Quick Start

This guide is intended for running SingularityCE on a computer where you have root (administrative) privileges, and will install SingularityCE from source code. Other installation options, including building an RPM package and installing SingularityCE without root privileges, are discussed in the installation section of the admin guide.

If you need to request an installation on your shared resource, see the section on requesting an installation for information to send to your system administrator.

For any additional help or support contact the Sylabs team: https://www.sylabs.io/contact/

Quick Installation Steps

You will need a Linux system to run SingularityCE natively. Options for using SingularityCE on Mac and Windows machines, along with alternate Linux installation options, are discussed in the installation section of the admin guide.

If you have an existing version of SingularityCE installed from source, which you wish to upgrade or remove / uninstall, see the installation section of the admin guide.


Install system dependencies

You must first install development tools and libraries to your host.

On Debian-based systems, including Ubuntu:

# Ensure repositories are up-to-date
sudo apt-get update
# Install debian packages for dependencies
sudo apt-get install -y \
   autoconf \
   automake \
   cryptsetup \
   git \
   libfuse-dev \
   libglib2.0-dev \
   libseccomp-dev \
   libtool \
   pkg-config \
   runc \
   squashfs-tools \
   squashfs-tools-ng \
   uidmap \
   wget \

On versions 8 or later of RHEL / Alma Linux / Rocky Linux, as well as on Fedora:

# Install basic tools for compiling
sudo dnf groupinstall -y 'Development Tools'
# Install RPM packages for dependencies
sudo dnf install -y \
   autoconf \
   automake \
   crun \
   cryptsetup \
   fuse3-devel \
   git \
   glib2-devel \
   libseccomp-devel \
   libtool \
   squashfs-tools \
   wget \

On SLES / openSUSE Leap:

# Install RPM packages for dependencies
sudo zypper in \
 autoconf \
 automake \
 cryptsetup \
 fuse3-devel \
 gcc \
 gcc-c++ \
 git \
 glib2-devel \
 libseccomp-devel \
 libtool \
 make \
 pkg-config \
 runc \
 squashfs \
 wget \

Install sqfstar / tar2sqfs for OCI-mode

If you intend to use the OCI mode of SingularityCE, your system must provide either:

  • squashfs-tools / squashfs >= 4.5, which provides the sqfstar utility. Note that older versions of these packages, provided by many distributions, do not include sqfstar.

  • squashfs-tools-ng, which provides the tar2sqfs utility. This is not packaged by all distributions.

Below are instructions on how to obtain one of these two utilities on various distributions.

Debian / Ubuntu

On Debian/Ubuntu squashfs-tools-ng is available in the distribution repositories. It has been included in the Install system dependencies step above. No further action is necessary.


On Fedora, the squashfs-tools package, included in the Install system dependencies step above, includes sqfstar. No further action is necessary.

RHEL / Alma Linux / Rocky Linux

On RHEL and derivatives, the squashfs-tools-ng package is now available in the EPEL repositories.

Follow the EPEL Quickstart for you distribution to enable the EPEL repository. Install squashfs-tools-ng with dnf.

sudo dnf install squashfs-tools-ng
SLES / openSUSE Leap

On SLES/openSUSE, follow the instructions at the filesystems project to obtain a more recent squashfs package, which provides sqfstar.

Next steps

You are now ready to install SingularityCE. There are 3 broad steps to installing SingularityCE itself:

  1. Installing Go

  2. Downloading SingularityCE

  3. Compiling SingularityCE Source Code

Install Go

SingularityCE is written in Go, and may require a newer version of Go than is available in the repositories of your distribution. We recommend installing the latest version of Go from the official binaries.

SingularityCE aims to maintain support for the two most recent stable versions of Go. This corresponds to the Go Release Maintenance Policy and Security Policy, ensuring critical bug fixes and security patches are available for all supported language versions.


If you have previously installed Go from a download, rather than an operating system package, it is important that you remove your go directory, e.g. rm -r /usr/local/go, before installing a newer version. Extracting a new version of Go over an existing installation can lead to errors when building Go programs, as it may leave behind old files, which have been removed or replaced in newer versions.

