1.html
- Basic Syntax:
printenv
ps - A command that shows processes that are executing in the system.
Manual Page: https://man7.org/linux/man-pages/man1/ps.1.html
- Basic Syntax:
ps
There are a few modes total in Vim, Replace, Command, Insert, Normal, and Visual Mode. It all
is fairly straightforward, as they do mostly what their names suggest.
Normal: Normal is the default mode of Vim. There are commands specific to normal that we
can execute to!
- r replaces characters
- x deletes characters
- u undos edits
Shortcut - Normal: ESC
Insert: Characters typed in will be put on the file like a text editor.
Shortcut - Insert: i OR ESC + i
Command: Write, and exit are found here. Allows us to execute Vim Commands.
Visual: Works as a highlighter, makes selections of text.
Shortcut - v OR ESC + v
Replace: Replace text by writing over it.
Shortcut - R OR ESC + R
By default, Vim starts in Normal Mode.
You must be in Normal Mode to run these commands.
Cut: dd or D. The difference is one goes to the end of line
Copy: yy
Paste: p
Delete: dd
Up: k OR Up Arrow
Down: j OR Down Arrow
Sideways Left: h OR Left Arrow
Sideways Right: l OR Right Arrow
Page Up: CTRL + B
Page Down: CTRL + F
Top: gg
End: G
Start Of Line: 0
End Of Line: $
You must be in Command Mode to run these commands.
Write: :w OR :w NAME_OF_FILE (if first time saving.)
Quit: :q OR :q! OR :qa!
Line Number: :set nu
Search Text: /WORD_TO_SEARCH