Using Penn Medicine Academic Computing Services (PMACS)

Table of contents

  1. Obtaining PMACS LPC Access
  2. Logging in to PMACS LPC
  3. Submitting tickets
  4. Making a project directory
  5. Loading modules and accessing module software
  6. Requesting software installations
  7. Installing Flywheel on your PMACS account
  8. Cloning and Updating GitHub Repos on PMACS
  9. Mounting a PMACS project directory on your local machine
  10. Enabling X11 forwarding
  11. Transferring files to and from the LPC
  12. Viewing niftis
  13. Using the batch system
  14. Stop receiving e-mails for each job you submit via bsub
  15. Running MATLAB on PMACS
  16. Running RStudio on PMACS
    1. X11
    2. Port Forwarding with Singularity
  17. Running data processing pipelines on PMACS
    1. Creating singularity images from dockerhub on PMACS
    2. Running the container on PMACS

This section gives an overview of how to get started on PMACS Limited Performance Computing (LPC) cluster. For additional information, check out the LPC wiki. NOTE: The full URL to the pmacs servers have not been included here. If you need to know the full URL, please ask on slack.

Obtaining PMACS LPC Access

Send the lab’s access manager (you can ask who this is on the #informatics Slack channel) your Pennkey, full name, and Penn email, and have them fill a ticket and request access for you. When access has been granted, you will receive an email with a temporary password through SecureShare. Log in via this link with your temporary password and set a new PMACS password. Your Pennkey and new PMACS password will be used to ssh into the LPC and to access the PMACS help desk/ticketing system.

Logging in to PMACS LPC

Once you’ve set up your login credentials for the PMACS LPC, you can SSH into the LPC from anywhere (even without Penn VPN). You can SSH into PMACS using the following command:

$ ssh -Y [username] #SSH only. No sftp. No outbound access. Can submit or check jobs.

Enter PMACS password when prompted.

You can submit jobs on bblsub, and you get interface with the outside world (e.g., using conda / pip install, wget).

In general, there is a set of software libraries and tools we expect you’ll need, such as R, conda, and FSL; we’ve made these available for you in a module. To load this module, simply type the following:

$ xbash
$ source /project/bbl_projects/apps/

You can also add the source line to your bash profile (add the line in the file ~/.bash_profile) so that it loads automatically every time you sign in.

Submitting tickets

Log in to the PMACS Help Desk with PMACS credentials. Under “Quick Actions” click “Need help? Report it.” Submit ticket under appropriate category.

Making a project directory

New project directories must be created for you by PMACS LPC admin. To have a new project directory created, you need to submit a ticket. Log into the PMACS Help Desk with PMACS credentials, and submit a “Systems” ticket specifying the desired project folder name (e.g. grmpy_diffusion) and who should have read access and read/write access to the folder (e.g. bbllpc). Once made, project directories can be found in project/ (e.g. /project/grmpy_diffusion).

Loading modules and accessing module software

Environment modules are used to load and unload available software (e.g. ANTs, mrtrix, R, ITK, dcm2niix, fsl, freesurfer, etc.). Hence, in order to use most software/applications that are available on PMACS, you must first load the appropriate module. To check which modules are available on PMACS, type module avail. To load a desired module, use module load [modulename]. Finally, to see what modules you have loaded, use module list.

For example, if I want to load python:

$ module load python # automatically loads latest version
$ python
$ exit()

Modules can be loaded and unloaded both in the log in node and in an interactive shell. You can access interactive shells via ibash (standard) or xbash (used for graphics, X11 forwarding enabled). In order to use some module software, however, you must be in an interactive shell!

For example:

$ module load mrtrix3/current
$ mrstats

will return -bash: mrstats: command not found


$ ibash
$ mrstats

will now reveal help documentation for mrstats.

In what circumstances do you use ibash you ask? From the LPC wiki:

“Use the interactive shell to:

  • Prepare you submit scripts
  • Find apps, browse appl
  • Work on anything you don’t have access to on the submit host
  • Browse /project/group directory
  • Prototype code and test apps”

Requesting software installations

Open source free apps and most imaging software needs to be installed by PMACS admin. This means you can’t install R, Stata, or Python packages on your own. You can submit a “Systems” ticket at PMACS Help Desk requesting that new software be installed.