Visit the Go Downloads page and pick a package archive suitable to the environment you are in. Once the download is complete, extract the archive to /usr/local (or follow other instructions on the Go installation page). Alternatively, follow the commands here, making sure to replace specific values as needed:

$ export VERSION=1.21.0 OS=linux ARCH=amd64 && \
  wget https://dl.google.com/go/go$VERSION.$OS-$ARCH.tar.gz && \
  sudo tar -C /usr/local -xzvf go$VERSION.$OS-$ARCH.tar.gz && \
  rm go$VERSION.$OS-$ARCH.tar.gz

Set the Environment variable PATH to point to Go:

$ echo 'export PATH=/usr/local/go/bin:$PATH' >> ~/.bashrc && \
  source ~/.bashrc

Download SingularityCE from a release

You can download SingularityCE from one of the releases. To see a full list, visit the GitHub release page. After deciding on a release to install, you can run the following commands to proceed with the installation.

$ export VERSION=4.1.0 && \
    wget https://github.com/sylabs/singularity/releases/download/v${VERSION}/singularity-ce-${VERSION}.tar.gz && \
    tar -xzf singularity-ce-${VERSION}.tar.gz && \
    cd singularity-ce-${VERSION}


Do not attempt to build SingularityCE from the Source code (zip) or Source code (tar.gz) archives that are auto-generated by GitHub. These do not include some of the required internal dependencies needed to build SingularityCE. Instead, to build SingularityCE from source, use the archive named singularity-ce-${VERSION}.tar.gz.

Compile the SingularityCE source code

Now you are ready to build SingularityCE. Internal dependencies will be automatically downloaded. You can build SingularityCE using the following commands:

$ ./mconfig && \
    make -C builddir && \
    sudo make -C builddir install


SingularityCE must be installed as root to function properly.

Overview of the SingularityCE Interface

SingularityCE’s command line interface allows you to build and interact with containers transparently. You can run programs inside a container as if they were running on your host system. You can easily redirect I/O, use pipes, pass arguments, and access files, sockets, and ports on the host system from within a container.

The help command gives an overview of SingularityCE options and subcommands as follows:

$ singularity help

Linux container platform optimized for High Performance Computing (HPC) and
Enterprise Performance Computing (EPC)

  singularity [global options...]

  Singularity containers provide an application virtualization layer enabling
  mobility of compute via both application and environment portability. With
  Singularity one is capable of building a root file system that runs on any
  other Linux system where Singularity is installed.

  -c, --config string   specify a configuration file (for root or
                        unprivileged installation only) (default
  -d, --debug           print debugging information (highest verbosity)
  -h, --help            help for singularity
      --nocolor         print without color output (default False)
  -q, --quiet           suppress normal output
  -s, --silent          only print errors
  -v, --verbose         print additional information
      --version         version for singularity

Available Commands:
  build       Build a Singularity image
  cache       Manage the local cache
  capability  Manage Linux capabilities for users and groups
  completion  Generate the autocompletion script for the specified shell
  config      Manage various singularity configuration (root user only)
  delete      Deletes requested image from the library
  exec        Run a command within a container
  help        Help about any command
  inspect     Show metadata for an image
  instance    Manage containers running as services
  key         Manage OpenPGP keys
  keyserver   Manage singularity keyservers
  oci         Manage OCI containers
  overlay     Manage an EXT3 writable overlay image
  plugin      Manage Singularity plugins
  pull        Pull an image from a URI
  push        Upload image to the provided URI
  registry    Manage authentication to OCI/Docker registries
  remote      Manage singularity remote endpoints
  run         Run the user-defined default command within a container
  run-help    Show the user-defined help for an image
  search      Search a Container Library for images
  shell       Run a shell within a container
  sif         Manipulate Singularity Image Format (SIF) images
  sign        Add digital signature(s) to an image
  test        Run the user-defined tests within a container
  verify      Verify digital signature(s) within an image
  version     Show the version for Singularity

  $ singularity help <command> [<subcommand>]
  $ singularity help build
  $ singularity help instance start

For additional help or support, please visit https://www.sylabs.io/docs/

Information about individual subcommands can also be viewed by using the help command:

$ singularity help verify
Verify digital signature(s) within an image

  singularity verify [verify options...] <image path>

  The verify command allows a user to verify one or more digital signatures
  within a SIF image.

