Below is a simple Shell Script I wrote that creates a copy of a directory and minifies all of the PHP files within it.

#!/bin/sh

# set source directory
if [ "$1" = "" ]  
then  
  echo "Usage: $0 <source directory>"
  exit
fi

COUNT=0;  
SOURCE_DIR="$1"  
DEST_DIR="$1-minified"

# create destination directory and copy source files
rm -Rf ${DEST_DIR}  
mkdir ${DEST_DIR}  
cp -r "./${SOURCE_DIR}" "./${DEST_DIR}/${SOURCE_DIR}"

# iterate through php source files, compressing them and writing the output to the destination
for FILENAME in `echo $(find ${SOURCE_DIR} -name "*.php")`  
do  
    COUNT=$((COUNT+1))
    php -w ./${FILENAME} > ./${DEST_DIR}/${FILENAME}
done

sizeBefore=$(du -h -c ${SOURCE_DIR} | tail -1 | tr -d 'total' | tr -d ' ');  
sizeAfter=$(du -h -c ${DEST_DIR} | tail -1 | tr -d 'total' | tr -d ' ');

# finished
echo "Finished - $COUNT PHP files minified"  
echo "Size Before: $sizeBefore"  
echo "Size After: $sizeAfter"  

Example usage, passing in the source directory, Moustache

$ ./php-minify.sh Mustache
Finished - 32 PHP files minified  
Size Before: 184K  
Size After: 144K  

It automatically creates a new directory for the minified version, Mustache-minified

$ ls -1
Mustache  
Mustache-minified