Installing Flywheel on your PMACS account

You can install the Flywheel command line interface (CLI) locally, which is helpful as the CLI version updates frequently. Follow these steps to install the Flywheel CLI and gain access to fw commands. Complete these steps on the log in node, not in an interactive shell.

  1. Install miniconda in your home directory (/home/[pmacs username]):
    $ wget
    $ bash ./ -b -p $HOME/software/pkg/miniconda3
  2. Load miniconda
    $ source $HOME/software/pkg/miniconda3/bin/activate # should be whatever folder miniconda3/bin/activate is in
  3. Create flywheel python environment and activate it
    $ conda create -n flywheel anaconda python=3
    $ conda activate flywheel
  4. Install flywheel-sdk
    $ pip install flywheel-sdk
  5. Install flywheel-cli
    $ wget
    $ unzip
  6. The fw executable should be in the linux_amd64 folder. Add this directory to your path so that the fw command is accessible from all locations
    $ echo "export PATH=\$PATH:~/linux_amd64" >> ~/.bashrc
  7. Log in to flywheel using your API key (obtained from your Flywheel User Profile)
    $ fw login$APIkey
    $ fw status
    $ You are currently logged in as <username> to

Note: Sometimes fw status gets you this error message: 'Connection to timed out. (connect timeout=10)')': /api/auth/status. In this case, logging out of PMACS and logging in again should fix the issue.

Cloning and Updating GitHub Repos on PMACS

If you have already created an ssh private key for your PMACS account and have added it to both the ssh-agent on PMACS (~/.ssh/id_rsa and files) and to your GitHub account, you can clone, pull, and push git repositories using bblsub and an available github module on PMACS.

Specifically, to clone and update reposm you should first ssh in via bblsub

$ ssh -Y [username]@bblsub

Next, load a git-related module.

$ module load git/2.5.0 #or git-lfs/2.2.1

You can now use github as you normally would.

If you have not yet set up your PMACS ssh key, follow these instructions. You will only need to do this once.

  1. Generate a new ssh key using your github-associated email.
    $ ssh-keygen -t rsa -b 4096 -C "{}"
    • When promted to “Enter a file in which to save the key,” press Enter. This accepts the default file location.
    • When promted, enter a secure passphrase.
  2. Add your ssh key to the ssh-agent
    $ eval "$(ssh-agent -s)"
    $ ssh-add ~/.ssh/id_rsa
  3. Add your ssh key to your GitHub account.
    • Sign in to GitHub
    • Click on your profile photo and click Settings
    • Click SSH and GPG keys in the Settings sidebar
    • Click New SSH Key. “Title”: enter a relevant title for the new key (e.g. PMACS account). “Key”: copy the text in your ~/.ssh/ file (which should start with ssh-rsa and end with your email) and paste it into the Key text box. Click Add SSH Key.

Mounting a PMACS project directory on your local machine

  1. If you are using a Mac, first install OSXFuse and SSHFS.

  2. Make an empty mount point folder on your local machine. Make sure that only the user (not group or others) have access to this mount directory!
    $ mkdir /Users/<username>/ImageData/PMACS_remote
    $ chmod 700 /Users/<username>/ImageData/PMACS_remote
  3. Mount the desired PMACS directory to your newly created, local mount directory using sshfs and bblsub
    $ sshfs [username]@bblsub:<my-folder-on-PMACS> <my-local-mount-folder> -o defer_permissions,volname=project
  4. Unmount when done! You should run this unmount command from outside of the mount point.
    $ diskutil umount force /Users/<username>/ImageData/PMACS_remote

Enabling X11 forwarding

To use graphics on PMACS, make sure that you:

  • Have XQuartz installed on your local Mac
  • log in to bblsub via ssh -Y
  • use xbash for your interactive shell

Transferring files to and from the LPC

  • You can transfer files to and from PMACS with username@transfer. This can be used with SFTP, rsync, and scp. (You cannot use transfer for ssh).
  • bblsub can be used with scp, but transfer is reccomended. As in:
    $ [<username>@<source_server> ~]$ scp /data/jux/BBL/projects/multishell_diffusion/processedData/multishellPipelineFall2017/*/*/prestats/eddy/*_msRD.nii.gz <username>@transfer:/project/grmpy_diffusion/diffusion_metrics/
  • Transferring from cluster-to-cluster instead of through your local machine will run orders of magnitude faster. This is particularly true if you happen to be in the midst of a global pandemic and are relying on your home wifi.
  • Make sure you have full permissions for the destination you are writing to.