  Key material can be provided via PEM-encoded file, or via the PGP keyring. To
  manage the PGP keyring, see 'singularity help key'.

  -a, --all                                verify all objects
      --certificate string                 path to the certificate
      --certificate-intermediates string   path to pool of intermediate
      --certificate-roots string           path to pool of root certificates
  -g, --group-id uint32                    verify objects with the
                                           specified group ID
  -h, --help                               help for verify
  -j, --json                               output json
      --key string                         path to the public key file
      --legacy-insecure                    enable verification of
                                           (insecure) legacy signatures
  -l, --local                              only verify with local key(s)
                                           in keyring
      --ocsp-verify                        enable online revocation check
                                           for certificates
  -i, --sif-id uint32                      verify object with the specified ID
  -u, --url string                         specify a URL for a key server

  Verify with a public key:
  $ singularity verify --key public.pem container.sif

  Verify with PGP:
  $ singularity verify container.sif

For additional help or support, please visit https://www.sylabs.io/docs/

SingularityCE uses positional syntax (i.e., the order of commands and options matters). Global options affecting the behavior of all commands follow immediately after the main singularity command. Then come subcommands, followed by their options and arguments.

For example, to pass the --debug option to the main singularity command and run SingularityCE with debugging messages on:

$ singularity --debug run library://lolcow

To pass the --containall option to the run command and run a SingularityCE image in an isolated manner:

$ singularity run --containall library://lolcow

SingularityCE 2.4 introduced the concept of command groups. For instance, to list Linux capabilities for a particular user, you would use the list command in the capability command group, as follows:

$ singularity capability list myuser

Container authors might also write help docs specific to a container, or for an internal module called an “app”. If those help docs exist for a particular container, you can view them as follows:

$ singularity inspect --helpfile container.sif  # See the container's help, if provided

$ singularity inspect --helpfile --app=foo foo.sif  # See the help for the app foo, if provided

Download pre-built images

You can use the search command to locate groups, collections, and containers of interest on the Container Library .

$ singularity search tensorflow
Found 22 container images for amd64 matching "tensorflow":

            Current software: tensorflow2; py3.7; r; jupyterlab1.2.6
            Signed by: 1B8565093D80FA393BC2BD73EA4711C01D881FCB








            Signed by: D0E30822F7F4B229B1454388597B8AFA69C8EE9F


You can use the pull and build commands to download pre-built images from an external resource like the Container Library or Docker Hub.

Using the pull subcommand

When called on a native SingularityCE image like those provided by the Container Library, pull simply downloads the image file to your system:

$ singularity pull library://lolcow

You can also use pull with a docker:// URI to reference Docker images served from a registry. In this case, pull does not just download an image file. Docker images are stored in layers, so pull must also combine those layers into a usable SingularityCE file.

$ singularity pull docker://sylabsio/lolcow

Pulling docker images may reduce reproducibility: if you were to pull a Docker image today and then wait six months and pull it again, you are not guaranteed to get the same image from docker on both occasions. If any of the source layers of the docker image has changed, the image will be altered. You can get around this by pulling docker images by digest, as follows:

$ singularity pull docker://alpine@sha256:69665d02cb32192e52e07644d76bc6f25abeb5410edc1c7a81a10ba3f0efb90a


SingularityCE will make a SIF image out of the underlying docker image; and because SIF images contain metadata (including timestamps), resulting SingularityCE images will not be bit-for-bit identical, even if they are created from docker images that were pulled by digest.

If reproducibility is a priority for you, the best option is to always build your images from the Container Library if possible.

Using the build subcommand

You can also use the build command to download pre-built images from an external resource. When using build you must specify a name for your container like so:

$ singularity build ubuntu.sif library://ubuntu

$ singularity build lolcow.sif docker://sylabsio/lolcow

Unlike pull, build will convert your image to the latest SingularityCE image format after downloading it. build is like a “Swiss Army knife” for container creation. In addition to downloading images, you can use build to create images from other images, or from scratch using a definition file. You can also use build to convert an image between the container formats supported by SingularityCE. To see a comparison of the SingularityCE definition file with Dockerfile, please see: this section.

