EECS 280 Tutorials

CAEN Linux

This tutorial will show you how to copy source code from your Laptop to CAEN Linux. CAEN Linux is a server in a University data center that runs the Linux operating system. It’s useful for making sure that your code works on a computer that is a lot like the autograder.

Install

Everyone who registers for an EECS class (like EECS 280) should receive a CAEN account automatically by the first day class. If you register after the first day of class, you should get your account within 24 hours of registration.

ssh and rsync

Make sure you have ssh and rsync installed. Your versions might be different. They are installed by default on macOS and Windows/WSL users may have already followed these instructions.

$ ssh -V
OpenSSH_7.4p1, LibreSSL 2.5.0
$ rsync --version
rsync  version 2.6.9  protocol version 29

Duo Mobile

You should already have the Duo Mobile two factor authentication app installed and configured according the ITS documentation.

VPN

To access CAEN Linux from off campus, you’ll first need to connect to the UM VPN Service. Follow the ITS instructions.

Test log in

Test an SSH connection. Be sure to change awdeorio to your own uniqname.

$ ssh -T awdeorio@login.engin.umich.edu
The authenticity of host 'login.engin.umich.edu (141.213.74.65)' can't be established.
ECDSA key fingerprint is SHA256:LL0GPTtaVGa6gvv2kVpGq4ZULA1l5pw2wXC4dK3ymIk.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'login.engin.umich.edu,141.213.74.65' (ECDSA) to the list of known hosts.
Password: 
Duo two-factor login for awdeorio

Enter a passcode or select one of the following options:

 1. Duo Push to XXX-XXX-3142
 2. Phone call to XXX-XXX-3142
 3. SMS passcodes to XXX-XXX-3142

Passcode or option (1-3): 1
Success. Logging you in...
...
-bash-4.2$ 

Exit as soon as your test is successful.

$ exit
Connection to login.engin.umich.edu closed.

Copy with rsync

Next, we will copy our source code to CAEN Linux using the rsync command line program.

$ ls
main.cpp

Clean up first to avoid copying binary files.

$ make clean

Next, copy files using rsync. Remember to change awdeorio to your username.

$ rsync -rtv --exclude '.git*' ../p1-stats/ awdeorio@login.engin.umich.edu:p1-stats-copy/
building file list ... done
created directory p1-stats-copy
./
Makefile
main.cpp
main_test.in
main_test.out.correct
main_test_data.tsv
p1_library.cpp
p1_library.hpp
stats.cpp
stats.hpp
stats_public_test.cpp
stats_tests.cpp

sent 9557 bytes  received 268 bytes  19650.00 bytes/sec
total size is 8818  speedup is 0.90

Login with ssh

Now log in to CAEN Linux. Your terminal is now a shell on a different computer, caen-vnc-vm16 in this example. Yours may be different. Don’t forget to change awdeorio to your own uniqname.

$ ssh awdeorio@login.engin.umich.edu
$ hostname
caen-vnc-vm16.engin.umich.edu

Notice that the folder copied earlier.

$ ls
p1-stats-copy

Change directory into the copied folder and double-check that all binary files are cleaned up.

$ cd p1-stats-copy
$ make clean

Compile and run main.

$ make main.exe
$ ./main.exe
Hello world!

A good practice is to run a regression test on CAEN Linux. In EECS 280, that’s make test. Your results on CAEN Linux should match the Autograder and your own computer.

$ make test

Log out. Notice that after logging out, you are back to using a shell on your laptop.

$ exit
$ hostname
your-laptop-name

Avoiding repeated 2FA

CAEN requires two factor authentication (2FA) with every rsync copy or ssh login. Avoid repeated 2FA by configuring SSH to share a connection.

Add some lines to the SSH config file, which lives in ~/.ssh/config.

$ echo -e '# SSH multiplexing\nHost *\n  ControlMaster auto\n  ControlPersist yes\n   ControlPath ~/.ssh/socket-%C\n  ServerAliveInterval 60\n  ServerAliveCountMax 5' >> ~/.ssh/config
$ chmod 600 ~/.ssh/config

Check your ~/.ssh/config file.

$ cat ~/.ssh/config
# SSH multiplexing
Host *
  ControlMaster auto
  ControlPersist yes
  ControlPath ~/.ssh/socket-%C
  ServerAliveInterval 60
  ServerAliveCountMax 5

SSH into CAEN Linux.

$ ssh awdeorio@login.engin.umich.edu
Password:
Duo two-factor login for awdeorio

Enter a passcode or select one of the following options:

 1. Duo Push to XXX-XXX-3142
 2. Phone call to XXX-XXX-3142
 3. SMS passcodes to XXX-XXX-3142

Passcode or option (1-3): 1
Success. Logging you in...

$

Open a second terminal and run an rsync command, which uses the new configuration. No authentication is required!

$ rsync -rtv --exclude '.git*' ../p1-stats/ awdeorio@login.engin.umich.edu:p1-stats-copy/
building file list ... done

sent 273 bytes  received 20 bytes  586.00 bytes/sec
total size is 13015  speedup is 44.42

$ ls
main.cpp

Version control on CAEN Linux

An alternative to copying code to CAEN Linux is checking out a your code from GitHub.

SSH to a CAEN Linux machine and see the copy we made earlier using rsync.

$ ssh awdeorio@login.engin.umich.edu
$ ls
p1-stats-copy  # this is from our rsync'ed copy earlier

Notice that the copy is not under version control.

$ cd p1-stats-copy
$ git status
fatal: Not a git repository (or any of the parent directories): .git

Change directory and git clone your repo.

$ cd ~  # This will move to your home directory
$ git clone https://github.com/awdeorio/p1-stats.git
$ ls
p1-stats p1-stats-copy

Pro-tips

Synchronizing deleted files

Tell rsync to synchronize deleted files. In other words, if it’s gone on your laptop, delete it on CAEN.

$ rsync -rtv --delete --exclude '.git*' ../p1-stats/ awdeorio@login.engin.umich.edu:p1-stats-copy/

Don’t synchronize Git-ignored files

Tell rsync not to synchronize files ignored by Git. You can also combine this option with --delete.

$ rsync -rtv --exclude '.git*' --filter=':- .gitignore' ../p1-stats/ awdeorio@login.engin.umich.edu:p1-stats-copy/

make sync shortcut

Avoid typing a long rsync command by adding a Makefile target. Add these lines to the end of your Makefile. Notice that’s a TAB character before rsync.

# Copy files to CAEN Linux
sync :
	rsync \
  -rtv \
  --delete \
  --exclude '.git*' \
  --filter=':- .gitignore' \
  ../p1-stats/ \
  awdeorio@login.engin.umich.edu:p1-stats-copy/

Now you can type make sync as a short cut.

$ make sync
rsync \
  -rtv \
  --delete \
  --exclude '.git*' \
  --filter=':- .gitignore' \
  ../p1-stats/ \
  awdeorio@login.engin.umich.edu:p1-stats-copy/
building file list ... done
./
Makefile

sent 446 bytes  received 60 bytes  1012.00 bytes/sec
total size is 8939  speedup is 17.67

$ make sync
make: Nothing to be done for `sync'.

Acknowledgments

Original document written by Andrew DeOrio awdeorio@umich.edu.

This document is licensed under a Creative Commons Attribution-NonCommercial 4.0 License. You’re free to copy and share this document, but not to sell it. You may not share source code provided with this document.