Viewing niftis

  • In order to use flseyes or afni to view images on a mac, in your local terminal, type:
    $ defaults write org.macosforge.xquartz.X11 enable_iglx -bool true
  • Restart your mac and then ssh onto PMACS, you should now be able to view images

Using the batch system

PMACS uses IBM’s Load Sharing Facility (LSF) to submit and monitor jobs. This is very different from SGE used on CUBIC. The biggest differences are you will use bsub to submit jobs and bjobs to monitor jobs instead of SGE’s qsub to submit jobs and qstat to monitor jobs.

The documentation for LSF can be found here.

Stop receiving e-mails for each job you submit via bsub

By default, every time you submit a job on PMACS using bsub, you will get an e-mail with what would normally be in a log file. To suppress this behavior, use the -o flag to specify the path to the log file.

$ bsub -o ~/jobinfo.log ~/

Alternatively, or in addition, you can add the following line to your .bashrc.

$ echo LSB_JOB_REPORT_MAIL=N >> ~/.bashrc


To run a MATLAB script on PMACS, simply do the following:

  1. Compose your script, for example:
    runALE # main command to be executed

    and save it, for instance as runexperimental1.m

  2. Compose a bash script to launch MATLAB, like so:
  module load matlab/2018b # load matlab
  matlab  -nodisplay -nosplash  -r /path/to/scripts/runexperimental1 # note, there's no file extension (.m)

and save it too:

  1. Submit the bash script as a job with bsub
   bsub -q matlab_normal  /path/to/scripts/

To run an interactive session:

  1. Run bsub -Is -XF -q matlab_interactive 'bash' from the initial login node.

  2. Type matlab to open Matlab using X11, or matlab -nodisplay to run the session in the terminal.

Running RStudio on PMACS

We have two ways of accessing RStudio on PMACS. It’s not installed by default in modules, but there are ways to scratch that itch for R users.


This is how to access RStudio with the least setup, but it suffers from the same issues all other X11 solutions have – poor graphic quality. Nevertheless, the process is simple:

  1. Temporarily source the central default modules if it is not in your bash profile
       $ source  /project/bbl_projects/apps/
  2. Activate rstudio enviroment
    $ conda activate rstudio
  3. Get into interactive mode.
    $  xbash
  4. Launch rstudio
    $ rstudio
  5. Optional. if you want to use other version of R , for instance R/3.6.3. Load the module of that R and set rstudio to use that R before lunching the rstudio.
    $  module load R/3.6.3
    $  export RSTUDIO_WHICH_R=/appl/R-3.6.3/bin/R

Port Forwarding with Singularity

This method leverages the rocker project’s awesome method of running RStudio in a container and forwarding the graphics over SSH. The project is built in Docker, but most HPCs tend to avoid using Docker for security purposes, and instead vouch for Singularity, which works quite the same way. This setup is admittedly slightly complicated, but if you want a true RStudio experience when doing data science, the results can’t be beat.


  • Real RStudio interface with no lag
  • Graphics load instantly
  • Computation is right where you need it


  • Complexity
  • We’re still figuring out how to set memory limits and how this will work with parallelised processes

Ok, let’s get to the steps. The following sources helped me put together this workflow: 1, 2, 3

First, pick a port number. RStudio by default tries to set it at 8787, so it’s safe to assume whenever you’re on the cluster that someone is already using it. Also, it’s a good idea to use 3 separate terminals to supervise what you’re doing. Let’s call them t1, t2, t3.

