Added help message

expandcidr.sh

@@ -1,13 +1,39 @@
-# $1 - input filename  
-# $2 - output filename  
-# $3 - Randomize output number  
+Help()
+{
+    echo ""
+    echo "No arguments supplied - take this:"
+    echo ""
+    echo "expandcidr - A file with a scope list in CIDR notation is expanded "
+    echo "             to all possible IPs. It can also output instead a"
+    echo "▅▅▅▅▅▅▅▅▅    a specified number of unique random IPs from the output"
+    echo "▅▅▅▅▅▅▅▅▅    file (useful for sample testing, for ex.)."
+    echo "▅▅▅▅▅▅▅▅▅    Script leverages on nmap - same scope list format"
+    echo "▅▅▅▅ ▅▅▅▅ "               
+    echo "▅▅▅▅▅▅▅▅▅    Example: expandcidr scope.txt output.txt 4000" 
+    echo ""
+    echo "Usage: expandcidr [input file] [output file] [optional-rnd-#-ips]"
+    echo ""
+    echo ""
+}
 
-# Help  
+while getopts ":h" option; do
+   case $option in
+      h) # display Help
+         Help
+         exit;;
+   esac
+done
 
-  
-if [ -z "$3"]  
-   then  
-       nmap -sL -n -iL $1 | grep 'Nmap scan report for' | cut -f 5 -d ' ' > $2  
-   else  
-       nmap -sL -n -iL $1 | grep 'Nmap scan report for' | cut -f 5 -d ' ' | shuf -n $3 > $2  
+if [ $# -eq 0 ]
+  then Help
+    exit 1
+fi
+
+# command chain
+
+if [ -z $3 ]
+    then
+        nmap -sL -n -iL $1 | grep 'Nmap scan report for' | cut -f 5 -d ' ' > $2
+    else
+        nmap -sL -n -iL $1 | grep 'Nmap scan report for' | cut -f 5 -d ' ' | shuf -n $3 > $2
 fi