In the name of God

my-command

Cheatsheets

Terminal

Show tabular file in terminal

bash

column -s, -t < your_file.csv | less -#2 -N -S

-s separate by (,)
t show as a table
less to better display

Compile C

bash

gcc -o caesar caesar.c -lcs50

Get all branch of repository

bash

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

Install the download package

bash

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"

bash

echo Hello, world| sha256sum

bash

printf Hello, world | sha256sum

check hash of ubuntu downloaded

bash

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

KECCAK-256 (SHA-3)

bash

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

Google Colab

use from file in google colab

ipynb

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

Tmux

Activation	Command
Zoomin window	`Ctrl + b` `z`
Zoomout window	`Ctrl + b` `z`
Vertical division window	`Ctrl + b` `%`
Horizontal division window	`Ctrl + b` `"`
Close a window	`Ctrl + b` `x`
Close all windows (close tmux)	`Ctrl + b` `&`
Resize winddows	`Ctrl + b` `⭠ ⭡ ⭣ ⭢`
Show Time	`Ctrl + b` `t`
Number of windows	`Ctrl + b` `q`

Zellij

Activation	Command
Zoomout window	`Ctrl + b + z`
Vertical division window	`Ctrl + b + %`
Horizontal division window	`Ctrl + b + "`
Close a window	`Ctrl + p + x`
Switching bitween windows	`Ctrl + b + ⭠ ⭡ ⭣ ⭢`
Switching bitween windows	`Alt + ⭠ ⭡ ⭣ ⭢`
Resizing window	`Ctrl + n + ⭠ ⭡ ⭣ ⭢`
Rename window	`Ctrl + p + c`
Manager	`Ctrl + o + w`
Change Horizontal/Vertical windows	`Ctrl + Space`
Floating window	`Alt + f`
Resize window
New Tab	`Ctrl + b + c`
Move a pane to another tab	`select pane` `Ctrl + t + []`

Vim

Description	Command	Description
Copy mode	`Ctrl + v`
Copy	`"` + `+` + `y`
Pase	`"` + `+` + `p`
Write on the previuse line	`Shift + o`	for open a line before
Write on the next line	`o`	for open a line after
Append	`Shift + a`	for append text in end line
Append	`a`	for append text after next character
Delete word	`d + w`	for delete word
Delete line	`d + $`	for delete line
Delete line (cut)	`d + d`	for delet line (all)
Move word	`w`	for move on the beginning of words
Move word	`b`	Backward to start of current/previous word
Move word	`e`	for move on the ends of words
Start line	`0`	for move on the beginning of lines
End line	`$`	for move on the ends lines
Delete multi word	`5 + d + w`	for delete 5 words
Undo	`u`	for undo one by one
Undo	`Shift + u`	for undo
Redo	`Ctrl + r`	for redo
Replace	`r`	for replace a letter
Correct	`ce` or `cw` or `c$` or ...	`ce`:Correct and replace untile end of word. `c$`: Correct from the word until end of the line.
Show file info	`Ctrl + g`	Show file name, lines and ...
End of the file	`Shift + g`	go to end file
Start of the file	`g + g`	go to start file
Go to line n	`n + Shift + g`	Go to line n (n is a natural number)
Search	`/`	For search in forwqrd
Search	`?`	for search in backward
Next	`n`	next finded
Previous	`Shift + n`	previous finded
Find maches	`%`	find maches parantesis or brocets or ...

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
vim
```
:%s/bar/foo/g
```

Vim spell checker

Simple

vim

:set spell

Spelling spacial language

vim

set spelllang=en

Persian language spelling

vim

set spelllang=fa

Shortcut to navigate to misspellings

Shortcut	Description
[s	Go to next misspelled
]s	Go to previous misspelled word
z=	Show alternative suggestions
zg	Add word to personal directory
zw	Mark word as misspelled

Customize vim

Customize Vim

Git

bash

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

bash

git push --all origin

bash

git push origin branch1 branch2 branch3 ...

