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https://github.com/sanhphanvan96/notes

Useful commands in Kali Linux, MacOs, Ubuntu, ...
https://github.com/sanhphanvan96/notes

ansible ansible-galaxy cheatsheet docker dockercompose ibus-unikey install kali-linux letsencrypt linux macos nginx python rails reverse-proxy ruby ssl vagrant yarn zsh

Last synced: about 1 month ago
JSON representation

Useful commands in Kali Linux, MacOs, Ubuntu, ...

Host: GitHub
URL: https://github.com/sanhphanvan96/notes
Owner: sanhphanvan96
Created: 2018-07-07T03:48:20.000Z (over 6 years ago)
Default Branch: master
Last Pushed: 2024-09-23T13:32:54.000Z (about 2 months ago)
Last Synced: 2024-09-28T21:04:58.550Z (about 1 month ago)
Topics: ansible, ansible-galaxy, cheatsheet, docker, dockercompose, ibus-unikey, install, kali-linux, letsencrypt, linux, macos, nginx, python, rails, reverse-proxy, ruby, ssl, vagrant, yarn, zsh
Homepage:
Size: 15.1 MB
Stars: 20
Watchers: 1
Forks: 11
Open Issues: 1
Metadata Files:
- Readme: README.md
- Security: security/general.md

Awesome Lists containing this project

README

- [Install for Kali](#install-for-kali)
- [Adding a new user in Kali Linux](#adding-a-new-user-in-kali-linux)
- [Oh My ZSH](#oh-my-zsh)
- [Install Docker](#install-docker)
- [Install Docker Compose](#install-docker-compose)
- [Install Visual Studio Code](#install-visual-studio-code)
- [Install Maven](#install-maven)
- [Install lastest Sublime](#install-lastest-sublime)
- [Add application to dash (launch icon)](#add-application-to-dash-launch-icon)
- [Install NodeJS](#install-nodejs)
- [Git on the Server - Generating Your SSH Public Key](#git-on-the-server---generating-your-ssh-public-key)
- [Install Atom](#install-atom)
- [Install ‘apt-fast’ to Speed Up apt-get/apt Package Downloads Using Multiple Mirrors](#install-apt-fast-to-speed-up-apt-getapt-package-downloads-using-multiple-mirrors)
- [Install Mongodb (docker)](#install-mongodb-docker)
- [Install Ibus Unikey](#install-ibus-unikey)
- [Install aria2: lightweight multi-protocol, multi-connection command-line, cross platform utility](#install-aria2-lightweight-multi-protocol-multi-connection-command-line-cross-platform-utility)
- [Errors](#errors)
- [1. Cannot use apt-get: Could not get lock /var/lib/dpkg/lock](#1-cannot-use-apt-get-could-not-get-lock-varlibdpkglock)
- [2. Get rid of Sudo](#2-get-rid-of-sudo)
- [3. MySQL: Access denied for user 'root'@'localhost'](#3-mysql-access-denied-for-user-rootlocalhost)
- [4. /var/log Disk Space Issues](#4-varlog-disk-space-issues)
- [5. Kali cannot connect to network](#5-kali-cannot-connect-to-network)
- [Some helpful commands](#some-helpful-commands)
- [1. Multiple firefox profile](#1-multiple-firefox-profile)
- [2. services](#2-services)
- [3. docker](#3-docker)
- [4. maven](#4-maven)
- [5. java](#5-java)
- [6. systemctl](#6-systemctl)
- [7. sqlmap](#7-sqlmap)
- [8. python](#8-python)
- [9. netstat](#9-netstat)
- [10. time](#10-time)
- [11. apt / apt-get](#11-apt--apt-get)
- [12. ngrok or serveo](#12-ngrok-or-serveo)
- [13. yarn and npm](#13-yarn-and-npm)
- [14. Rails simple cheat sheet](#14-rails-simple-cheat-sheet)
- [15. Git](#15-git)
- [16. mysql](#16-mysql)
- [17. stat: display file status](#17-stat-display-file-status)
- [18. openssl](#18-openssl)
- [9999. Some combine commands](#9999-some-combine-commands)
- [END](#end)

