my-command

Cheatsheets

• Vim

• Customize Bash

Compile C

gcc -o caesar caesar.c -lcs50

Get all branch of repository

git fetch --all && git pull origin '*:*'

Install the download package

sudo dpkg -i package.deb

Display or Check SHA256 checksum

Display and check hash of a file or text

SHA256

• display hash of a sample text "Hello, world"

echo Hello, world| sha256sum

OR

printf Hello, world | sha256sum

• check hash of ubuntu downloaded

cd download_directory && sha256sum ubuntu-9.10-dvd-i386.iso

KECCAK-256 (SHA-3)

printf Hello, world | openssl dgst -sha-256sum

Google Colab

• use from file in google colab

from google.colab import drive
drive.mount('/content/drive/')

Tmux

Zellij

Vim

• Substitude

:[range]s/pattern/replacement/[flags]

• [range]
  • % -> All content
  • 10, 20 -> Line 10-20
• pattern -> RegEx
• replacement -> text

• [flags]

  • g -> All selected by pattern
  • c -> Accept for each replace (confirm)

• for example: replace foo inestead of bar on all content

  Copy code

  vim

  :%s/bar/foo/g
  

Customize vim

• Customize Vim

Git

git clone <repo-url>
  cd <repo>
  git fetch --all
  for branch in $(git branch -r | grep -v '\->');do git branch --track "${branch#origin/}" "$branch"; done

• To push all branches

git push --all origin

OR

git push origin branch1 branch2 branch3 ...

• To commit on the latest commit

git add .
git commit --amend --no-edit

• Show graphically git log

git log --all --decorate --online --graph

• Get spesific branch from repo

git clone --branch=main https://github.com/username/repo.git

• Get spesific commits from repo (for example 01 last commit)

git clone --depth 10 https://github.com/username/repo.git

• Local clone repository (from this path to another path locally)

git clone repo_path

• Show changes by HEAD commit

git diff

OR

git diff HEAD

• Show changes from the last commit with 5 commits before the HEAD

git diff HEAD~5

• Show changes from the last commit with 5 commits befor the HEAD for spacial files

git diff HEAD~5 file

• Git log

• Simple log

  Copy code

  bash

  git log
  

• One line

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  bash

  git log --oneline
  

• Show graphicaly log

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  bash

  git log --graph --oneline
  

• Git stash

• Save current changes to a specific (accessible) location and go to the last commit (tracted files)

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  bash

  git add .
  git stash
  

• Save current changes to stash (tracted & untracted files)

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  bash

  git stash -u
  

• Save current changes to stash (tracted & untracted & ignored [all] files)

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  bash

  git stash -a
  

• Show stash

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  bash

  git stash show
  

• Reverting stash changes (by stash number)

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  bash

  git stash pop stash@{0}
  

• Git Blame

Information about each line of a file

git blame file

• Git Tag (readable name instead of hash name)

• Create tag for this commit

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  bash

  git tag "tag_name"
  

• Assigning a tag to another commit based on hash name

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  bash

  git tag "tag_name" 528a389
  

• Git Reflog

git reflog

• Change last commit

git add file
git commit --amend -m "new commit message"

• Git Clean

• Flags

  • i: intractive
  • f: force
  • d: directory
  • n: file
  • x: ignored files or directories

• remove file in main path (untracted)

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  bash

  git clean -n
  

• remove directory in main path (untracted)

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  bash

  git clean -d
  

• Git Revert

git revert is a Git command that reverses the changes of a specific commit by creating a new commit whithout deleting the history.

git revert <commit-hash>

• Git Reset

git reset resets changes to a previous state ans can modify the commit history.

• Type of git reset

  1. soft(--soft): Moves HEAD to a previous commit, keeping changes staged.
  Copy code

  bash

  git reset --soft <commit-hash>
  

  1. Mixed(--mixed) -> default: Resets HEAD and the staging area but keeps working directory changes.
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  bash

  git reset --mixed <commit-hash>
  

  1. Hard(--hard): Deletes all changes from history, staging area, and working directory( irreversible!).
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  bash

  git reset --hard <commit-hash>
  

• Git rm

git rm removes files from the working directory and staging area. (Use git commit to apply the changes permanently)

Usage

• Remove a file and stage the deletition.