To commit on the latest commit

bash

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

Show graphically git log

bash

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

Get spesific branch from repo

bash

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

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

bash

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

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

bash

git clone repo_path

Show changes by HEAD commit

bash

git diff

bash

git diff HEAD

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

bash

git diff HEAD~5

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

bash

git diff HEAD~5 file

Git log
Simple log
bash
```
git log
```
One line
bash
```
git log --oneline
```
Show graphicaly log
bash
```
git log --graph --oneline
```
Git stash
Save current changes to a specific (accessible) location and go to the last commit (tracted files)
bash
```
git add .
git stash
```
Save current changes to stash (tracted & untracted files)
bash
```
git stash -u
```
Save current changes to stash (tracted & untracted & ignored [all] files)
bash
```
git stash -a
```
Show stash
bash
```
git stash show
```
Reverting stash changes (by stash number)
bash
```
git stash pop stash@{0}
```
Git Blame

Information about each line of a file

bash

git blame file

Git Tag (readable name instead of hash name)
Create tag for this commit
bash
```
git tag "tag_name"
```
Assigning a tag to another commit based on hash name
bash
```
git tag "tag_name" 528a389
```
Git Reflog

bash

git reflog

Change last commit

bash

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)
bash
```
git clean -n
```
remove directory in main path (untracted)
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.

bash

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.
bash
```
git reset --soft <commit-hash>
```
1. Mixed(--mixed) -> default: Resets HEAD and the staging area but keeps working directory changes.
bash
```
git reset --mixed <commit-hash>
```
1. Hard(--hard): Deletes all changes from history, staging area, and working directory( irreversible!).
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.
bash
```
git rm <file>
```
Remove from Git but keep it locally.
bash
```
git rm --cached <file>
```
Git Remote
SSH
- Generate ssh key
bash
```
ssh-keygen
```
Don't share id_rsa

**You can just share id_rsa.pub
- Add SSH in locally system
bash
```
ssh-add path/.ssh/id_rsa
```
- If you encounter an error while adding SSH, run blow command and follow description.
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
bash
```
git remote
```

Set remote

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)
bash
```
git push -u origin new_branch
```
Git Checkout
Create Branch
bash
```
git checkout -b branch_name
```
Change branch
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.

bash

git rebase -i HEAD~n

Git Merge
Merge two branch (branch1 with main)
bash
```
git checkout main
git merge branch1
```
Git Branch

Create branch

bash

git switch -C branch_name

bash

git checkout -b branch_name

To check status of the commits
bash
```
git branch --verbose
```
Show list of branches
bash
```
git branch
```
Remeove branch
bash
```
git branch -d branch_name
```
Git Cherry Pick
cherry-pick: Select specific commit from another branch and applies them to the current branch.
bash
```
git cherry-pick <commit-hash>
```

Linux

To show information of sytem

w is the shortest linux command.

bash

who is similar to w command but shorter.

Use Ctrl + r to search in the history of last commands.
To find current path

bash

pwd

To mount external hard

bash

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

Exteract example.zip in to example/

bash

unzip example.zip -d example

find file

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

bash

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

bash

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

Changing user with root access

bash

vim /etc/sudoers

user host=(user) command

go to line #Allow root to run any commands anywhere and added ...
bash
```
user  ALL=(ALL)    ALL
```
The user can onlychange their password (passwd command)
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
bash
```
ifconfig
```
ssh to phone (android)
bash
```
ssh u0_aXXX@192.168.X.X -p 8022
```

SSH-KEYGEN

generate ssh-kegen

bash

ssh-keygen

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

bash

sudo vim /etc/hosts

append ip to hosts file

bash

192.168.X.X  other-sys

easy ssh

bash

ssh u0_aXXX@other-sys

SCP (secure copy)

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

bash

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

User Management

Users

Adding new user

bash

sudo useradd <username>

Set password to new user

bash

sudo passwd <username>

Go to new user

bash

su - <username>

Logout from user

bash

exit

Delete user

bash

ps -u <username>

bash

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

bash

sudo userdel -r <username>

User defaults

bash

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

bash

sudo vim /etc/default/useradd

Show and edit default configs

bash

sudo vim /etc/login.defs

Groups

Show all groups

bash

groups

Add new groups

bash

sudo groupadd <group_name>

Changing the group of user

bash

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

Append the user to the supplemental GROUS

bash

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

Removing group from user

bash

sudo groupdel <group-name>

Login

Show logins

bash

loginctl

Change Age (change time of stay in system)

bash

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

bash

sudo passwd -uf <username>

Locking the password af an user

bash

sudo passwd -l <username>

Changing the password with stdin

bash

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

Permission Management

Show status of permission of files

bash

ls -l

File and Ownership Permissions Structure

Every file and directory in Linux have three kinds of owers:

User (u): The creator of the file becomes its owner. You can change the ownership later.
Group (g): Users are part of specific groups.Managing users in a multi-user environment involves creating separate groups(e.g., dev team, QA Team, sysadmin team). Group membership simplifies permission management.
Other (o): This group includes all users on the system, even if you're the sole user. Everyone with access to the system belongs to this group.
All (a): All kinds (i.e., User (u), Group (g), and Other (o))

Each file and directory have three permissions for all three owner types:

Files | Mode | Abbrevation | Absolute Mode | Description | | --- | --- | --- | --- | | Read | r | 4 | Allow viewing or copying file contents. | | Write | w | 2 | Permits modifying file content. | | Execution | x | 1 | Enablesrunning executable files (scripts or programs). |

Directory

Mode	Abbrevation	Absolute Mode	Description
Read	r	4	List files and copies them from the directory.
Write	w	2	Adds or deletes files (requires execute permission).
Execution	x	1	Allows entering the directory.

File Permissions have two modes. An absoute mode and symbolic mode. The modes detail the type of enteries required for permissions to take effect.

Symbolic Mode
- Symbolic mode allows you to modify permissions based on their current state.
- +: Adds permissions.
- -: Removes permissions.
- =: Sets permissions explicitly.

Absolute Mode

In absolute mode, you explicitly specify the permissions using numeric value (octal notation). These values represent the combination of read, write, and execute permissions for the owner, group, and others.

Numeric Value	Mode	Description
0	*---*	No permissions
1	*--x*	Execute only
2	*-w-*	Write only
3	*-wx*	Write and execute
4	*r--*	Read only
5	*r-x*	Read and execute
6	*rw-*	Read and write
7	*rwx*	Read, write, and execute

File Types

Character	File Type	How to Create	Description
-	Regular file	Any program that writes a file	Common files like text, code, and binaries
b	Block special file	`mknod`	Storage devises like disks
c	Character scecial file	`mknod`	Devices that read/write character data (e.g., keyboard)
d	Directory	`mkdir`	A folder containing files and subdirectories
l	Symbolic link	`ln -s`	A reference to another file or directory
p	Named pipe	`mkfifo`	FIFO queue for inter-process communication
s	Socket	`nc -U`	Network communication between processes
D	Door	Created by some servers	Specific to Solaris/OpenIndiana systems

Permission Placement
1. Type
2. User
3. Group
4. Other
Permissions

bash

chmod ugo+rwx

bash

chmod 770 <file/directory-name>

chmod 770 =>

user: 7 = 4 + 2 + 1

group: 7 = 4 + 2 + 1

other: 0 = None

-> rwxrwx---

Ownership

Change onwnership (e.g., change onwnership of a directory to root )

bash

chown root <directory-name>

Change group (e.g., change group of a directory)

bash

chgrp <group-name> <directory-name>

Change ownership and group for a directory

bash

chown <ownership-name>:<group-name> <directory-name>

Spacial Permissions

Numeric Value	Mode	Description
4XXX	SUID (Set User ID)	Executes the file with the owner's privileges instead of the user's.
2XXX	SGID (Set Group ID)	Executes the file with the group's privileges or inhereits the directory's group.
1XXX	Stick Bit	Prevents users from deleting file they don't own in shared directories.

SUID (4XXX): Runs the file eith the owner's permissions (e.g., passwd).
Set:
bash
```
chmod u+s <file>
```
OR
bash
```
chmod 4755 <file>
```
Display: rwsr-xr-x
SGID (2XXX): Runs the file with the group's permission; new files in directories inherit the group.
Set:
bash
```
chmod g+s <dir>
```
OR
bash
```
shmod 2755 <dir>
```
Display (file/dir): rwxr-sr-x
Sticky Bit (1XXX): Restricts file delting in shared directories (/temp).
Set:
bash
```
chmod +t <dir>
```
OR
bash
```
chmod 1777 <dir>
```
Display: rwxrwxrwt
Examples

Permission	Command	Effect
*`-rwsr-xr-x`*	`chmod 4755 <file>`	Enables SUID
*`-rwxr-sr-x`*	`chmod 2755 <file>`	Enables SGID
*`drwsrwsr-x`*	`chmod 4775 <file>`	Enables SGID on a directory
*`drwxrwxrwt`*	`chmod 1777 <file>`	Enables Sricky Bit

Umask (User Mask)

umask defines the default permissions for newly created files and directories by subtractingits value from the maximum possible permissions.

