I’m using phing to automate a deploy of a php web application to production, phing is a really powerful tool (and easy to use), AdhocTaskdefTask allow to implement custom tags with input and output parameters, for example, I needed to adjust some relative path in production, there’s a simple adhoc task to get the new paths:

<!--
    Usage:
    <relative-path from="${from}" to="${to}"
        output="project_property" />
-->
<adhoc-task name="relative-path"><![CDATA[
    class RelativePath extends Task {
        private $from;
        private $to;
        private $output;

        function setFrom($from) {
            $this->from = $from;
        }

        function setTo($to) {
            $this->to = $to;
        }

        function setOutput($output=null) {
            $this->output = $output;
        }

        function main() {
            $relpath = $this->find_relative_path($this->from, $this->to);
            $this->log("relpath = " . $relpath);
            if ($this->output != null) {
                $this->project->setProperty($this->output, $relpath);
            }
        }

        /**
         * credits: https://gist.github.com/ohaal/2936041
         * Find the relative file system path between two file system paths
         *
         * @param  string  $frompath  Path to start from
         * @param  string  $topath    Path we want to end up in
         *
         * @return string             Path leading from $frompath to $topath
         */
        function find_relative_path ( $frompath, $topath ) {
            $from = explode( DIRECTORY_SEPARATOR, $frompath ); // Folders/File
            $to = explode( DIRECTORY_SEPARATOR, $topath ); // Folders/File
            $relpath = '';

            $i = 0;
            // Find how far the path is the same
            while ( isset($from[$i]) && isset($to[$i]) ) {
                if ( $from[$i] != $to[$i] ) break;
                $i++;
            }
            $j = count( $from ) - 1;
            // Add '..' until the path is the same
            while ( $i <= $j ) {
                if ( !empty($from[$j]) ) $relpath .= '..'.DIRECTORY_SEPARATOR;
                $j--;
            }
            // Go to folder from where it starts differing
            while ( isset($to[$i]) ) {
                if ( !empty($to[$i]) ) $relpath .= $to[$i].DIRECTORY_SEPARATOR;
                $i++;
            }

            // Strip last separator
            return substr($relpath, 0, -1);
        }
    }
]]></adhoc-task>