  Copy code

  bash

  git rm <file>
  

• Remove from Git but keep it locally.

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  bash

  git rm --cached <file>
  

• Git Remote

• SSH

  • Generate ssh key
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  bash

  ssh-keygen
  

  Don't share id_rsa

  **You can just share id_rsa.pub

  • Add SSH in locally system
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  bash

  ssh-add path/.ssh/id_rsa
  

  • If you encounter an error while adding SSH, run blow command and follow description.
  Copy code

  bash

  ssh-agent -s
  

  To fun : show keys of a persen added to github or gitlab with bellow trick

  https://github.com/username.keys

  DON'T SAVE Public keys from a person because you give him access to the system.

• Show remote

  Copy code

  bash

  git remote
  

• Set remote

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  bash

  git remote add origin git@github.com:username/repo.git
  

• Git Push

• Push changes after seting up the remote when repository doesn't have this branch (Set up strem)

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  bash

  git push -u origin new_branch
  

• Git Checkout

• Create Branch

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  bash

  git checkout -b branch_name
  

• Change branch

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  bash

  git chekout branch
  

• Git Rebase

• An interactive way to modify commit history, allowing you to edit, reoeder, squash, or delet commits.

  Command	Short Command	Description
  pick	p	Keep the commit unchanged in history(default).
  reword	r	Allows you to modify the commit messge.
  edit	e	Pauses the rebase process so you can modify the commit (1.g., edit files of add changes).
  squash	s	Merge this commit with the previous commit message unchanged.
  fixup	f	Similar to squash, but it keeps the previous commit message unchanged.
  drop	d	Removes the commit from history.
  exec	x	Runs a shell command during the rebase process.

  Copy code

  bash

  git rebase -i HEAD~n
  

• Git Merge

• Merge two branch (branch1 with main)

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  bash

  git checkout main
  git merge branch1
  

• Git Branch

• Create branch

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  bash

  git switch -C branch_name
  

  OR

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  bash

  git checkout -b branch_name
  

• To check status of the commits

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  bash

  git branch --verbose
  

• Show list of branches

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  bash

  git branch
  

• Remeove branch

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  bash

  git branch -d branch_name
  

• Git Cherry Pick

• cherry-pick: Select specific commit from another branch and applies them to the current branch.

  Copy code

  bash

  git cherry-pick <commit-hash>
  

Linux

• To show information of sytem

w is the shortest linux command.

w

who is similar to w command but shorter.

• Use Ctrl + r to search in the history of last commands.

• To find current path

pwd

• To mount external hard

sudo mount -t ntfs-3g /dev/sdb2 /mnt

• Exteract example.zip in to example/

unzip example.zip -d example

• find file

find [parent-path] -type [type] -iname "name"

find /home -type f -iname "file-*.txt"

• cat & tac

• cat: show file from beginning to end.

  • -n -> number lines
  • -b -> number lines none block
  • -A -> end lines
  • -s -> remove white enter

• tac: show file from end to beginning.

• Change Python version

• if call python run python2

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  bash

  sudo ln -sf /user/bin/python2 /user/bin/python
  

• Changing user with root access

vim /etc/sudoers

user host=(user) command

• go to line #Allow root to run any commands anywhere and added ...

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  bash

  user  ALL=(ALL)    ALL
  

• The user can onlychange their password (passwd command)

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  bash

  user  ALL=(ALL)    /bin/passwd
  

Ubuntu

• Move to monitors

Super + Shift + ⭠ ⭡ ⭣ ⭢

• Move window

Alt + F7 + ⭠ ⭡ ⭣ ⭢ + Enter

• Change size

Alt + F8 + ⭠ ⭡ ⭣ ⭢ + Enter

SSH

• get IP config -> (int 127.23.21.11)

  must be install sudo apt install net-tools

  Copy code

  bash

  ifconfig
  

• ssh to phone (android)

  Copy code

  bash

  ssh u0_aXXX@192.168.X.X -p 8022
  

SSH-KEYGEN

• generate ssh-kegen

ssh-keygen

• Introducing another system's IP and saving it in the current system

sudo vim /etc/hosts

append ip to hosts file

192.168.X.X  other-sys

• easy ssh

ssh u0_aXXX@other-sys

SCP (secure copy)

• copy file test.txt from other sytem to this system (by recursive)

scp -r u0_aXXX@other-sys:test.txt .