# Install for Kali

## [Adding a new user in Kali Linux](https://www.linkedin.com/pulse/20140502074357-79939846-adding-a-new-user-in-kali-linux)

```sh
useradd -m username

passwd username

usermod -a -G sudo username

chsh -s /bin/bash username
```

## [Oh My ZSH](https://github.com/robbyrussell/oh-my-zsh)

`sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"`

```sh
nano ~/.zshrc
```

and change

```
ZSH_THEME="gnzh"
```
- Change default shell to ZSH for current user: ```sudo chsh -s /bin/zsh $(whoami)```
## [Install Docker](https://www.kali.org/docs/containers/installing-docker-on-kali/)

## [Install Docker Compose](https://docs.docker.com/compose/install/)

```sh
sudo curl -L https://github.com/docker/compose/releases/download/1.21.2/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
```

## [Install Visual Studio Code](https://code.visualstudio.com/docs/setup/linux#_installation)

```sh
sudo dpkg -i .deb
sudo apt-get install -f # Install dependencies
```

## [Install Maven](http://www.baeldung.com/install-maven-on-windows-linux-mac)

## [Install lastest Sublime](http://docs.sublimetext.info/en/latest/getting_started/install.html)

```
cd ~
wget http://c758482.r82.cf2.rackcdn.com/sublime-text_build-3083_amd64.deb
```

- Key

```
----- BEGIN LICENSE -----
Member J2TeaM
Single User License
EA7E-1011316
D7DA350E 1B8B0760 972F8B60 F3E64036
B9B4E234 F356F38F 0AD1E3B7 0E9C5FAD
FA0A2ABE 25F65BD8 D51458E5 3923CE80
87428428 79079A01 AA69F319 A1AF29A4
A684C2DC 0B1583D4 19CBD290 217618CD
5653E0A0 BACE3948 BB2EE45E 422D2C87
DD9AF44B 99C49590 D2DBDEE1 75860FD2
8C8BB2AD B2ECE5A4 EFC08AF2 25A9B864
------ END LICENSE ------
```

## Add application to dash (launch icon)

```
sudo vim /usr/share/applications/intellij.desktop
```

- Add these lines

```
[Desktop Entry]
Version=13.0
Type=Application
Terminal=false
Icon[en_US]=/home/rob/.intellij-13/bin/idea.png
Name[en_US]=IntelliJ
Exec=/home/rob/.intellij-13/bin/idea.sh
Name=IntelliJ
Icon=/home/rob/.intellij-13/bin/idea.png
```

## [Install NodeJS](https://nodejs.org/en/download/package-manager/)

```
curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
sudo apt-get install -y nodejs
```

- To install the Yarn package manager, run:

```
curl -sL https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
sudo apt-get update && sudo apt-get install yarn
```

## [Git on the Server - Generating Your SSH Public Key](https://help.github.com/articles/connecting-to-github-with-ssh/)

- Check to see if you have a key already by going to that directory and listing the contents

```
$ cd ~/.ssh
$ ls
authorized_keys2 id_dsa known_hosts
config id_dsa.pub
```

- Generate SSH key

```sh
$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/sanhpv/.ssh/id_rsa):
Created directory '/home/sanhpv/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/sanhpv/.ssh/id_rsa.
Your public key has been saved in /home/sanhpv/.ssh/id_rsa.pub.
The key fingerprint is:
d0:82:24:8e:d7:f1:bb:9b:33:53:96:93:49:da:9b:e3 [email protected]
```

- The public keys look something like this

```
$ cat ~/.ssh/id_rsa.pub
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAklOUpkDHrfHY17SbrmTIpNLTGK9Tjom/BWDSU
GPl+nafzlHDTYW7hdI4yZ5ew18JH4JW9jbhUFrviQzM7xlELEVf4h9lFX5QVkbPppSwg0cda3
Pbv7kOdJ/MTyBlWXFCR+HAo3FXRitBqxiX1nKhXpHAZsMciLq8V6RjsNAQwdsdMFvSlVK/7XA
t3FaoJoAsncM1Q9x5+3V0Ww68/eIFmb1zuUFljQJKprrX88XypNDvjYNby6vw/Pb0rwert/En
mZ+AW4OZPnTPI89ZPmVMLuayrD2cE86Z/il8b+gw3r3+1nKatmIkjn2so1d01QraTlMqVSsbx
NrRFi9wrf+M7Q== [email protected]
```