  1. Log in to bblsub on t1.
# In this example I'm using 9999. DO NOT USE THIS. BIG SAD.
t1[localmachine]$ ssh -Y -L localhost:9999:localhost:9999 <username>@bblsub
  1. From bblsub, login to the Singularity node on PMACS.
t1[<username>@bblsub ~]$ ssh singularity01
  1. On the Singularity node, fetch and set up the Singularity image.
# pull the docker image for tidyverse into singularity
t1[<username>@singularity01 ~]$ singularity pull --name rstudio.simg docker://rocker/tidyverse:latest

# convert this to a "sandboxed" writable image; you can hit "y" at the prompt to overwrite or change the name in the call
t1[<username>@singularity01 ~]$ singularity build --sandbox rstudio.simg rstudio.simg
  1. Launch the Singularity container and run RStudio (remember to specify a unique port).
# use the ampersand to run in the background, or else you won't be able to do anything on this terminal until you quit singularity

t1[<username>@singularity01 ~]$ singularity exec --writable rstudio.simg rserver --www-address= --www-port 9999 &

# you can find out what ports are currently in use with this command
t1[<username>@singularity01 ~]$ netstat -tunlp

# check for any rstudios
t1[<username>@singularity01 ~]$ netstat -tunlp | grep rserver
  1. On t2, login to bblsub and “listen” to the port from Singularity.
# I tend to just repeat the port numbers because I forget which is which
t2[localmachine]$ ssh -Y <username>@bblsub
t2[<username>@bblsub ~]$ ssh -NfL localhost:9999:localhost:9999 singularity01
  1. On t3, “listen” to the port from bblsub.
t3[localmachine ~]$ ssh -NfL localhost:9999:localhost:9999 singularity01
  1. Open RStudio in your browser.

Visit localhost:9999 in Chrome or Firefox.

You should now be in an RStudio GUI with access to any directory you want. The R installation is within the folder called rstudio.simg (it’s a Singularity image that we converted into a directory in step 3), so you are able to manage your own packages in there. If need be, you could do this setup multiple times and have RStudio images for each project directory on PMACS.

  1. Close each process you’re running.

When you’re done, use RStudio to close this safely – hit the orange button in the top right corner. This may shutdown the rserver process, but not the singularity exec you called in t1. Go to t1 and kill this manually:

t1[<username>@singularity01 projects]$ ps - x
47110 ?        S      0:00 sshd: <username>@pts/0
47111 pts/0    Ss     0:00 -bash
48226 pts/0    Sl     0:00 Singularity runtime parent
48242 pts/0    Sl     0:01 rserver --www-address=
49089 pts/0    R+     0:00 ps -x
t1[<username>@singularity01 projects]$ kill 48242 && kill 48226

Likewise, make sure you kill your port forwarding commands in t2 and t3. When you come back to continue working, loop back to step 4.

Running data processing pipelines on PMACS

Data processing pipelines, such as fmriprep and qsiprep, can be run easily by creating singularity images on PMACS. Below steps use qsiprep as an example, but they can be applied to other pipelines as well.

Creating singularity images from dockerhub on PMACS

  1. Log onto bblsub
    $ ssh -Y <user>@bblsub
  2. Connect to singularity
    $ ssh singularity01
  3. Pull the singularity image to PMACS and exit
    $ singularity pull docker://pennbbl/qsiprep:0.12.2
    $ exit
  4. Move the qsiprep image (in this case qsiprep_0.12.2.sif) to an images directory in your project directory

Running the container on PMACS

Before running the qsiprep container on PMACS, first get a freesurfer license. The license is necessary to run qsiprep without any error. Save the license also in the images directory and run the following command:

$ singularity run --cleanenv -B </path/to/project/directory>/data:/home/<user>/data,\
$ </path/to/project/directory>/images/license.txt:/appl/freesurfer-6.0.0/license.txt,\
$ </path/to/output/directory>:/home/<user>/<output directory name> \
$ </path/to/project/directory>/images/qsiprep_0.12.2.sif \
$ --fs-license-file /appl/freesurfer-6.0.0/license.txt \
$ --work-dir </path/to/working/directory> \
$ --output-resolution <value> \
$ </path/to/project/directory>/data \
$ </path/to/output/directory> \
$ participant

There are several parts to this command:

  • –cleanenv option means that we don’t want to pass the host environment to the container (visit Environment and Metadata for more)
  • -B is an argument to bind paths; simply put, </path/to/project/directory>/data will be called as */home//data* in the container (visit [Bind Paths]( for more)
  • –output-resolution specifies the isotropic voxel size in mm the data will be resample to after preprocessing (for more information on the arguments see qsiprep documentation)