User Management

Users

• Adding new user

sudo useradd <username>

• Set password to new user

sudo passwd <username>

• Go to new user

su - <username>

• Logout from user

exit

• Delete user

ps -u <username>

sudo kill -9 <PID>
sudo pkill -u <username>
sudo killall -u <username>

sudo userdel -r <username>

• User defaults

useradd -D

GROUP=100

HOME=/home

INACTIVE=-1

EXPIRE=

SHELL=/bin/sh

SKEL=/etc/skel

CREATE_MAIL_SPOOL=no

LOG_INIT=yes

• Show and edit default useradd config

sudo vim /etc/default/useradd

• Show and edit default configs

sudo vim /etc/login.defs

Groups

• Show all groups

groups

• Add new groups

sudo groupadd <group_name>

• Changing the group of user

sudo usermod -G <new-group> <username>

• Append the user to the supplemental GROUS

sudo usermod -aG <new-group> <username>

• Removing group from user

sudo groupdel <group-name>

Login

• Show logins

loginctl

• Change Age (change time of stay in system)

chage <username>

Can change:

Minimum Password Age [0]:

Maximum Password Age [99999]:

Last Password Change (YYYY-MM-DD) [2025-04-30]:

Password Expiration Warning [7]:

Password Inactive [-1]:

Acount Expiration Date (YYYY-MM-DD) [-1]:

Password Manager

• Unlocking the password of an user

sudo passwd -uf <username>

• Locking the password af an user

sudo passwd -l <username>

• Changing the password with stdin

echo "password" | passwd --stdin <username>

Emmet (HTML-CSS)

HTML

• 📑 Emmet CheatSheet

• Command: a:www.google.com

• Description: Add href to the <a> tag.

• Result:

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  html

  <a href="www.google.com"></a>
  

• Command: a[https://google.com]

• Description: Add href to the <a> tag.

• Result:

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  html

  <a href="https://google.com"></a>
  

• Command: ul<li{example text $}*5

• Description: Add content to multiple <li> tags and repeat them.

• Result:

  Copy code

  html

  <ul>
    <li>example text $</li>
    <li>example text $</li>
    <li>example text $</li>
    <li>example text $</li>
    <li>example text $</li>
  </ul>
  

• Command: ul>li#item$@-43*5

• Description: Inverse the number from 43, and create 5 <li> elements with the inverted number as part of the content.

• Result:

  Copy code

  html

  <ul>
    <li id="item-43">item-43</li>
    <li id="item-42">item-42</li>
    <li id="item-41">item-41</li>
    <li id="item-40">item-40</li>
    <li id="item-39">item-39</li>
  </ul>
  

• Command: table>(thead>tr>th{col$}*4) + (tbody>tr*3>td{row$-$}*4)

• Description: Create a table with automatic content, including a header and body rows with numbered columns and rows.
• Result:
  Copy code

  html

  <table>
    <thead>
      <tr>
        <th>col1</th>
        <th>col2</th>
        <th>col3</th>
        <th>col4</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>row1-1</td>
        <td>row1-2</td>
        <td>row1-3</td>
        <td>row1-4</td>
      </tr>
      <tr>
        <td>row2-1</td>
        <td>row2-2</td>
        <td>row2-3</td>
        <td>row2-4</td>
      </tr>
      <tr>
        <td>row3-1</td>
        <td>row3-2</td>
        <td>row3-3</td>
        <td>row3-4</td>
      </tr>
    </tbody>
  </table>
  

Text

• head

View the first 15 lines of the file

head -n 15 file.txt

• tail

View the last 15 lines of the file

tail -n 15 file.txt

• cat

Show files with line numbers

cat -n file.txt

• grep

• Filter file after line 190 by "ali"

  Copy code

  bash

  grep -A 190 ali file.txt
  

  OR

  Copy code

  bash

  tail -n 40 file.txt | grep ali
  

• Filter file before line 190 by "ali"

  Copy code

  bash

  grep -B ali file.txt
  

• To don't show phrase(for example: filter by ali but does include hadi)