- [Add this key to Github account](https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/)

## Install Atom

```sh
curl -sL https://packagecloud.io/AtomEditor/atom/gpgkey | sudo apt-key add -
sudo sh -c 'echo "deb [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main" > /etc/apt/sources.list.d/atom.list'
sudo apt-get update
sudo apt-get install atom
```

## [Install ‘apt-fast’ to Speed Up apt-get/apt Package Downloads Using Multiple Mirrors](https://github.com/ilikenwf/apt-fast)

- Firstly add the the PPA for apt-fast package as follows and then update your system.

```
sudo add-apt-repository ppa:apt-fast/stable
sudo apt-get update
```

- Then

```
sudo apt-get -y install apt-fast
```

or the second method:

```
git clone https://github.com/ilikenwf/apt-fast.git
cd apt-fast
sudo ./quick-install.sh
```

## Install Mongodb (docker)

- Dockerfile

```dockerfile
FROM mongo
VOLUME /data/db
```

- build mongo image: `docker build -t mongodb-expose-27017 .`

- docker-compose.yml

```yml
version: "3"
services:
mongodb:
container_name: mongodb-expose-27017
image: mongo
ports:
- 27017:27017
volumes:
- ./db:/data/db
```

- [install MongoDB Compass](https://docs.mongodb.com/compass/master/install/):

```sh
wget https://downloads.mongodb.com/compass/mongodb-compass_1.12.5_amd64.deb;
sudo dpkg -i mongodb-compass_1.12.5_amd64.deb;
DEBUG=* mongodb-compass;
```

- Test connect by NodeJs:

```js
const MongoClient = require("mongodb").MongoClient;

MongoClient.connect("mongodb://0.0.0.0:27017", (err, database) => {
if (err) return console.log(err);
db = database.db("db_name");
collection = db.collection("collection_name");
});
```

## Install Ibus Unikey

```sh
sudo apt-get install ibus-unikey
```

- Logout and login again to make new plugin works.

- Go to `Settings` -> `Region & Language`, add `Vietnamese(Unikey)`.

- To switch input type press `Supper` + `Space`

## Install aria2: lightweight multi-protocol, multi-connection command-line, cross platform utility

- Features: [https://github.com/aria2/aria2#features](https://github.com/aria2/aria2#features)
- Options: [https://aria2.github.io/manual/en/html/aria2c.html#options](https://aria2.github.io/manual/en/html/aria2c.html#options)
- Sample command: `aria2c -x 16 -s 16 --file-allocation=none -d ./`

# Errors

## 1. Cannot use apt-get: Could not get lock /var/lib/dpkg/lock

```
E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable)

E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?
```

- Method 1: There could be many reasons why you see this error. The first and most obvious reason is that some other process is using APT package management tool (the apt or apt-get command, in other words). Check if Ubuntu Software Center or Synaptic Package Manager is running or not.
```sh
ps aux | grep -i apt
sudo kill -9
#or
sudo killall apt apt-get
```
- Method 2: The first method would fix the problem for you in most cases. But my case was a bit different. I was updating my system and accidentally closed the terminal. For that reason, there were no processes running apt, but it still showed me the error.
- In this case, the root cause is the lock file. Lock files are used to prevent two or more processes from using the same data. When apt or apt-commands are run, they create lock files in a few places. If the previous apt command was not terminated properly, the lock files are not deleted and hence they prevent any new instances of apt/apt-get commands.

```
lsof /var/lib/dpkg/lock
lsof /var/lib/apt/lists/lock
lsof /var/cache/apt/archives/lock
```
- It’s possible that the commands don’t return anything, or return just one number. If they do return at least one number, use the number(s) and kill the processes like this (replace the PID with the numbers you got from the above commands):
```
sudo kill -9 PID
```

