python cheat sheet

python cheat sheet

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It's the Language of AI Security: Open any modern security platform leveraging AI, and you'll find Python at its core. Learning Python means understanding how your most advanced security tools actually work—and how to maximize their potential.
It Enables Rapid Response: When a new threat emerges, Python lets your team move quickly. Instead of waiting for vendor updates, you can adapt and create custom detection rules or automation workflows within hours.
It Amplifies Your Team's Capabilities: Security teams everywhere face resource constraints. Python automation helps your existing analysts handle more alerts, investigate more thoroughly, and respond more effectively—without burning out.
It Unifies Your Security Ecosystem: Most organizations have dozens of security tools that don't communicate well. Python serves as the universal connector, allowing you to build the integrations vendors don't provide and extract more value from your existing tools.
It Puts Your Team in Control: When pre-built solutions fall short—which they inevitably do—Python skills give your team the power to build exactly what you need for your unique environment and threat landscape.
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To create a Python virtual environment on Ubuntu 24.04 and ensure you can use pip3 and python3 commands inside it, follow these steps:
🐍 1. Install Python and Virtual Environment Tools

Open a terminal and run:

sudo apt update
sudo apt install -y python3 python3-venv python3-pip

🛠️ 2. Create a Virtual Environment

Choose a directory where you want to create the virtual environment, then run:

python3 -m venv venv

    This creates a folder named venv containing the virtual environment.

🚀 3. Activate the Virtual Environment

source venv/bin/activate

    Once activated, your prompt should change to something like:

    (venv) user@hostname:~$

✅ 4. Use pip3 and python3 Inside the Virtual Environment

When the virtual environment is activated:

pip3 install --upgrade pip   # Upgrade pip
pip3 install somepackage     # Example: Install a package
python3 --version            # Check Python version
pip3 --version               # Check pip version

🛑 5. Deactivate the Virtual Environment

To exit the virtual environment:

deactivate

🎯 To Reuse the Virtual Environment Later

Just navigate to the directory and activate it:

cd /path/to/venv
source venv/bin/activate
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pip-compile --output-file requirements.txt requirements.in
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python -V
python3 -V

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Method 1:from source
apt-get install zlib1g-dev
wget https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tgz
tar -xvf Python-3.6.3.tgz
cd Python-3.6.3
./configure
make 
make install
python3.6 -V

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Method 2: Install Python 3.6 from PPA
apt-get install software-properties-common python-software-properties
add-apt-repository ppa:jonathonf/python-3.6
apt-get update
apt-get install python3.6
python3.6 -V


$ python3 -V
Python 3.6.5
$ python -V
Python 2.7.15rc1

#change version
$ which python3
/usr/bin/python3
vi .bashrc
alias python='/usr/bin/python3'
$ python --version
Python 3.6.5
============================================================================
# install pip and Python 2.7
sudo apt-get install -y python-pip
pip --version

# install pip and Python 3
sudo apt install python3-venv python3-pip
pip3 --version

# install “SomePackage” into an environment with site.USER_BASE customized to ‘/myappenv’, do the following:
# pip will not perform a --user install in a --no-site-packages virtualenv (i.e. the default kind of virtualenv), 
# due to the user site not being on the python path. The installation would be pointless
export PYTHONUSERBASE=/myappenv
pip install --user SomePackage

# From within a --no-site-packages virtualenv (i.e. the default kind):
pip install --user requests
Can not perform a '--user' install. User site-packages are not visible in this virtualenv.
# From within a --system-site-packages virtualenv where SomePackage==0.3 is already installed in the virtualenv:
pip install --user SomePackage==0.4
Will not install to the user site because it will lack sys.path precedence
# From within a real python, where SomePackage is not installed globally:
pip install --user SomePackage
# From within a real python, where SomePackage is installed globally, but is not the latest version
pip install --user SomePackage
pip install --user --upgrade SomePackage

# From within a real python, where SomePackage is installed globally, and is the latest version
pip install --user SomePackage
pip install --user --upgrade SomePackage
pip install --user --ignore-installed SomePackage
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Prerequisites
python -V
python3 -V

# Install Virtualenv
sudo apt-get install python-virtualenv # method1
sudo easy_install virtualenv # method2
sudo pip install virtualenv # method3
conda install virtualenv # method4
virtualenv --version

