backup.sh

#!/bin/bash

GIT_LOCATION=$HOME/git/archlinux-homepc
GITHUB_USR=interskh

# backup packages
# @see https://wiki.archlinux.org/index.php/Pacman_Tips#Backing_up_and_retrieving_a_list_of_installed_packages
# @param GITHUB_USR optional, the user name of github.com. If empty, only local backup
function backup_archlinux_packages_list() {
   mkdir -p $GIT_LOCATION
   comm -23 <(pacman -Qeq|sort) <(pacman -Qmq|sort) > $GIT_LOCATION/pkglist.txt
   if [ ! -e $GIT_LOCATION/README.org ]; then
      echo "* My ArchLinux packages list " > $GIT_LOCATION/README.org
   fi
   local GIT=`/usr/bin/which git`

   if [ "${GIT}x" = "x" ]; then
      echo Git not found! You need to install git first.
      return 0
   fi

   cd $GIT_LOCATION
   if [ ! -d $GIT_LOCATION/.git ]; then
      #first import
      $GIT init
      $GIT add $GIT_LOCATION/pkglist.txt $GIT_LOCATION/README*
      $GIT commit -m 'first import'
      if [ ! "${GITHUB_USR}x" = "x" ]; then
         $GIT remote add origin "git@github.com:${GITHUB_USR}/archlinux-${HOSTNAME}.git"
         $GIT push -u origin master
      fi
   else
      # normal commit
      local gd=`${GIT} diff .`
      if [ ! "${gd}x" == "x" ]; then
         # only add files already under track
         $GIT add -u .
         $GIT commit -m `date +%H%M%S-%Y-%m-%d`
         if [ "${GITHUB_USR}" != "" ]; then
            $GIT push origin master
         fi
      fi
   fi
   cd $HOME
   return 0
}

backup_archlinux_packages_list