- Use the lsof command to get the process ID of the process holding the lock files. Run these commands one by one.

```sh
sudo rm /var/lib/apt/lists/lock

sudo rm /var/cache/apt/archives/lock

sudo rm /var/lib/dpkg/lock
```
- After that, reconfigure the packages:
```
sudo dpkg --configure -a
```

## 2. [Get rid of Sudo](https://unix.stackexchange.com/a/26077)

- docker

```sh
sudo usermod -aG docker $USER # recommended, specially for docker
```

```sh
sudo chown sanhpv /var/run/docker.sock # shouldn't do this
```

## 3. MySQL: Access denied for user 'root'@'localhost'

```
sudo service mysql stop

sudo mysqld_safe --skip-grant-tables &

mysql -u root
```

```mysql
mysql> use mysql;
Database changed
mysql> select * from user;
Empty set (0.00 sec)
mysql> truncate table user;
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to root@localhost identified by 'YourNewPassword' with grant option;
Query OK, 0 rows affected (0.01 sec)
mysql> select host, user from user;
+-----------+------+
| host | user |
+-----------+------+
| localhost | root |
+-----------+------+
1 row in set (0.00 sec)
mysql> quit;
```

```sh
[root ~]# kill -KILL [PID of mysqld_safe]
[root ~]# kill -KILL [PID of mysqld]
[root ~]# service mysql start
```

## 4. /var/log Disk Space Issues

- Recently, I started noticing that my computer keeps running out of space for no reason at all. I
mean I didn't download any large files and my root drive should not be having any space
issues, and yet my computer kept tellling me that I had '0' bytes available or free on my /root/
drive. As I found it hard to believe, I invoked the 'df' command (for disk space usage):

```
sanhpv@kali: df

Filesystem 1K-blocks Used Available Use% Mounted on
udev 1951988 0 1951988 0% /dev
tmpfs 394016 41468 352548 11% /run
/dev/sda3 62799588 39764444 815384 97% /
tmpfs 1970072 281384 1688688 15% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 1970072 0 1970072 0% /sys/fs/cgroup
/dev/sda1 98304 29425 68879 30% /boot/efi
tmpfs 394012 12 394000 1% /run/user/130
tmpfs 394012 52 393960 1% /run/user/1000

sanhpv@kali: find / -size +2000M

/var/log/kern.log
/var/log/messages.1
/var/log/messages
/var/log/syslog
/var/log/kern.log.1
```

- Clearly, the folder '/var/log' needs my attention. Seems like some kernel log files are
humongous in size and have not been 'rotated' (explained later). So, I listed the contents of
this directory arranged in order of decreasing size:

```
sanhpv@kali: cd /var/log
sanhpv@kali: ls -s -S

total 34891876
15180996 kern.log.1 107372 syslog.6.gz 40 auth.log 4 exim4 4 stunnel4
4658020 messages.1 93308 syslog.5.gz 40 user.log 4 gdm3 4 sysstat
4241176 syslog 58468 messages.2.gz 36 daemon.log.2.gz 4 glusterfs 4 unattended-upgrades
4222736 kern.log 25388 debug.2.gz 4 faillog 4 inetsim 4 alternatives.log
1921736 debug.1 5356 user.log.1 32 wtmp 4 installer 4 macchanger.log.1.gz
1762268 syslog.1 896 daemon.log.1 16 daemon.log 4 mysql 4 macchanger.log.2.gz
1285180 messages 4 lastlog 8 auth.log.2.gz 4 nginx 0 bootstrap.log
517736 debug 236 auth.log.1 4 apache2 4 ntpstats 0 btmp
323240 syslog.4.gz 140 user.log.2.gz 4 apt 4 openvpn 0 fontconfig.log
200320 kern.log.2.gz 84 dpkg.log 4 chkrootkit 4 postgresql
162340 syslog.2.gz 4 tallylog 4 couchdb 4 samba
124556 syslog.3.gz 48 Xorg.1.log 4 dradis 4 speech-dispatcher

sanhpv@kali: sudo /etc/cron.daily/logrotate
```

- It ran for a while as it rotated the logs. logrotate is meant to automate the task of
administrating log files on systems that generate a heavy amount of logs. It is responsible for
compressing, rotating, and delivering log files. Read more about it [here](https://linux.die.net/man/8/logrotate).

