Cheatsheet for Linux, Git and Markdown

Linux

Basic Commands

Command	Description
ls	Lists all files and directories in the present working directory
ls -R	Lists files in sub-directories as well
ls -a	Lists hidden files as well
ls -al	Lists files and directories with detailed information like permissions,size, owner, etc.
cd ~	Navigate to HOME directory
cd ..	Move one level up
cd	To change to a particular directory
cd /	Move to the root directory
cat > filename	Creates a new file
cat filename	Displays the file content
cat file1 file2 > file3	Joins two files (file1, file2) and stores the output in a new file (file3)
mv file "new file path"	Moves the files to the new location
mv filename new_file_name	Renames the file to a new filename
sudo	Allows regular users to run programs with the security privileges of the superuser or root
rm filename	Deletes a file
man	Gives help information on a command
history	Gives a list of all past commands typed in the current terminal session
clear	Clears the terminal
mkdir directoryname	Creates a new directory in the present working directory or a at the specified path
rmdir	Deletes a directory
mv	Renames a directory

File Permissions

Command	Description
ls -l	to show file type and access permission
r	read permission [4]
w	write permission [2]
x	execute permission [1]
-=	no permission
chown user	For changing the ownership of a file/directory
chown user:group filename	change the user as well as group for a file or directory
chmod 775 filename	change file permissions
chmod -R 660 directory	recursively chmod folder

Reading Files

Command	Description
less filename	view and paginate file
file filename	get type of file
head filename	show first 10 lines
tail filename	show last 10 lines
tail -F filename	show last 10 lines as they change

Compression

Compress

tar -czvf name-of-archive.tar.gz /path/to/directory-or-file

Command	Description
c	Create an archive
z	Compress the archive with gzip.
v	Verbose output shows you all the files being archived and much.
f	Allows you to specify the filename of the archive.

Extract

tar -xvzf name-of-archive.tar.gz

Command	Description
x	Tar can collect files or extract them. x does the latter.
v	Verbose output shows you all the files being extracted.
z	Tells tar to decompress the archive using gzip
f	It must be the last flag of the command, and the tar file must be immediately after. It tells tar the name and path of the compressed file.

User Management

Command	Description
sudo adduser username	To add a new user
sudo passwd -l 'username'	To change the password of a user
sudo userdel -r 'username'	To remove a newly created user
sudo usermod -a -G GROUPNAME USERNAME	To add a user to a group
sudo deluser USER GROUPNAME	To remove a user from a group
finger	Shows information of all the users logged in
finger username	Gives information of a particular user

Networking

Command	Description
ssh username@<ip-address-or-hostname>	login into a remote Linux machine using SSH
put file	upload ‘file’ from local to remote computer
get file	Download ‘file’ from remote to local computer
quit	Logout

Process

Command	Description
bg	To send a process to the background
fg	To run a stopped process in the foreground
top	Details on all Active Processes
ps	Give the status of processes running for a user
ps PID	Gives the status of a particular process
pidof	Gives the Process ID (PID) of a process
kill PID	Kills a process
nice	Starts a process with a given priority
renice	Changes priority of an already running process
df	Gives free hard disk space on your system
free	Gives free RAM on your system

---

Git

Configuration

Set the name that will be attached to your commits and tags

git config --global user.name "name"

Set an email address that will be attached to your commits and tags

git config --global user.email "email"

Enable some colorization of Git output

git config --global color.ui auto

Edit the global configuration file in a text editor

git config --global --edit

---

Create a repository

Create a new local repository

git init [project name]

Clone a repository

git clone git_url

Clone a repository into a specified directory

git clone git_url my_directory

---

Make Change

Show modified files in working directory, staged for your next commit

git status

Stages the file, ready for commit

git add [file]

Stage all changed files, ready for commit

git add .

Commit all staged files to versioned history

git commit -m "commit message"

Commit all your tracked files to versioned history

git commit -am "commit message"

Discard changes in working directory which is not staged

git restore [file]

Unstage a staged file or file which is staged

git restore --staged [file]

Unstages file, keeping the file changes

git reset [file]

Revert everything to the last commit

git reset --hard

Apply any commits of current branch ahead of specified one

git rebase [branch]

---

Remote

Add a git URL as an alias

git remote add [alias] [url]

Show the names of the remote repositories you've set up

git remote

Show the names and URLs of the remote repositories

git remote -v

Remove a remote repository

git remote rm [remote repo name]

Change the URL of the git repository

git remote set-url origin [git_url]

---

Branches

List all local branches

git branch

List all branches, local and remote

git branch -av

Switch to my_branch, and update working directory

git checkout my_branch

Create a new branch called new_branch

git checkout -b new_branch

Delete the branch called my_branch

git branch -d my_branch

Merge branchA into branchB

git checkout branchB
git merge branchA

Tag the current commit

git tag my_tag

---

See Changes

See all changes

git diff

Diff of what is staged but not yet committed

git diff --staged

See changed file names and status only

git diff --name-status

See compact summary of changes

git diff --compact-summary

Tip: Use watch command to keep track.

Temporary Commits

Save modified and staged changes

git stash

List stack-order of stashed file changes

git stash list

Write working from top of stash stack

git stash pop

Discard the changes from top of stash stack

git stash drop

---

Sync

Fetch down all the branches from that Git remote

git fetch [alias]

Merge a remote branch into your current branch to bring it up to date

git merge [alias]/[branch]
# No fast-forward
git merge --no-ff [alias]/[branch]
# Only fast-forward
git merge --ff-only [alias]/[branch]

Transmit local branch commits to the remote repository branch

git push [alias] [branch]

Fetch and merge any commits from the tracking remote branch

git pull

Merge just one specific commit from another branch to your current branch

git cherry-pick [commit_id]

---

Markdown

Basic Syntax

These are the elements outlined in John Gruber’s original design document. All Markdown applications support these elements.

Element	Markdown Syntax
Heading	# H1 ## H2 ### H3
Bold	**bold text**
Italic	*italicized text*
Blockquote	> blockquote
Strike-through	~~The world is flat.~~
Ordered List	1. First item 2. Second item 3. Third item
Unordered List	- First item - Second item - Third item
Code	`code`
Horizontal Rule	---
Link	[title](https://www.example.com)
Image	

Extended Syntax

These elements extend the basic syntax by adding additional features. Not all Markdown applications support these elements.

Table

| Syntax    | Description |
| --------- | ----------- |
| Header    | Title       |
| Paragraph | Text        |

Code Block

Make sure backticks have no space like this ```

` ` `json
{
	"firstName": "John",
	"lastName": "Smith",
	"age": 25
}
` ` `

Tasklist

-   [x] Write the press release
-   [ ] Update the website
-   [ ] Contact the media

More

Element	Markdown Syntax
Footnote	Here's a sentence with a footnote. [^1] [^1]: This is the footnote.
Heading ID	### My Great Heading {#custom-id}
Definition List	term : definition
Highlight	I need to highlight these ==very important words==.
Subscript	H~2~O
Superscript	X^2^