Default Behavior:
Files: Maximum permission is 666 (rw-rw-rw-), but they never get execute (x) by default.
Directories: Maximum permission is 777 (rwxrwxrwx).
Example:

If umask is 022:

Files: 666 - 022 = 644 → rw-r--r--
Directories: 777 - 022 = 755 → rwxr-xr-x
Check & Set umask:
Check current umask:
bash
```
umask
```
Set umask (e.g., 027):
bash
```
umask 027
```
- Files → 640 ( rw-r----- )
- Directories → 750 ( rwxr-x--- )

To make changes persistent, add umask to ~/.bashrc or /etc/profile.

Partitioning

Show parthtion for GPT

bash

gdisk /dev/sda

Show partition for MBR

bash

fdisk /dev/sda

Show partition graphicaly

bash

cfdisk /dev/sda

Show partition graphicaly for GPT

bash

cgdisk /dev/sda

Mount & Unmount

Mount sdb1 on the /mnt

bash

mount /dev/sdb1 /mnt/

Show open process in /mnt

bash

lsof /mnt/

Unmaount /mnt

bash

umount /mnt

Network Management

IP Address

bash

ip a

bash

ip addr

Show opening ports

bash

nmap <host-name>

Time Management

show date

bash

date

Show and setting information of system time

bash

timedatectl

Change timezone

bash

timedatectl set-timezone Asia/Tehran

Process Management

Show jobs

bash

jobs

Run process in background

bash

<app-name> &

bash

<app-name>
^Z
bg

Show processes

bash

htop

top settings

With space key you can deactivate option

bash

top
f

Install Arch Linux

Install dependencies

zsh

pacman -Syyy

Install reflector package for find near mirror

zsh

pacman -S reflector

Hint: If get an error, use pacman-key --init

Find and update nearest mirror list

Flags	Argument	Description
`-c`	country name	Country name
`-a`	age	last update of mirror
`--sort`	rate	Sorting by rate
`--save`	file path	Save mirrors to use from its

zsh

reflector -c Iran -a 6 --sort rate --save /etc/pacman.d/mirrorlist

Partitioning

zsh

cfdisk /dev/sda

Select gpt
Create space 300M (300MiB)
Select type EFI System
New space for root with type Linux filesystem
New space for home with type Linux filesystem
New space for swap with type Linux swap
Write partitioning and yes and Quit
Check partitioning
zsh
```
lsblk
```
Making file system
Making boot drive
zsh
```
mkfs.fat -F /dev/sda1
```
Making root drive
zsh
```
mkfs.ext4 /dev/sda2
```
Making home drive
zsh
```
mkfs.ext4 /dev/sda3
```
Making swap drive
zsh
```
mkswap /dev/sda4
```
Mounting
Mounting swap
zsh
```
swapon /dev/sda4
```
Mounting /dev/sda2 in /mnt (root)
zsh
```
mount /dev/sda2 /mnt
```
- Making the directories for /home & /boot
zsh
```
mkdir /mnt/home /mnt/boot
```
Mounting /dev/sda1 in /mnt/boot (boot)
zsh
```
mount /dev/sda1 /mnt/boot
```
Mounting /dev/sda3 in /mnt/home (home)
zsh
```
mount /dev/sda3 /mnt/home
```
Install requirements software

ّInstall dependencies in /mnt path

zsh

pacstrap /mnt base linux linux-firmware vim tmux

Generate file system table
This command extracts the mounted partitions in /mnt using their UUIDsand writes the info to /mnt/etc/fstab, so the installed system can properly identify and mount them at boot--even if their device names change.