- What I hoped by running logrotate was that it would rotate and compress the old log files so I
can quickly remove those from my system. Why didn't I just delete that '/var/log' directory
directly? Because that would break things. '/var/log' is needed by the system and the system
expects to see it. Deleting it is a bad idea. So, I needed to ensure that I don't delete anything
of significance.
After a while, logrotate completed execution and I was able to see some '.gz' compresses files
in this directory. I quickly removed (or deleted) these.

- Since these had already been rotated, I figured it would be safe to remove these as well. But instead of doing
an 'rm' to remove them, I decided to just empty them (in case they were being used
somewhere)

```
sanhpv@kali: sudo su
sanhpv@kali: >kern.log.1
sanhpv@kali: >messages.1
sanhpv@kali: >syslog
sanhpv@kali: >kern.log
```

## 5. Kali cannot connect to network

- Restart Network service:
```
sudo /etc/init.d/networking restart
```
- Cannot connect to some host -> maybe wrong datetime: need to update your datetime
```
apt-get install -y ntpdate
ntpdate -v pool.ntp.org
```

# Some helpful commands

## 1. Multiple firefox profile

```
./firefox -ProfileManager
```

## 2. services

```
sudo service --status-all | grep +
sudo service mysql start
sudo service mysql stop
```

## 3. docker

```sh
docker exec -it f525926e0172 bash
docker inspect ce84c1397ff0 --format '{{ .Config.Env | json }}' | python -m json.tool
docker images
docker ps
docker rmi name_of_image
docker rm $(docker ps -aq)
docker logs -tf name_of_container
docker-compose pull
docker-compose up
docker-compose up --force-recreate
docker-compose up name_of_service #start a particular service defined in docker-compose file
docker-compose down
docker-compose -f docker-compose.debug.yml up --build
docker stop $(docker ps -q) #stop all containers, forcefully: -f
docker rm $(docker ps -a -q) #remove all containers, forcefully: -f
docker rmi $(docker images -q) #remove all docker images, forcefully: -f
docker volume ls -qf dangling=true | xargs -r docker volume rm #remove all docker volumes
docker rm (docker ps -a |grep redis |awk '{print $1}') #Remove all containers by image.ex: remove all redis containers
docker network create nginx-proxy
# magic with docker buildkit
DOCKER_BUILDKIT=1 docker build -t imagename -f multiplestages.Dockerfile .
```

- Dockerfile

```dockerfile
FROM maven:3.5-jdk-8

# Build source -> java application
COPY ./app /app
WORKDIR /app
RUN mvn -Dmaven.test.skip=true install

# Install some python packages(Todo: need build another image that has these package first)
WORKDIR /tmp
RUN curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
RUN python get-pip.py
RUN apt update -y
RUN apt install python-dev libpq-dev -y
RUN apt-get install python-mysqldb -y

# Python script for run later
COPY ./wait-for-mysql.py /tmp/wait-for-mysql.py
```

```python
import MySQLdb
import time
def try_to_connect():
print("Trying to connect aws-mysql.")
try:
connection = MySQLdb.connect(
host = 'aws-mysql',
user = 'sanhpv',
passwd = 'NYBpHxUmbGC9u3PMdPCR') #NUT YELP BESTBUY park HULU xbox USA music bestbuy GOLF COFFEE 9 usa 3 PARK MUSIC drip PARK COFFEE ROPE
cursor = connection.cursor()
cursor.execute("USE aws-db")
except Exception, e:
print str(e)
time.sleep(5)
try_to_connect()

try_to_connect()
```