# create and activate the virtual environment
mkdir ~/virtualenvironment
# create a folder for your new app
virtualenv ~/virtualenvironment/my_new_app
# add --no-site-packages if you want to isolate your environment from the main site packages directory
virtualenv --no-site-packages ~/virtualenvironment/my_new_app
cd ~/virtualenvironment/my_new_app/bin
# activate your environment
source activate
# exit your virtualenv
deactivate
# install an app in your Virtualenv
pip install flask

# Deleting your virtual environment
rm -rf ~/virtualenvironment
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# installing Django globally on the system.NOT DESIGNED FOR
sudo pip install django
# installing Django locally
pip install django
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# Install Virtualenv
sudo apt-get install python-virtualenv # method1
sudo pip install virtualenv # method3
conda install virtualenv # method4
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# activate your environment
source activate
# In the /bin directory there is an activate BASH script. 
./activate

# activate the environment
env/bin/pip
env/bin/python
source env/bin/activate

$ which python # globally 
/usr/bin/python
$ source env1/bin/activate
$ which python # locally on env1 virtual environment
/home/vagrant/myproject/env1/bin/python

 # use the versions of python and pip inside the environment
 env/bin/python
 env/bin/pip 
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# Build wheels for a requirement (and all its dependencies), and then install
$ pip wheel --wheel-dir=/tmp/wheelhouse SomePackage
$ pip install --no-index --find-links=/tmp/wheelhouse SomePackage
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# Compute the hash of a downloaded archive
pip download SomePackage
pip hash ./pip_downloads/SomePackage-2.2.tar.gz
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# Each project you work on has its own requirements.txt file
# you can use this to install the dependencies for that project into its virtual environment
env/bin/pip install -r requirements.txt


pip freeze > requirements.txt
pip install -r requirements.txt
pip install -r example-requirements.txt

# Generate a requirements file and then install from it in another environment.
$ env1/bin/pip freeze > requirements.txt
$ env2/bin/pip install -r requirements.txt

# if pkg1 requires pkg3>=1.0 and pkg2 requires pkg3>=1.0,<=2.0, and if pkg1 is resolved first, pip will only use pkg3>=1.0, 
# and could easily end up installing a version of pkg3 that conflicts with the needs of pkg2
requirements.txt
pkg1
pkg2
pkg3>=1.0,<=2.0

# ProjectA in your requirements file requires ProjectB but the latest version (v1.3) has a bug
# you can force pip to accept earlier versions
requirements.txt
ProjectA
ProjectB<1.3
# suppose a dependency, SomeDependency from PyPI has a bug, and you can’t wait for an upstream fix.
# You could clone/copy the src, make the fix, and place it in VCS with the tag sometag
requirements.txt
git+https://myvcs.com/some_dependency@sometag#egg=SomeDependency

pip install -c constraints.txt

$ pip install SomePackage            # latest version
$ pip install SomePackage==1.0.4     # specific version
$ pip install 'SomePackage>=1.0.4'     # minimum version
docopt == 0.6.1             # Version Matching. Must be version 0.6.1
keyring >= 4.1.1            # Minimum version 4.1.1
coverage != 3.5             # Version Exclusion. Anything except version 3.5
Mopidy-Dirble ~= 1.1        # Compatible release. Same as >= 1.1, == 1.*

# Upgrade an already installed SomePackage to the latest from PyPI.
pip install --upgrade SomePackage
# Install a particular source archive file.
$ pip install ./downloads/SomePackage-1.0.4.tar.gz
$ pip install http://my.package.repo/SomePackage-1.0.4.zip
# Install from a different index, and not PyPI
pip install --index-url http://my.package.repo/simple/ SomePackage
# Install from a local flat directory containing archives (and don’t scan indexes)
$ pip install --no-index --find-links=file:///local/dir/ SomePackage
$ pip install --no-index --find-links=/local/dir/ SomePackage
$ pip install --no-index --find-links=relative/dir/ SomePackage
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# install from local packages only, with no traffic to PyPI.
# download the archives that fulfill your requirements:
pip download --destination-directory DIR -r requirements.txt
# pip download --destination-directory DIR -r requirements.txt
# if some of your requirements don’t come as wheels from PyPI, and you want wheels
pip wheel --wheel-dir DIR -r requirements.txt
# to install from local only
pip install --no-index --find-links=DIR -r requirements.txt
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virtualenv env
env/bin/pip install requests
env/bin/pip install flask
env/bin/pip freeze> requirements.txt
virtualenv env1
env1/bin/pip install -r requirements.txt
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virtualenv --python=/usr/bin/python3.2 name_of_your_virtualenv
source activate name_of_your_virtualenv
python --version

