diff --git a/pmd/bin/cpd.sh b/pmd/bin/cpd.sh
index 422388f935..89aff04685 100755
--- a/pmd/bin/cpd.sh
+++ b/pmd/bin/cpd.sh
@@ -11,76 +11,107 @@
 ## If you run into java.lang.OutOfMemoryError, try setting the environment
 ## variable HEAPSIZE to e.g. 512m
 
-DIRECTORY=$1
+usage() {
+    echo "Usage:"
+    echo "$(basename ${0})  <source-directory> [--ignore-literals] [--ignore-identifiers]"
+    echo ""
+    echo "Set language with environment variable LANGUAGE ($(supported_languages))"
+}
 
-if [ -z "$1" ]; then
-				script=`basename $0`
-				echo "Usage:"
-				echo " $script <directory>"
-				exit 1
+supported_languages() {
+    echo "c, cpp, fortran, java, jsp, php, ruby"
+}
+
+is_cygwin() {
+    case "$(uname)" in
+        CYGWIN*)
+            readonly cygwin=true
+            ;;
+    esac
+    # OS specific support.  $var _must_ be set to either true or false.
+    if [ -z ${cygwin} ] ; then
+        readonly cygwin=false
+    fi
+}
+
+convert_cygwin_vars() {
+    # If cygwin, convert to Unix form before manipulating
+    if $cygwin ; then
+        [ -n "${JAVA_HOME}" ] &&
+            JAVA_HOME=$(cygpath --unix "${JAVA_HOME}")
+        [ -n "${CLASSPATH}" ] &&
+            CLASSPATH=$(cygpath --path --unix "${CLASSPATH}")
+    fi
+}
+
+cygwin_paths() {
+    # For Cygwin, switch paths to Windows format before running java
+    if ${cygwin} ; then
+        JAVA_HOME=$(cygpath --windows "${JAVA_HOME}")
+        classpath=$(cygpath --path --windows "${classpath}")
+        DIRECTORY=$(cygpath --windows "${DIRECTORY}")
+    fi
+}
+
+language_settings() {
+    readonly LANGUAGE=${LANGUAGE:-cpp}
+    case "${LANGUAGE}" in
+        c|cpp|fortran|java|jsp|php|ruby)
+            echo "Language is set to ${LANGUAGE}"
+            ;;
+        *)
+            echo "Language '${LANGUAGE}' unknown (try: $(supported_languages))"
+            exit 1
+    esac
+}
+
+java_heapsize_settings() {
+    local heapsize=${HEAPSIZE:-512m}
+    case "${heapsize}" in
+        [1-9]*[mgMG])
+            readonly HEAPSIZE="-Xmx${heapsize}"
+            ;;
+        '')
+            ;;
+        *)
+            echo "HEAPSIZE '${HEAPSIZE}' unknown (try: 512m)"
+            exit 1
+    esac
+}
+
+DIRECTORY=${1}
+
+if [ -z "${DIRECTORY}" ]; then
+	usage
+    exit 1
 fi
 shift
 
-# OS specific support.  $var _must_ be set to either true or false.
-cygwin=false;
-case "`uname`" in
-  CYGWIN*) cygwin=true ;;
-esac
+is_cygwin
 
-SCRIPT_DIR=`dirname $0`
-CWD="$PWD"
+readonly SCRIPT_DIR=$(dirname ${0})
+CWD="${PWD}"
 
-cd "$SCRIPT_DIR/../lib"
-LIB_DIR=`pwd -P`
+cd "${SCRIPT_DIR}/../lib"
+readonly LIB_DIR=$(pwd -P)
 
-# If cygwin, convert to Unix form before manipulating
-if $cygwin ; then
-  [ -n "$JAVA_HOME" ] &&
-    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
- [ -n "$CLASSPATH" ] &&
-    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
-fi
+convert_cygwin_vars
 
-classpath=$CLASSPATH
+classpath="${CLASSPATH}"
 
-build_dir="$SCRIPT_DIR/../build"
-
-if [ -d "$build_dir" ]; then
-				cd "$build_dir"
-				build_dir=`pwd -P`
-				classpath=$classpath:$build_dir
-fi
-
-cd "$CWD"
-
-for jarfile in `ls $LIB_DIR/*.jar`; do
-				classpath=$classpath:$jarfile
+cd "${CWD}"
+for jarfile in ${LIB_DIR}/*.jar; do
+    classpath=${classpath}:${jarfile}
 done
 
-HEAPSIZE=${HEAPSIZE:-512m}
-LANGUAGE=${LANGUAGE:-cpp}
-MINIMUM_TOKENS=${MINIMUM_TOKENS:-100}
+java_heapsize_settings
 
-case "$HEAPSIZE" in
-[1-9]*[mgMG]) HEAPSIZE=-Xmx$HEAPSIZE ;;
-'') ;;
-*) echo "HEAPSIZE '$HEAPSIZE' unknown (try: 512m)"
-   exit 1
-esac
+language_settings
 
-case "$LANGUAGE" in
-c|cpp|fortran|java|jsp|php|ruby) ;;
-*) echo "Language '$LANGUAGE' unknown (try: c, cpp, fortran, java, jsp, php, ruby)"
-   exit 1
-esac
+cygwin_paths
 
-# echo "CLASSPATH: $classpath"
-
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin; then
-  JAVA_HOME=`cygpath --windows "$JAVA_HOME"`
-  classpath=`cygpath --path --windows "$classpath"`
-  DIRECTORY=`cygpath --windows "$DIRECTORY"`
-fi
-
-java $HEAPSIZE -cp $classpath net.sourceforge.pmd.cpd.CPD --minimum-tokens $MINIMUM_TOKENS --files $DIRECTORY --language $LANGUAGE ${@}
+java "${HEAPSIZE}" -cp "${classpath}" net.sourceforge.pmd.cpd.CPD \
+    --minimum-tokens "${MINIMUM_TOKENS:-100}"\
+    --files "${DIRECTORY}" \
+    --language "${LANGUAGE}" \
+    ${@}