Automating Python installation

A simple Bash script to download, compile, and install a specific version of Python from source on Linux systems (e.g. Rocky, CentOS, AlmaLinux, RHEL, Ubuntu, Debian).

Ideal for developers or sysadmins who need to manage multiple Python versions without affecting the system default.

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Problem

In Linux environments, installing python is a common task. However, doing it manually can be time consuming.

Goal

To reduce repetition by automating the get-python process, while still allowing manual override when needed.

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Features

• Download official Python tarballs from python.org
• Automatically install system dependencies (on supported RPM & DEB based systems)
• Compile with --enable-optimizations for better performance
• Logs progress with clean, readable output
• Error handling with helpful messages

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Script Example

Create a file named get-python.sh and paste the following:

#!/bin/bash
# Python script installer
set -euo pipefail
IFS=$'\n\t'

HELP_TEXT="
Usage: bash getpython.sh [--version VERSION]

Options:
  --version               Which python version you'd like to install (e.g. 3.6.5, 3.9.5, 3.11.0)
  --help, -h              Show this help message
"

## Getting the user input
while [[ "$#" -gt 0 ]]; do
  case $1 in
    --help|-h)
    echo "$HELP_TEXT"
    exit 0
    ;;
    --version) VERSION="$2"; shift 2 ;;
    *) echo "Unknown option: $1" ;;
  esac
done

REPO_URL="https://www.python.org/ftp/python"
INSTALL_DIR="/tmp/getpython"
VERSION="${VERSION:-}"
PYTHON_TARBALL_NAME="Python-${VERSION}.tgz"
PYTHON_TARBALL_PATH="${INSTALL_DIR}/${PYTHON_TARBALL_NAME}"
PYTHON_TARBALL_URL="${REPO_URL}/${VERSION}/${PYTHON_TARBALL_NAME}"

DEPENDENCY_PKGS=(curl tar wget openssl-devel bzip2-devel zlib-devel libffi-devel make gcc)
declare -A REQPKGS
REQPKGS["openssl-devel"]="libssl-dev"
REQPKGS["zlib-devel"]="zlib1g-dev"
REQPKGS["bzip2-devel"]="libbz2-dev"
REQPKGS["libffi-devel"]="libffi-dev"


function log() {
  if [[ -n "${LOG:-}" ]]; then
    printf '%s\n' "$*" | tee -a "$LOG" >&2
  else
    printf '%s\n' "$*" >&2
  fi
}
function fatal() { log "ERROR: $*"; exit 1; }

# Check supported OS versions
function detect_os_version() {
OS_VER=$(awk -F= '/^ID=/{print $2}' /etc/os-release | tr -d '"')

case "$OS_VER" in
  rhel|centos|rocky|almalinux|ubuntu|debian) ;;
  *) fatal "Unsupported distro: $OS_VER";;
esac
}

# Supported packaged manager
function check_pkg_manager() {
  if [[ $OS_VER =~ (rhel|centos|rocky|almalinux) ]]; then
    PKG_MGR=$(command -v dnf || command -v yum)
    [[ -x $PKG_MGR ]] || fatal "command dnf/yum not found"
  else
    PKG_MGR=$(command -v apt || command -v apt-get)
    [[ -x $PKG_MGR ]] || fatal "command apt/apt-get not found"
  fi
}

# Install packages needed
function need_pkgs() {
    local missing=()
    if [[ $PKG_MGR =~ (yum|dnf) ]]; then
      for pkgs in "$@"; do 
          rpm -q "$pkgs" &>/dev/null || missing+=("$pkgs")
      done
    elif [[ $PKG_MGR =~ (apt|apt-get) ]]; then
      for pkgs in "$@"; do
        mapped_pkg="${REQPKGS[$pkgs]:-$pkgs}"
        dpkg -s "$mapped_pkg" &>/dev/null || missing+=("$mapped_pkg")
      done
    fi

    if ((${#missing[@]})); then
        "$PKG_MGR" -y install "${missing[@]}" &>/dev/null
    else
        log "INFO: All requested packages already present."
    fi
}

# If dir doesn't exist create it
function check_install_path() {
  if [[ ! -e ${INSTALL_DIR} ]]; then
    log "INFO: Install path doesn't exist, creating it on ${INSTALL_DIR}."
    mkdir -p "${INSTALL_DIR}"
  else
    log "INFO: Dir ${INSTALL_DIR} already exist, skip creating."
  fi
}

# Download from official repository
function download_tarball() {
  log "INFO: Downloading the Python ${VERSION} tarball."
  curl -o "$PYTHON_TARBALL_PATH" "$PYTHON_TARBALL_URL" || \
  wget -O "$PYTHON_TARBALL_PATH" "$PYTHON_TARBALL_URL" || \
  fatal "Failed to download Python ${VERSION}."
}

# skip if tarball exist, else download tarball
function fetch_and_extract_tarball() {
  if [[ -f "$PYTHON_TARBALL_PATH" ]]; then
    log "INFO: Python ${VERSION} tarball already exists. Skipping download."
  else
    download_tarball
  fi

  log "INFO: Extracting the Python ${VERSION} tarball."
  tar -xf "$PYTHON_TARBALL_PATH" --overwrite -C ${INSTALL_DIR} || \
  fatal "File doesn't exist, exiting the script"
}

# Install requested python
function install_python() {
  log "INFO: Compiling and install Python ${VERSION}."
  ${INSTALL_DIR}/Python-"${VERSION}"/configure --enable-optimizations
  make altinstall && log "Python ${VERSION} successfully installed."
}

function main() {
  log "INFO: Starting the script ..."
  detect_os_version
  check_pkg_manager

  log "INFO: Installing required packages."
  need_pkgs "${DEPENDENCY_PKGS[@]}"

  check_install_path
  fetch_and_extract_tarball
  install_python || fatal "Failed to install Python ${VERSION}."
}

# Validate the user input
if [[ -z "${VERSION:-}" ]]; then
  echo "ERROR: --version is required"
  echo "$HELP_TEXT"
  exit 1
fi

main

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Usage

bash get-python.sh --version <python_version>

Example:

bash get-python.sh --version 3.11.0

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Requirements

• Rocky Linux, AlmaLinux, RHEL, CentOS
• dnf, yum or apt as package manager
• Root/sudo access (to install dependencies)

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What It Does

1. Detects supported Linux distribution
2. Installs required development packages
3. Downloads the specified Python version
4. Compiles and installs it using make altinstall
5. Outputs success or error messages

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Install Path

By default, all operations happen inside:

/tmp/getpython

You can edit the DEFAULT_INSTALL_PATH variable inside the script to change this.

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Installed Dependencies

The script installs the following packages (if missing):

• gcc
• make
• curl
• tar
• wget
• zlib-devel
• openssl-devel
• bzip2-devel
• libffi-devel
• readline-devel
• xz-devel
• sqlite-devel

These are required to properly compile and run Python from source.

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Future Improvements

• Add --prefix option for custom install locations
• Add --force flag to re-download or overwrite

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