virtualenv venv3 --python=`which python3`
virtualenv venv2 --python=`which python2`
venv3/bin/python --version
venv2/bin/python --version

virtualenv venv2 -p `which python2`
venv2/bin/python --version
Python 2.7.12
virtualenv venv3 -p `which python3`
venv3/bin/python --version
Python 3.5.2

virtualenv -p $(which python2) venvp2
venv2/bin/python --version
Python 2.7.12
virtualenv -p $(which python3) venvp3
venvp3/bin/python --version
Python 3.5.2

# call virtualenv with python version
python3 -m virtualenv -p $(which python3) venv3
venv3/bin/python --version
Python 3.5.2
python -m virtualenv -p $(which python2) venv2
venv2/bin/python --version
Python 2.7.12
python3 -m virtualenv -p $(which python2) venv1
venv1/bin/python --version
Python 2.7.12
python -m virtualenv -p $(which python3) venv5
venv5/bin/python --version
Python 3.5.2

# The venv module provides support for creating lightweight “virtual environments” with their own site directories
python3 -m venv virtualenv1
virtualenv1/bin/python --version
Python 3.5.2
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virtualenvwrapper
# make sure virtualenv is already installed
# the virtualenvwrapper tool is just some wrapper scripts around the main virtualenv tool.

# Install pip
sudo apt install python-pip

# Install Virtualenv
sudo pip install virtualenv # method3
virtualenv --version

# Install virtualenvwrapper
pip install virtualenvwrapper

which virtualenvwrapper.sh
/home/vagrant/.local/bin/virtualenvwrapper.sh

# Bash shell, either the ~/.bashrc file or the ~/.profile
cat >> ~/.bashrc << EOF
> export WORKON_HOME=$HOME/.virtualenvs   # Optional
> export PROJECT_HOME=$HOME/projects      # Optional
> source /home/vagrant/.local/bin/virtualenvwrapper.sh
> EOF

source ~/.bashrc

# Create a virtual environment
mkvirtualenv my_project
# Work on a virtual environment
workon my_project
# deactivate
deactivate
# delete
rmvirtualenv venv
# List all of the environments
lsvirtualenv
# Navigate into the directory of the currently activated virtual environment, so you can browse its site-packages
cdvirtualenv
# Shows contents of site-packages directory
lssitepackages
============================================================================
multiple ansible environments

sudo pip install virtualenv
sudo pip install virtualenvwrapper

cat >> ~/.profile << EOF
export WORKON_HOME=$HOME/.virtualenvs   # Optional
source /usr/local/bin/virtualenvwrapper.sh
EOF

mkvirtualenv ansible-latest
pip install ansible

mkvirtualenv ansible-2.7
pip install ansible==2.7

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vagrant@remotecontrol01:~$ hostnamectl
   Static hostname: remotecontrol01
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 596011e352744fafa2713e957add0deb
           Boot ID: 8c8d71d061ad4eb2b55b2c85881e030f
    Virtualization: oracle
  Operating System: Ubuntu 19.04
            Kernel: Linux 5.0.0-17-generic
      Architecture: x86-64

vagrant@remotecontrol01:~$ sudo apt install python-pip -y
vagrant@remotecontrol01:~$ sudo pip install virtualenv
vagrant@remotecontrol01:~$ sudo pip install virtualenvwrapper
vagrant@remotecontrol01:~$ python2 --version
Python 2.7.16
vagrant@remotecontrol01:~$ python3 --version
Python 3.7.3

vagrant@remotecontrol01:~$ virtualenv -p /usr/bin/python2.7 ~venv27
Running virtualenv with interpreter /usr/bin/python2.7
Already using interpreter /usr/bin/python2.7
New python executable in /home/vagrant/~venv27/bin/python2.7
Also creating executable in /home/vagrant/~venv27/bin/python
Installing setuptools, pip, wheel...
done.