zsh

genfstab -U /mnt >> /mnt/etc/fstab

Switching to Arch Linux
The command switches into the installed system at /mnt, allowing you to configure it as if you had booted directly into it.
zsh
```
arch-chroot /mnt
```
Select timezone

zsh

ln -sf /usr/share/Zoneinfo/Asia/Tehran /etc/localtime
hwclock --systohc

Select system language
Select and set language
zsh
```
vim /etc/locale.gen
```
Uncommenting the en_US.UTF-8 UTF-8 and saving an exit
Generate language
zsh
```
locale-gen
```

Configuration

zsh

echo "LANG=en_US.UTF-8" >> /etc/locale.conf

Create hostname for system

zsh

echo "My-Hostname" > /etc/hostname

zsh

echo "127.0.0.1    localhost
::1        localhost
127.0.1.1    ArchLinux.localdomain ArchLinux" >> /etc/hosts

Create password for root

zsh

passwd

Update system and packages

zsh

pacman -Syyy
pacman -Syu

Install requires packages

zsh

pacman -S grub efibootmgr networkmanager network-manager-applet dialog wpa_supplicant mtools dosfstools base-devel linux-headers xdg-user-dirs xdg-utils nfs-utils bluez bluez-utils pipewire pipewire-alsa pipewire-pluse pipewire-jack bash-completion openssh reflector os-prober tmux vim htop

Install grub

zsh

grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=GRUB

zsh

grub-mkconfig -o /boot/grub/grub.cfg

Enables required packages

zsh

systemctl enable NetworkManager
systemctl enable bluetooth
systemctl enable reflector.timer

Adding user
Add user
zsh
```
useradd -m <username>
```
Add password for user
zsh
```
passwd <username>
```
Add user to wheel group
zsh
```
usermod -aG wheel <username>
```

Add user privilege specification

zsh

## ## User privilage specification ##

root ALL=(ALL:ALL) ALL <username> ALL=(ALL:ALL) ALL

Exit
zsh
```
exit
```
Umount and reboot system
zsh
```
umount -a
reboot
```
Install graphical environment

Install KDE

zsh

sudo timedatectl set-ntp true

zsh

sudo hwclock --systohc

zsh

sudo pacman -Syyy

zsh

sudo reflector -c Iran -a 6 --sort rate --save /etc/pacman.d/mirrorlist

zsh

sudo pacman -S xorg sddn plasma kde-applications firefox chromium

zsh

sudo reboot

zsh

sudo pacman -S xf86-video-vmware

zsh

sudo reboot

Install GNOME

zsh

sudo pacman -S gnome gnome-extra gnome-tweaks

zsh

sudo pacman -S archlinux-wallpaper

Emmet (HTML-CSS)

HTML

📑 Emmet CheatSheet
Command: a:www.google.com
Description: Add href to the <a> tag.
Result:
html
```
<a href="www.google.com"></a>
```
Command: a[https://google.com]
Description: Add href to the <a> tag.
Result:
html
```
<a href="https://google.com"></a>
```
Command: ul<li{example text $}*5
Description: Add content to multiple <li> tags and repeat them.

Result:

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:

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:

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

bash

head -n 15 file.txt

tail

View the last 15 lines of the file

bash

tail -n 15 file.txt

cat

Show files with line numbers

bash

cat -n file.txt

grep

Filter file after line 190 by "ali"

bash

grep -A 190 ali file.txt

bash

tail -n 40 file.txt | grep ali

Filter file before line 190 by "ali"
bash
```
grep -B ali file.txt
```
To don't show phrase(for example: filter by ali but does include hadi)
bash
```
grep ali | grep -v hadi
```
To recursive filter
bash
```
grep -r .py ~/Desktop
```
egrep

For RegEx

find exactly a and 2 l
bash
```
egrep 'al{2}' file.txt
```
find a and minimum 2 l
bash
```
egrep 'al{2,}' file.txt
```
find a and maximum 2 l
bash
```
egrep 'al{,2}' file.txt
```
diff
differente lines in 2 simailar files
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
bash
```
ls -lh | cut --delimiter=" " -f 5,10 > fileinfo.txt
```
tr

translate or delete characters

lowercase to uppercase (freq -> FREQ)
bash
```
echo 'freq' | tr [:lower:] [:upper:]
```

