second commit

tools/append_or_replace

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+usage() {
+	echo "Usage: $(basename "$0") <REGEX> <STRING> <FILE>"
+}
+
+if [[ $# -ne 3 ]]; then
+	usage
+	exit 2
+fi
+
+REGEX=$1
+STRING=$2
+FILE=$3
+
+if ! grep -Eq "$REGEX" "$FILE"; then
+	printf "$STRING\n" >>$FILE
+	echo appended
+else
+	sed -Ei "s|$REGEX|$STRING|g" $FILE
+	echo replaced
+fi