-cat $TRACE | eval grep $GREP2 > types
-/bin/sed -e "$GREP" $TRACE > events
-cat events | sort -n -k 2 -s > events.sorted
-cat header types events.sorted > $OUTPUT
-rm types events events.sorted header
+grep "${GREP[@]}" -- "$TRACE" > types
+grep -v "${GREP2[@]}" -- "$TRACE" > events
+sort -n -k 2 -s < events > events.sorted
+cat header types events.sorted > "$OUTPUT"
+rm -f types events events.sorted header