Phone

get username

bash

whoami

get IP

pkg install net-tools

bash

ifconfig

run ssh in phone

bash

sshd

set password

bash

passwd

AND

bash

chmode 600 ~/.ssh/authorized_keys

close ssh

bash

exit

Z-shell

git alias z-shell

grafical log

zsh

gloga

Bash

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

bash

sort < file.txt

| : pipe (stdin)

bash

cat file.txt | sort

(stdin)

bash

sort file.txt

0 : stdin
1 : stdout
2 : stderr
Bash completion
if bash completion is disable
bash
```
sudo vim /etc/inputrc
```
chane disable-completion on to disable-completion off or delete this line.
bash
```
set disable-completion off
```
variables
show variables
bash
```
env
```
show variables
bash
```
echo $PWD
```
define temporary variable
bash
```
export MYVAR=/home/path
```
define permanently variable

bash

vim ~/.bashrc

Adding variables permanently

bash

# export SYSTEMD_PAGER=
export MYVARFILE=/home/path

apply changes

bash

source ~/.bashrc

define alias

bash

vim ~/.bashrc

adding alias command

bash

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

bash history

show all commands

bash

vim ~/.bash_history

run commands from history (for example run command 6)

bash

!6

clear history

bash

history -c
history -w

bash logout

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

append stdout of ls -l command into new_log file

bash

vim ~/.bash_logout

bash

# ~/.bash_logout
ls -l >> new_log

bash profile

similar to bashrc

Bash Scripting

shebang

#!/bin/bash

bash scripting check writeable

bash

ls -l

if not writeable
bash
```
chmode +x bash_script.sh
```
run bash script

bash

./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

Multi line

: "
  line1
  line2
  line3
  ...
  end line
  "

Printf formatting

Specifier	Description
%%	Prints "%" symbol
%c	Takes arguments as a single character
%e & %E	Take argument in floating-point number and prints in exponential notation, %e for lower case letter and %E for capital letter
%g & %G	Take argument in floating-point number and prints in normal or exponential notation
%f	Takes argument as floting number
%d	Takes arguments as signed integers
%u	Takes arguments as unsigned integers
%o	Takes argument as an unsigned octal number
%x & %X	Takes arguments as unsigned hexadecimal integers

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

Arguments

Get Arguments

args=("$@")

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

All Arguments

echo $@

Number of Arguments

echo $#

Array

Make Array

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

Getting 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

bash

value

Use $? to get numeric returned vale

func_name() {
  echo "value"
  return 12
}

func_name
echo $?

output

bash

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

bash

app_name.sh ali
hello, ali

Database

Mongo DB

Install MongoDB
Start

bash

sudo systemctl start mongod

Enable

bash

sudo systemctl enable mongod

Run & Test

bash

mongosh

Exit

mongodb

exit

Show all database

mongodb

show dbs

Create or Connect Database

mongodb

use my_database

Create Collecation

mongodb

db.createCollection("collection_name")

Show Collections

mongodb

show collections

Current Database

mongodb

db

Remove Database

mongodb

db.dropDatabase()

Remove Collection

mongodb

db.collection_name.drop()

Add Data to collection

mongodb

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

Show all documents of a collection

mongodb

db.collection_name.find({})

mongodb

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

Show all documents in a collecation that contain condition

mongodb

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

Show one field in all document from collecation

mongodb

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

Show document with limited results

mongodb

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

Show documents and ignored numbers of first result

mongodb

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

Show documents with multi conditions

AND

mongodb

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

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
- $ne -> not equal
mongodb
```
db.collection_name.find({age: {$gt: 15}})
```
Update document

mongodb

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

Remove Objects contains similar values

mongodb

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

Remove spacial objects

mongodb

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

Jupyter Notebook

Write and create file by jupyter

ipynb

%%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

Periority	Operators	Associativity
1	()	Left to Right
2	**	Right to Left
3	+x and -x	Left to Right
4	*, /, //, and %	Left to Right
5	+ and -	Left to Right

Tips
- The output of division in Python is decimal number.
py
```
30 / 2

>>> 15.0
```
- Write large numbers in Python for convenience with underescores
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

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.

bat

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

bat

copy file.txt con

output

bat

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

bat

del file.txt