- [Using multi-stage builds](https://docs.docker.com/develop/develop-images/multistage-build/) feature in Dockerfiles enables you to create smaller container images with better caching and smaller security footprint. When a docker image is built, each step is actually a container that is launched and saved, these are intermediate images. When you rebuild an image, docker will check if the files you use for its build have changed. If so, it will start again from the step that has been modified. To take advantage of the cache, we will pre-register the dependencies.

```Dockerfile
FROM maven:3.5.3-jdk-8 as maven
RUN mkdir --parents /usr/src/app
WORKDIR /usr/src/app

ADD pom.xml /usr/src/app/
RUN mvn verify clean --fail-never

ADD . /usr/src/app
RUN mvn install

FROM java:8
COPY --from=maven /usr/src/app/target/XVulB-*.war /opt/app.war
CMD ["java","-jar","-Dspring.profiles.active=docker","/opt/app.war"]
```

- docker-compose.yml

```yml
command: bash -c "python /tmp/wait-for-mysql.py && echo 'aws-mysql works fine' && java -jar -Dspring.profiles.active=docker ./target/app.jar"
```

- [Control startup order in Docker Compose](https://github.com/vishnubob/wait-for-it)

```
wait-for-it.sh host:port [-s] [-t timeout] [-- command args]
-h HOST | --host=HOST Host or IP under test
-p PORT | --port=PORT TCP port under test
Alternatively, you specify the host and port as host:port
-s | --strict Only execute subcommand if the test succeeds
-q | --quiet Don't output any status messages
-t TIMEOUT | --timeout=TIMEOUT
Timeout in seconds, zero for no timeout
-- COMMAND ARGS Execute command with args after the test finishes
```

```
./wait-for-it.sh www.google.com:80 -- echo "google is up"
wait-for-it.sh: waiting 15 seconds for www.google.com:80
wait-for-it.sh: www.google.com:80 is available after 0 seconds
google is up
```

- Pushing the docker image to docker hub repository:

```
docker login
docker build -t sanhphanvan/awesome .
docker push sanhphanvan/awesome
```

## 4. maven

```
mvn spring-boot:run
mvn clean package
mvn clean install
mvn verify
mvn -Dmaven.test.skip=true install
mvn -Dmaven.test.skip=true -Dspring.profiles.active=docker install
```

`validate` - validate the project is correct and all necessary information is available

`compile` - compile the source code of the project

`test` - test the compiled source code using a suitable unit testing framework. These tests should not require the code be packaged or deployed

`package` - take the compiled code and package it in its distributable format, such as a JAR.

`verify` - run any checks on results of integration tests to ensure quality criteria are met

`install` - install the package into the local repository, for use as a dependency in other projects locally

`deploy` - done in the build environment, copies the final package to the remote repository for sharing with other developers and projects

## 5. java

```
update-java-alternatives --set java-1.8.0-openjdk-amd64
```

## 6. systemctl

```sh
systemctl disable docker # disable boot service
systemctl --user start pulseaudio
systemctl --user status pulseaudio
systemctl --type=service
systemctl --type=service --state=active
systemctl --type=service --state=running
```

## 7. sqlmap

```
sqlmap -r ~/BurpRequest/minglex -p id --dbms=MySql --dbs --proxy=http://127.0.0.1:8080 --flush-session
```

## 8. python

- The SimpleHTTPServer module that comes with Python is a simple HTTP server that
provides standard GET and HEAD request handlers

```
python -m SimpleHTTPServer 9696
```

- or Ruby (recommended): Run [WEBrick](https://apidock.com/ruby/WEBrick) HTTP server

```
ruby -run -ehttpd . -9696
```

---

- Rather than step through code with a debugger, you can add the code module to your Python program to instruct the program to stop execution and enter into the interactive mode in order to examine how your code is working. The code module is part of the Python standard library.

- This is useful because you are able to leverage an interpreter without sacrificing the complexity and permanence that programming files can provide. Through using the code module you can avoid using print() statements throughout your code as a form of debugging, which can become unwieldy over time.

