Add a variety of options to the main script

The options added are:
 -p, --pokemon POKEMON_NAME
 -f, --file COW_FILE
 -n, --no-name
 -h, --help

install.sh

@@ -24,7 +24,7 @@ cat > $bin_path/$bin_name <<- EOF
 
 	current_path=`pwd`
 	cd $install_path/
-	./pokemonsay.sh
+	./pokemonsay.sh \$@
 	cd \$current_path
 EOF
 

pokemonsay.sh

@@ -1,17 +1,85 @@
 #!/bin/sh
 
-# Define where the pokemon are.
+usage() {
+	echo
+	echo "  Description: Pokemonsay makes a pokémon say something to you."
+	echo
+	echo "  Usage: $(basename $0) [-p POKEMON_NAME] [-f COW_FILE] [-n] [-h] [MESSAGE]"
+	echo
+	echo "  Options:"
+	echo "    -p, --pokemon POKEMON_NAME"
+	echo "      Choose what pokemon will be used by its name."
+	echo "    -f, --file COW_FILE"
+	echo "      Specify which .cow file should be used."
+	echo "    -n, --no-name"
+	echo "      Do not tell the pokémon name."
+	echo "    -h, --help"
+	echo "      Display this usage message."
+	echo "    MESSAGE"
+	echo "      What the pokemon will say. If you don't provide a message, a message will be read form standard input."
+	exit 1
+}
+
+# While there are arguments, keep reading them.
+while [ $# -gt 0 ]
+do
+key="$1"
+case $key in
+	-p|--pokemon)
+		POKEMON_NAME="$2"
+		shift; shift
+		;;
+	-p=*|--pokemon=*)
+		POKEMON_NAME="${1#*=}"
+		shift
+		;;
+	-f|--file)
+		COW_FILE="$2"
+		shift; shift
+		;;
+	-f=*|--file=*)
+		COW_FILE="${1#*=}"
+		shift
+		;;
+	-n|--no-name)
+		DISPLAY_NAME="NO"
+		shift
+		;;
+	-h|--help)
+		usage
+		;;
+	*)
+		# Append this word to the message.
+		if [ -n "$MESSAGE" ]; then
+			MESSAGE="$MESSAGE $1"
+		else
+			MESSAGE="$1"
+		fi
+		shift
+		;;
+esac
+done
+
+# Where the pokemon are.
 pokemon_path=`pwd`/cows
 
-# Find all pokemon in the pokemon path and choose a random one.
-pokemon=$(find $pokemon_path -name "*.cow" | shuf -n1)
+# Define which pokemon should be displayed.
+if [ -n "$POKEMON_NAME" ]; then
+	pokemon_cow=$(find $pokemon_path -name "$POKEMON_NAME.cow")
+elif [ -n "$COW_FILE" ]; then
+	pokemon_cow="$COW_FILE"
+else
+	pokemon_cow=$(find $pokemon_path -name "*.cow" | shuf -n1)
+fi
 
 # Get the pokemon name.
-filename=$(basename "$pokemon")
+filename=$(basename "$pokemon_cow")
 pokemon_name="${filename%.*}"
 
 # Call cowsay.
-cowsay -f $pokemon
+cowsay -f "$pokemon_cow" "$MESSAGE"
 
-# Write the pokemon name.
-echo $pokemon_name
+# Write the pokemon name, unless requested otherwise.
+if [ -z "$DISPLAY_NAME" ]; then
+	echo $pokemon_name
+fi