diff --git a/impagina b/impagina
index 2ff5337..6e4d219 100755
--- a/impagina
+++ b/impagina
@@ -1,27 +1,59 @@
 #!/bin/sh
 
-# Initialize variables
-input="$1"
-inputMul4="/tmp/${input%.pdf}-Mul4.pdf"
-outputImpaginato="${input%.pdf}-Impaginato.pdf"
-empty="/tmp/empty.pdf"
-n="$(pdftk "$input" dump_data | grep NumberOfPages | cut -d' ' -f2)"
-
-# Add empty pages
-echo .bp | groff -T pdf > "$empty"
-
-pdftk F="$input" E="$empty" cat F1-$n $(for x in $(seq 1 $((4-n%4))); do printf 'E1 '; done) output "$inputMul4"
-
-# Generate alternating page ranges
-n=$((n+(4-n%4)))
-range=
-k=1
-while [ "$k" -lt $((n/2)) ]; do
-	range="$range$k $((n/2+k)) $((n/2+k+1)) $((k+1)) "
-	k=$((k+2))
-done
-
-# Output final pdf
-pdftk "$inputMul4" cat $range output "$outputImpaginato"
-
-rm "$empty" "$inputMul4"
+usage() {
+	_name="$(basename "$0")"
+	cat << EOF
+Utilizzo: ${_name} [nomePDF]
+
+Esempi:
+
+	${_name} MeccanicaRazionale.pdf
+
+Per bug contattare f.minnocci@studenti.unipi.it
+I ringraziamenti per l'idea originale vanno a http://poisson.phc.dm.unipi.it/~dilillo
+EOF
+exit $1
+}
+
+main() {
+	# Initialize variables
+	input="$(realpath "$1")"
+	basename="$(basename "$1")"
+	inputMul4="/tmp/${basename%.pdf}-Mul4.pdf"
+	outputImpaginato="${basename%.pdf}-Impaginato.pdf"
+	empty="/tmp/empty.pdf"
+	echo "$input $basename $inputMul4 $outputImpaginato" > ~/log
+	n="$(pdftk "$input" dump_data | grep NumberOfPages | cut -d' ' -f2)"
+
+	# Add empty pages
+	echo .bp | groff -T pdf > "$empty"
+
+	pdftk F="$input" E="$empty" cat F1-$n $(for x in $(seq 1 $((4-n%4))); do printf 'E1 '; done) output "$inputMul4"
+
+	# Generate alternating page ranges
+	n=$((n+(4-n%4)))
+	range=
+	k=1
+	while [ "$k" -lt $((n/2)) ]; do
+		range="$range$k $((n/2+k)) $((n/2+k+1)) $((k+1)) "
+		k=$((k+2))
+	done
+
+	# Output final pdf
+	pdftk "$inputMul4" cat $range output "$outputImpaginato"
+
+	rm "$empty" "$inputMul4"
+}
+
+if [ -z "$1" ] ; then
+	printf "Non hai specificato nessun file...\n\n" && usage 1
+else
+	case "$1" in
+	-h|--help)
+		usage 0 ;;
+	-*)
+		error "Opzione invalida: $1" ;;
+	*)
+		main "$@" ;;
+	esac
+fi