  Copy code

  bash

  grep ali | grep -v hadi
  

• To recursive filter

  Copy code

  bash

  grep -r .py ~/Desktop
  

• egrep

For RegEx

• find exactly a and 2 l

  Copy code

  bash

  egrep 'al{2}' file.txt
  

• find a and minimum 2 l

  Copy code

  bash

  egrep 'al{2,}' file.txt
  

• find a and maximum 2 l

  Copy code

  bash

  egrep 'al{,2}' file.txt
  

• diff

• differente lines in 2 simailar files

  Copy code

  bash

  diff file1.txt file2.txt
  

• cut

remove sections from each lines of files

• Processing stdout ls -lh and get field 5 and 10 and saving into fileinfo.txt

  Copy code

  bash

  ls -lh | cut --delimiter=" " -f 5,10 > fileinfo.txt
  

• tr

translate or delete characters

• lowercase to uppercase (freq -> FREQ)

  Copy code

  bash

  echo 'freq' | tr [:lower:] [:upper:]
  

Phone

• get username

whoami

• get IP

pkg install net-tools

ifconfig

• run ssh in phone

sshd

• set password

passwd

AND

chmode 600 ~/.ssh/authorized_keys

• close ssh

exit

Z-shell

• git alias z-shell

grafical log

gloga

Bash

• > : write
• >> : append
• < : (stdin)

sort < file.txt

• | : pipe (stdin)

cat file.txt | sort

• (stdin)

sort file.txt

• 0 : stdin
• 1 : stdout

• 2 : stderr

• Bash completion

• if bash completion is disable

  Copy code

  bash

  sudo vim /etc/inputrc
  

  chane disable-completion on to disable-completion off or delete this line.

  Copy code

  bash

  set disable-completion off
  

• variables

• show variables

  Copy code

  bash

  env
  

• show variables

  Copy code

  bash

  echo $PWD
  

• define temporary variable

  Copy code

  bash

  export MYVAR=/home/path
  

• define permanently variable

vim ~/.bashrc

Adding variables permanently

# export SYSTEMD_PAGER=
export MYVARFILE=/home/path

apply changes

source ~/.bashrc

• define alias

vim ~/.bashrc

adding alias command

# User specific aliases and function
alias mydir="cd $MYVAR; ls -aF"

• bash history

show all commands

vim ~/.bash_history

run commands from history (for example run command 6)

!6

clear history

history -c
history -w

• bash logout

write stdout of a command or function log whene logout bash (for example)

append stdout of ls -l command into new_log file

vim ~/.bash_logout

# ~/.bash_logout
ls -l >> new_log

• bash profile

similar to bashrc

Bash Scripting

• shebang

#!/bin/bash

• bash scripting check writeable

ls -l

• if not writeable

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  bash

  chmode +x bash_script.sh
  

• run bash script

./bash_script.sh

• comparison operator

• eq: equal

• gt: greater than
• ge: greater equal
• lt: less than
• le: less equal

Comment line in bash scripting

• Single line

# line

• Multy line

: "
  line1
  line2
  line3
  ...
  end line
  "

• Printf formatting

Get Input

• Get input number and store on VAR

echo -n "enter number: "
read VAR

• Get string input

echo "enter name: "
read name

Condition

if [[ condition ]]
then
    commands
elif [[ condition  ]]
then
    commands
else
    commands
fi

For Loop

• Structure

for var in item1 item2 item3
do
  commands
done

• For in the range

for num in {start..end..step}
do
  commands
done

Brake Loop

• Continue

for i in {1..5};do
  if [[ $i == 2 ]];then
    continue
  fi
  
  echo "Number: $i"
done

• Break

for i in {1..5};do
  if [[ $i == 2 ]];then
    break
  fi
  
  echo "Number: $i"
done

While Loop

• Structure

i=0

  while [ Loop break condition ]
do
  commands
  (( i++ ))
done

• Infinite Loop

while :
do
  commands

  loop_break_condition
done

Read File

file=path/file

while read -r line
do
  echo $line
done

Args

• Get Arguments

args=("$@")

echo ${args[0]} ${args[1]}

• All Arguments

echo $@

• Number of Arguments

echo $#

Array

• Make Array

array=("item1" "item2" "item3" "item4")

