How to install git on linux

#!/bin/bash
source ./cnl_function.sh

#function of installing git
install_git(){
  #download the compressed package
  cd /usr/local/src
  #if compressed package is empty then download
  [ -f git-2.2.1.tar.gz ] || wget https://www.kernel.org/pub/software/scm/git/git-2.2.1.tar.gz
  check_ok

  tar -zxf git-2.2.1.tar.gz
  check_ok

  [ -d /usr/local/git ] && mv /usr/local/git /usr/local/git_`date +%s`  
  cd git-2.2.1
  check_ok
  
  for p in expat-devel 
  do 
    myum $p
  done

  make prefix=/usr/local/git all
  make prefix=/usr/local/git install
  check_ok
  
  if ! grep '^git:' /etc/group
  then 
    groupadd git
  fi  
  
  if ! grep '^git:' /etc/passwd
  then
    useradd -m git -s /usr/local/git/bin/git-shell -g git
  fi  
  check_ok
  ln -s /usr/local/git/bin/git /usr/local/bin/git
  
  echo "git is installed finish."  
}

read -p "Enter (Y) to start installation git:" n
if [ $n == 'Y' ]
then 
  echo "Start installation==========================================================================================================================================================>"
  install_git
else 
  echo "Cancel the installation."
fi

git --version