vagrant@remotecontrol01:~$ virtualenv -p /usr/bin/python3.7 ~venv37
Running virtualenv with interpreter /usr/bin/python3.7
Already using interpreter /usr/bin/python3.7
Using base prefix '/usr'
New python executable in /home/vagrant/~venv37/bin/python3.7
Also creating executable in /home/vagrant/~venv37/bin/python
Installing setuptools, pip, wheel...
done.
vagrant@remotecontrol01:~$ sudo apt-get install python3-distutils -y

cat >> ~/.profile << EOF
export WORKON_HOME=$HOME/.virtualenvs   # Optional
source /usr/local/bin/virtualenvwrapper.sh
EOF
vagrant@remotecontrol01:~$ source .profile
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/premkproject
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/postmkproject
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/initialize
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/premkvirtualenv
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/postmkvirtualenv
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/prermvirtualenv
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/postrmvirtualenv
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/predeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/postdeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/preactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/postactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/get_env_details

vagrant@remotecontrol01:~$ python3 --version
Python 3.7.3
vagrant@remotecontrol01:~$ which python3
/usr/bin/python3

vagrant@remotecontrol01:~$ mkvirtualenv -p /usr/bin/python3 venv373
Running virtualenv with interpreter /usr/bin/python3
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /home/vagrant/.virtualenvs/venv373/bin/python3
Also creating executable in /home/vagrant/.virtualenvs/venv373/bin/python
Installing setuptools, pip, wheel...
done.
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv373/bin/predeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv373/bin/postdeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv373/bin/preactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv373/bin/postactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv373/bin/get_env_details
(venv373) vagrant@remotecontrol01:~$ ls -lai .virtualenvs/venv373/
total 16
3677748 drwxrwxr-x 4 vagrant vagrant 4096 Aug 29 13:58 .
3674757 drwxrwxr-x 5 vagrant vagrant 4096 Aug 29 13:58 ..
3677805 drwxrwxr-x 2 vagrant vagrant 4096 Aug 29 13:58 bin
3677749 drwxrwxr-x 3 vagrant vagrant 4096 Aug 29 13:58 lib
(venv373) vagrant@remotecontrol01:~$ ls -lai .virtualenvs/
total 68
3674757 drwxrwxr-x  5 vagrant vagrant 4096 Aug 29 13:58 .
3670052 drwxr-xr-x 10 vagrant vagrant 4096 Aug 29 13:43 ..
3674926 -rwxr-xr-x  1 vagrant vagrant  135 Aug 29 13:43 get_env_details
3674886 -rw-r--r--  1 vagrant vagrant   96 Aug 29 13:43 initialize
3674924 -rw-r--r--  1 vagrant vagrant   73 Aug 29 13:43 postactivate
3674903 -rw-r--r--  1 vagrant vagrant   75 Aug 29 13:43 postdeactivate
3674885 -rwxr-xr-x  1 vagrant vagrant   66 Aug 29 13:43 postmkproject
3674888 -rw-r--r--  1 vagrant vagrant   73 Aug 29 13:43 postmkvirtualenv
3674898 -rwxr-xr-x  1 vagrant vagrant  110 Aug 29 13:43 postrmvirtualenv
3674908 -rwxr-xr-x  1 vagrant vagrant   99 Aug 29 13:43 preactivate
3674902 -rw-r--r--  1 vagrant vagrant   76 Aug 29 13:43 predeactivate
3674877 -rwxr-xr-x  1 vagrant vagrant   91 Aug 29 13:43 premkproject
3674887 -rwxr-xr-x  1 vagrant vagrant  130 Aug 29 13:43 premkvirtualenv
3674895 -rwxr-xr-x  1 vagrant vagrant  111 Aug 29 13:43 prermvirtualenv
3674927 drwxrwxr-x  6 vagrant vagrant 4096 Aug 29 13:57 test1
3676723 drwxrwxr-x  6 vagrant vagrant 4096 Aug 29 13:57 test2
3677748 drwxrwxr-x  4 vagrant vagrant 4096 Aug 29 13:58 venv373
(venv373) vagrant@remotecontrol01:~$ deactivate
vagrant@remotecontrol01:~$ cd ~

vagrant@remotecontrol01:~$ which python2
/usr/bin/python2
vagrant@remotecontrol01:~$ python2 --version
Python 2.7.16

vagrant@remotecontrol01:~$ mkvirtualenv -p /usr/bin/python2 venv2716
Running virtualenv with interpreter /usr/bin/python2
Already using interpreter /usr/bin/python2
New python executable in /home/vagrant/.virtualenvs/venv2716/bin/python2
Also creating executable in /home/vagrant/.virtualenvs/venv2716/bin/python
Installing setuptools, pip, wheel...
done.
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv2716/bin/predeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv2716/bin/postdeactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv2716/bin/preactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv2716/bin/postactivate
virtualenvwrapper.user_scripts creating /home/vagrant/.virtualenvs/venv2716/bin/get_env_details
(venv2716) vagrant@remotecontrol01:~$ deactivate
vagrant@remotecontrol01:~$



