spice-example-sh: add parameter parser

As suggested by Michael in the forum.

spice-example-sh

@@ -2,13 +2,60 @@
 
 # needs pve-manager >= 3.1-44
 
-USERNAME=root@pam
-PASSWORD=yoursecretpassword
-# select VM
-VMID=100
+usage() { 
+    echo "Usage: $0 [-u <string>] [-p <string>] vmid [node [proxy]]"
+    echo
+    echo "-u username. Default root@pam"
+    echo "-p password. Default ''"
+    echo
+    echo "vmid: id for VM"
+    echo "node: Proxmox cluster node name"
+    echo "proxy: DNS or IP (use <node> as default)"
+    exit 1
+}
 
-NODE=anodename
-PROXY=anodename.domain.tld
+PASSWORD=""
+USERNAME=""
+
+while getopts ":u:p:" o; do
+    case "${o}" in
+        u)
+            USERNAME=${OPTARG}
+            ;;
+        p)
+            PASSWORD=${OPTARG}
+            ;;
+        *)
+            usage
+            ;;
+    esac
+done
+
+shift $((OPTIND-1))
+
+if [ -z $PASSWORD ]; then
+    PASSWORD=""
+fi
+if [ -z $USERNAME ]; then
+    USERNAME=root@pam
+fi
+
+DEFAULTHOST=$(hostname -f)
+
+# select VM
+[ -z $1 ] && usage
+VMID=$1
+
+#[ -z $2 ] && usage
+NODE=${2:-$DEFAULTHOST}
+
+if [ -z $3 ]; then
+    PROXY=$NODE
+else
+    PROXY=$3
+fi
+
+NODE=${NODE%%\.*}
 
 DATA=`curl -k -d "username=$USERNAME&password=$PASSWORD"  https://$PROXY:8006/api2/json/access/ticket`