- To make use of the module as a method for debugging, you can use the interact() function of the module, which stops execution of the program at the point at which it is called, and provides you with an interactive console so that you can examine the current state of your program.

```python
import code
```

- insert this line to wherever you wanna create an object instance of the InteractiveConsole class, which emulates the behavior of the interactive Python interpreter

```python
code.interact(local=dict(globals(), **locals()))
```

- Enable colored terminal output for Python’s logging module [coloredlogs](https://pypi.org/project/coloredlogs/)

```python
import coloredlogs, logging
coloredlogs.install() #coloredlogs.install(level='DEBUG')
```

- with Ruby/Rails

```
gem install pry
```

```ruby
require 'pry'

puts 'requiring pry'
binding.pry
```

```ruby
From: /home/richard/Documents/eCommerceExample/spec/controllers/categories_controller_spec.rb @ line 21 :

16: end
17:
18: include_examples 'sets the proper global variables'
19:
20: it "returns http success" do
=> 21: binding.pry
22: expect(response).to have_http_status(:success)
23: end
24:
25: it 'returns a list of categories' do
26: expect(assigns(:categories).size).to eq(1)

[1] pry(#)>
```

- Pyenv: Install Multiple Python Versions for Specific Project
- Pyenv is a simple, powerful and cross-platform tool for managing multiple Python versions on Linux systems, that used for.
- Switching the global Python version on a per-user basis.
- Setting the local Python version on per-project basis.
- Managing of virtual environments created by anaconda or virtualenv.
- Overriding the Python version with an environment variable.
- Searching commands from multiple versions of Python and more.
- Github repo: [https://github.com/pyenv/pyenv](https://github.com/pyenv/pyenv)
- Tutorial [https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/](https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/)
- For Ruby: rbenv [https://github.com/rbenv/rbenv](https://github.com/rbenv/rbenv)

## 9. netstat

## 10. time

```
time ls -R
```

## 11. apt / apt-get

- ran a dpkg command to install a couple of .deb packages (ex: `sudo dpkg -i google-chrome-stable_current_amd64.deb`), but the install failed because some dependencies were missing.

```sh
apt-get -f install #-f, --fix-broken
```

- Most used commands:

```
update - Retrieve new lists of packages
upgrade - Perform an upgrade
install - Install new packages (pkg is libc6 not libc6.deb)
remove - Remove packages
purge - Remove packages and config files
autoremove - Remove automatically all unused packages
dist-upgrade - Distribution upgrade, see apt-get(8)
dselect-upgrade - Follow dselect selections
build-dep - Configure build-dependencies for source packages
clean - Erase downloaded archive files
autoclean - Erase old downloaded archive files
check - Verify that there are no broken dependencies
source - Download source archives
download - Download the binary package into the current directory
changelog - Download and display the changelog for the given package
```

## 12. ngrok or serveo

- To start a HTTP tunnel on port 80, run this next:

```
./ngrok http 80
```

- Expose local servers to the internet. No installation, no signup with serveo [https://serveo.net/](https://serveo.net/)

```
ssh -R 80:localhost:3000 serveo.net
```

```
ssh -R sudomain:80:localhost:3000 serveo.net
```

## 13. yarn and npm

```sh
npm install === yarn #Install is the default behavior.
npm install taco --save === yarn add taco #The Taco package is saved to your package.jsonimmediately.
npm uninstall taco --save === yarn remove taco #--savecan be defaulted in NPM by npm config set save true but this is non-obvious to most developers. Adding and removing from package.json is default in Yarn.
npm install taco --save-dev === yarn add taco --dev
npm update --save === yarn upgrade
npm install taco@latest --save === yarn add taco
npm install taco --global === yarn global add taco

npm init === yarn init
npm link === yarn link
npm outdated === yarn outdated
npm publish === yarn publish
npm run === yarn run
npm cache clean === yarn cache clean
npm login === yarn login
npm test === yarn test
npm install --production === yarn --production

```

- [Things yarn has that NPM doesn’t](https://infinite.red/files/yarn.pdf)

`yarn licenses ls` — Allows you to inspect the licenses of your dependencies

`yarn licenses generate-disclaimer` — Automatically create your license dependency disclaimer

`yarn why taco` — Identify why ‘taco’ package is installed, detailing which other packages depend upon it (thanks Olivier Combe).