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pip uninstall SomePackage
pip show sphinx
# list installed packages
pip list
# list outdated packages
pip list --outdated
# pip can search PyPI for packages
pip search "query"
# pip comes with support for command line completion in bash, zsh and fish.
pip completion --bash >> ~/.profile
pip completion --zsh >> ~/.zprofile
pip completion --fish > ~/.config/fish/completions/pip.fish

# you can use the result of the completion command directly with the eval function of your shel l
# e.g. by adding the following to your startup file
eval "`pip completion --bash`"

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vagrant@vgclient01:~/.virtualenvs/k8sbox1$ sudo docker -v
sudo: docker: command not found

vagrant@vgclient01:~/.virtualenvs/k8sbox1$ workon k8sbox1
(k8sbox1) vagrant@vgclient01:~/.virtualenvs/k8sbox1$ pwd
/home/vagrant/.virtualenvs/k8sbox1
(k8sbox1) vagrant@vgclient01:~/.virtualenvs/k8sbox1$
(k8sbox1) vagrant@vgclient01:~/.virtualenvs/k8sbox1$ sudo bash /vagrant/k8snodes.sh
(k8sbox1) vagrant@vgclient01:~/.virtualenvs/k8sbox1$ docker -v
Docker version 18.06.2-ce, build 6d37f41
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"pip install -e ."
installs site-packages/PackageName.egg-link file
adds path to site-packages/easy-install.pth
optionally installs CLI targets in <venv>/bin
how setuptools dependencies are handled via pip

install the dependencies
*[dev] is the name of the requirements group from setup.py
git clone URL
cd project
"pip install -e ." OR "pip install -e .[dev]*"

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#pycharm scrapy install
File - Setting - Project: your_project_name -  Project Interpreter -  “+” - Type there scrapy - Install Package

Pycharm Terminal - pip3 install Scrapy (For python 3.xx)
Pycharm Terminal - pip install Scrapy (For python 3.xx)
scrapy --version
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$ hostnamectl
  Operating System: CentOS Linux 8
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-240.1.1.el8_3.x86_64
      Architecture: x86-64

#install python 3x
yum install python3
python3 -V
pip3 --version

pip3 install --user virtualenv
virtualenv --version

#create python3 virtual environment
virtualenv venv3 --python=`which python3`
cd venv3/bin/
$ source activate
$ python -V
Python 3.6.8
$ python3 -V
Python 3.6.8
$ python2 -V
Python 2.7.18
$ pip --version
pip 21.3.1 from /home/vagrant/venv3/lib/python3.6/site-packages/pip (python 3.6)
$ pip3 --version
pip 21.3.1 from /home/vagrant/venv3/lib/python3.6/site-packages/pip (python 3.6)
$ pip2 --version
pip 9.0.3 from /usr/lib/python2.7/site-packages (python 2.7)
$ deactivate

#install python 2x
yum install python2
python2 -V

#create python2 virtual environment
cd venv2/bin
source activate
$ python -V
Python 2.7.18
$ python3 -V
Python 3.6.8
$ python2 -V
Python 2.7.18
$ pip --version
pip 20.3.4 from /home/vagrant/venv2/lib/python2.7/site-packages/pip (python 2.7)
$ pip3 --version
pip 21.3.1 from /home/vagrant/venv3/lib/python3.6/site-packages/pip (python 3.6)
$ pip2 --version
pip 9.0.3 from /usr/lib/python2.7/site-packages (python 2.7)
$ deactivate

============================================================================
$ hostnamectl
  Operating System: CentOS Linux 8
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-240.1.1.el8_3.x86_64
      Architecture: x86-64
      
yum install python2
pip2 --version

pip install virtualenv
============================================================================