Automated Wordpress updates from the command line

update_wordpress.sh

#!/bin/bash
wp_dir=$1
backup_dir=$2
latest_version=`echo -e "HEAD /latest.tar.gz HTTP/1.1\nHost: wordpress.org\n\n" | \
                nc -i 1 wordpress.org 80 | \
                grep 'Content-Disposition:' | \
                sed 's:.*filename=[A-Za-z-]*\([0-9\.]*\)\.tar\.gz.*:\1:'`
current_version=`grep '$wp_version = ' ${wp_dir}/wp-includes/version.php | \
                 sed "s:.*['\"]\([0-9\.]*\)['\"].*:\1:"`

function version_cmp {
 return `echo "$2 $1" | \
         awk '{
               split($1, a, ".");
               split($2, b, ".");
               x = 0;
               for (i = 1; i <= 4; i++)
                 if (a[i] < b[i]) {
                   x =-1;
                   break;
                 } else if (a[i] > b[i]) {
                   x = 1;
                   break;
                 }
               print x;
              }'`
}

echo "Current version: $current_version"
echo "Latest version:  $latest_version"

version_cmp $current_version $latest_version
difference=$?

if [ "$difference" -le "0" ]
then

  echo "Already at the latest version."
  exit 0
elif [ "$difference" -gt "0" ]
then
  backup_file=$backup_dir/`date "+%F-%H-%M-%S"`.tar.gz
  echo "Backing up to $backup_file."

  db_user=`grep "define('DB_USER'" ${wp_dir}/wp-config.php | \
           sed "s:.*define[ \t]*(['\"][^'\"]*['\"][ \t]*,[ \t]*['\"]\([^'\"]*\).*:\1:"`
  db_pass=`grep "define('DB_PASSWORD'" ${wp_dir}/wp-config.php | \
           sed "s:.*define[ \t]*(['\"][^'\"]*['\"][ \t]*,[ \t]*['\"]\([^'\"]*\).*:\1:"`
  db_name=`grep "define('DB_NAME'" ${wp_dir}/wp-config.php | \
           sed "s:.*define[ \t]*(['\"][^'\"]*['\"][ \t]*,[ \t]*['\"]\([^'\"]*\).*:\1:"`
  db_host=`grep "define('DB_HOST'" ${wp_dir}/wp-config.php | \
           sed "s:.*define[ \t]*(['\"][^'\"]*['\"][ \t]*,[ \t]*['\"]\([^'\"]*\).*:\1:"`
  db_prefix=`egrep "table_prefix\s*=" ${wp_dir}/wp-config.php | \
             sed "s:^.*table_prefix[ \t]*=[ \t]*['\"]\([^'\"]*\).*:\1:"`

  sql_file=$wp_dir/`date "+%F-%H-%M-%S"`.sql
  mysqldump -h$db_host -u$db_user --password="$db_pass" $db_name > $sql_file
  tar -cz -C `dirname $wp_dir` -f $backup_file `basename $wp_dir`
  rm $sql_file

  echo "Downloading Wordpress $latest_version."
  download_file=`mktemp`
  wget -q http://wordpress.org/latest.tar.gz -O $download_file
  echo "Extracting downloaded archive..."
  strip_arg="--strip-path"
  version_cmp "1.14.90" "`tar --version | head -n 1 | egrep -o '[0-9\.]*$'`"
  tar_version=$?
  if [ "$tar_version" -gt "0" ]
  then
     strip_arg="--strip-components"
  fi
  tar -zx $strip_arg 1 -C $wp_dir -f $download_file
  rm $download_file

  wp_siteurl=`mysql -h$db_host -u$db_user -p$db_pass $db_name -s -r \
                    --execute="select option_value
                               from ${db_prefix}options
                               where option_name='siteurl';" | \
              grep -v 'option_value'`

  echo "Checking if data update required..."
  # Need to log in for this to work
  update_page=`wget -q $wp_siteurl/wp-admin/upgrade.php -O -`
  if [ `echo $update_page | grep 'No Update Required'` ]
  then
    # Update required

    echo "Data update is required."
  elif [ `echo $update_page | grep 'You cannot update'` ]
  then
    echo "Manual update required."
  else
    echo "No further update required."
  fi
  echo "Manual update may be required. Visit $wp_siteurl/wp-admin/upgrade.php" | \
       mail -s "Wordpress at $wp_siteurl updated to $latest_version" root
fi