• Geting the data from array

Use @ to get all elements

Use ! to get index of elements

Use # to get the number of elements

echo "${array[@]}"
  echo "${!array[@]}"
  echo "${#array[@]}"

Function

• Structure

function_name() {
    commands
}

function_name

• Return value

func_name() {
  echo "value"
  return 12
}

func_name

output

value

Use $? to get numeric reterned vale

func_name() {
  echo "value"
  return 12
}

func_name
echo $?

output

value
  12

• Get value from function

func_name() {
  local var="Linux"
  echo $var
}

variable="$(func_name)"

echo "$variable"

• Send argumanet to function

func() {
  echo "hello, $1"
}

func "name"

• Use argv as function argument

func() {
  echo "hello, $1"
}

func $1

output

app_name.sh ali
hello, ali

Database

Mongo DB

1. Install MongoDB
2. Start

sudo systemctl start mongod

1. Enable

sudo systemctl enable mongod

1. Run & Test

mongosh

1. Exit

exit

• Show all database

show dbs

• Create or Connect Database

use my_database

• Create Collecation

db.createCollection("collection_name")

• Show Collections

show collections

• Current Database

db

• Remove Database

db.dropDatabase()

• Remove Collection

db.collection_name.drop()

• Add Data to collection

db.collection_name.insert({
  name: 'ali',
  age: 23,
  salary: 5000
})

• Show all documents of a collection

db.collection_name.find({})

OR

db.collection_name.find({}).pretty()

• Show all documents in a collecation that contain condition

db.collection_name.find({name: "value"})

• Show one field in all document from collecation

db.collection_name.find({condition}, age:1, _id:0)

• Show document with limited results

db.collection_name.find({}).limit(4)

• Show documents and ignored numbers of first result

db.collection_name.find({}).skip(2)

• Show documents with multi conditions

• AND

  Copy code

  mongodb

  db.collection_name.find({age: 25, nmae: "ali"})
  

• OR

  Copy code

  mongodb

  db.collection_name.find($or[{age: 30}, {name: "mahdi"}])
  

• Greater Than or Less Than

  • $gt -> greater than
  • $lt -> less than
  • $gte -> greater than equal
  • $lte -> less than equal
  • $ne -> not equal
  Copy code

  mongodb

  db.collection_name.find({age: {$gt: 15}})
  

• Update document

db.collection_name.update({condition}, {$set:{age: 43}})

• Remove Objects contains similar values

db.collection_name.remove({column:value})

• Remove spacial objects

db.collection_name.remove({_id: ObjectId("shaID")})

Jupyter Notebook

• Write and create file by jupyter

%%writefile file.txt
this is first line from  content to write into the file
this is second line for writing into file.
...
this is last line to write into the file.

Python

• Precendence & Associativity of Arithmetic Operators

• Tips

  • The output of division in Python is decimal number.
  Copy code

  py

  30 / 2
  
  >>> 15.0
  

  • Write large numbers in Python for convenience with underescores
  Copy code

  py

  1_000_000_000
  >>> 1000000000
  

• Get and remove last value from list

lst = ["Ali", "Mohammad", "Mahdi"]
name1 = lst.pop()

print(name1)
>>> Mahdi

print(name1 is lst)
>>> False

print(lst)
>>> ['Ali', 'Mohammad']

• Infinite Loop

while True:
    if 2 < 3:
        print("runing")
    break

OR

while 1:
    if 2 < 3:
        print("runing")
    break

Numpy

• Get All rows and columns from a matrix

import numpy as np

arr = np.array([
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
])

print(arr[...])

>>> array([[1, 2, 3],
       [4, 5, 6],
       [7, 8, 9]])

Windows

• Write text into a file by CMD

  HINT: Use Ctrl + z to end writing and copying into the file.

copy con file.txt
This is my text for copying to file.
this is seconde line for copying to file.
...
...
...
this is a last line to copeing into file.
^Z

• Read content a file in CMD

copy file.txt con

output

This is my text for copying to file.
this is seconde line for copying to file.
...
...
...
this is a last line to copeing into file.

• Delet file by CMD

del file.txt