`yarn upgrade-interactive` — Allows you to selectively upgrade specific packages in a simple way

## 14. [Rails simple cheat sheet](https://gist.github.com/mdang/95b4f54cadf12e7e0415)

## 15. Git

- Squash and Merge: Takes all the commits from the `bugfix` branch and merges it with your current branch (ex: `master`).

```
git checkout master
git merge --squash bugfix
git commit
```

- git aliases:

```
git config --global alias.co checkout
git config --global alias.br branch
```

- [Clone a subdirectory only of a Git repository?](https://stackoverflow.com/a/13738951/7596401) => keywords: `sparse clone/sparse checkout`

```bash
mkdir
cd
git init
git remote add -f origin
```

- This creates an empty repository with your remote, and fetches all objects but doesn't check them out. Then do:

```bash
git config core.sparseCheckout true
```

- Define which files/folders you want to actually check out. This is done by listing them in .git/info/sparse-checkout, eg:

```bash
echo "some/dir/" >> .git/info/sparse-checkout
echo "another/sub/tree" >> .git/info/sparse-checkout
```

- Update your empty repo with the state from the remote

```bash
git pull origin master
or
git pull --depth=1 origin master # shallow clone cuts off the history and the sparse checkout only pulls the files matching your patterns
```

- Bonus: as a function

```bash
function git_sparse_clone() (
rurl="$1" localdir="$2" && shift 2

mkdir -p "$localdir"
cd "$localdir"

git init
git remote add -f origin "$rurl"

git config core.sparseCheckout true

# Loops over remaining args
for i; do
echo "$i" >> .git/info/sparse-checkout
done

git pull origin master
)
```

- Usage:
```bash
git_sparse_clone "http://github.com/tj/n" "./local/location" "/bin"
```

## 16. mysql

- [Create new user and grant permissions](https://www.digitalocean.com/community/tutorials/how-to-create-a-new-user-and-grant-permissions-in-mysql):

```SQL
CREATE USER 'dev'@'localhost' IDENTIFIED BY 'password';
GRANT INSERT,SELECT ON db.table TO 'dev'@'localhost';
FLUSH PRIVILEGES;
```

```SQL
SHOW GRANTS;
SHOW GRANTS FOR 'dev'@'localhost';
SHOW GRANTS FOR CURRENT_USER();
```

## 17. stat: display file status

- The stat utility displays information about the file pointed to by file.
- Read, write or execute permissions of the named file are not required, but all directories listed in the path name leading to the file must be searchable. If no argument is given, stat displays information about the file descriptor for standard input. (quoted in `man stat`)
```bash
stat ./
stat *.*
```

## 18. openssl

```bash
openssl passwd -1 plain_password # => md5
openssl prime 123456781
openssl s_client -connect google.com.vn:443
```

## 9999. Some combine commands

```bash
history | grep docker | awk '{print $1="", $0 }' | sort | uniq
```

```bash
ls -la | awk -v OFS=' ' '{print $5, $1}'
ls -la | awk -v OFS='\t' '{print $5, $1}'
```

```
netstat -nv | grep -E "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" | awk '{print $9}' | head -n 1
```

```bash
for i in `vagrant global-status | grep virtualbox | awk '{ print $1 }'` ; do echo $i ; done
```

```bash
echo -e "\e[1;40m" ; clear ; while :; do echo $LINES $COLUMNS $(( $RANDOM % $COLUMNS)) $(( $RANDOM % 72 )) ;sleep 0.05; done|awk '{ letters="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789@#$%^&*()"; c=$4; letter=substr(letters,c,1);a[$3]=0;for (x in a) {o=a[x];a[x]=a[x]+1; printf "\033[%s;%sH\033[2;32m%s",o,x,letter; printf "\033[%s;%sH\033[1;37m%s\033[0;0H",a[x],x,letter;if (a[x] >= $1) { a[x]=0; } }}'
```

```bash
ps -o pid,user,%mem,command ax | sort -b -k3 -r | grep -z sanhpv
```
# END

`code = developer + coffee;`