readme 8

README.md

@@ -11,3 +11,48 @@ Instances of Ubuntu Linux with [MPICH](https://www.mpich.org) -- portable implem
 
 
 [inspired by NLKNguyen](https://github.com/NLKNguyen/alpine-mpich)
+
+
+## Quickstart
+
+This is a quickstart guide of how you can typically use this *LabInstance to deploy MPI programs*
+
+- Working Directory
+
+> /project
+
+- Default user for MPI
+
+> mpi
+
+- The host file that contains addresses of connected workers can created with:
+
+> IP_ADDR=$(ip addr show | grep "inet " | grep  "eth0" | awk '{print $2}')
+> nmap -sP $IP_ADDR  | grep ondemand_mpi_worker | awk  -F "[()]" '{ for (i=2; i<NF; i+=2) print $i }' > /project/hosts
+
+- Compile
+
+> mpicc -o /project/mpi_hello_world examples/mpi_hello_world.c
+
+- run the MPI hello world program
+
+sudo -u mpi mpirun -n 10 -f /project/hosts  /project/mpi_hello_world
+
+<div class="panel panel-info">
+**Note**
+{: .panel-heading}
+<div class="panel-body">
+
+
+
+
+```bash
+# scp hello wrold to all clients. sudo -u mpi for auto scp connect. see /home/mpi/.ssh 
+while read -r line; 
+ do 
+   sudo -u mpi scp /project/mpi_hello_world mpi@$line:/project/mpi_hello_world
+done < /project/hosts
+```
+ 
+</div>
+</div>