Interacting with images

You can interact with images in several ways, each of which can accept image URIs in addition to local image paths.

As an example, the following command will pull a lolcow_latest.sif image from the Container Library:

$ singularity pull library://lolcow


The shell command allows you to spawn a new shell within your container and interact with it as though it were a virtual machine.

$ singularity shell lolcow_latest.sif

The change in prompt indicates that you have entered the container (though you should not rely on prompt forms to determine whether you are in a container or not).

Once inside of a SingularityCE container, you are the same user as you are on the host system.

Singularity> whoami

Singularity> id
uid=1000(david) gid=1000(david) groups=1000(david),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),116(lpadmin),126(sambashare)

shell also works with the library://, docker://, and shub:// URIs. This creates an ephemeral container that disappears when the shell is exited.

$ singularity shell library://lolcow

Executing Commands

The exec command allows you to execute a custom command within a container by specifying the image file. For instance, to execute the cowsay program within the lolcow_latest.sif container:

$ singularity exec lolcow_latest.sif cowsay moo
< moo >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

exec also works with the library://, docker://, and shub:// URIs. This creates an ephemeral container that executes a command and disappears.

$ singularity exec library://lolcow cowsay 'Fresh from the library!'
< Fresh from the library! >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Running a container

SingularityCE containers contain runscripts. These are user-defined scripts that define the actions a container should perform when someone runs it. The runscript can be triggered with the run command, or simply by calling the container as though it were an executable.

$ singularity run lolcow_latest.sif
< Mon Aug 16 13:01:55 CDT 2021 >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

$ ./lolcow_latest.sif
< Mon Aug 16 13:12:50 CDT 2021 >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

run also works with the library://, docker://, and shub:// URIs. This creates an ephemeral container that runs and then disappears.

$ singularity run library://lolcow
< Mon Aug 16 13:12:33 CDT 2021 >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Arguments to run

You can pass arguments to the runscript of a container. For example, the default runscript of the library://alpine container passes any arguments to a shell. We can ask the container to run echo command in this shell as follows:

$ singularity run library://alpine echo "hello"

Because SingularityCE runscripts are evaluated shell scripts, arguments can behave slightly differently than in Docker/OCI runtimes, in the event that they contain expressions that have special meaning to the shell. Here is an illustrative example:

$ docker run -it --rm alpine echo "\$HOSTNAME"

$ singularity run docker://alpine echo "\$HOSTNAME"

$ singularity run docker://alpine echo "\\\$HOSTNAME"

To replicate Docker/OCI behavior, you may need additional escaping or quoting of arguments.

Unlike the run command, the exec command does behave in the same manner as Docker/OCI, because it calls the specified executable directly:

$ singularity exec docker://alpine echo "\$HOSTNAME"

$ singularity exec docker://alpine echo "\\\$HOSTNAME"

Working with Files

Files on the host are reachable from within the container:

$ echo "Hello from inside the container" > $HOME/hostfile.txt

$ singularity exec lolcow_latest.sif cat $HOME/hostfile.txt
Hello from inside the container

This example works because hostfile.txt exists in the user’s home directory ($HOME). By default, SingularityCE bind mounts $HOME, the current working directory, and additional system locations from the host into the container.

You can specify additional directories to bind mount into your container with the --bind option. In the following example, the data directory on the host system is bind mounted to the /mnt directory inside the container.

$ echo "Drink milk (and never eat hamburgers)." > /data/cow_advice.txt

$ singularity exec --bind /data:/mnt lolcow_latest.sif cat /mnt/cow_advice.txt
Drink milk (and never eat hamburgers).

Pipes and redirects also work with SingularityCE commands, just like they do with normal Linux commands:

$ echo "Drink milk (and never eat hamburgers)." | singularity exec lolcow_latest.sif cowsay
< Drink milk (and never eat hamburgers). >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Building images from scratch

SingularityCE versions 3.0 and above produce immutable images in the Singularity Image File (SIF) format. This ensures reproducible and verifiable images, and allows for many extra benefits such as the ability to sign and verify your containers.

However, during testing and debugging, you may want an image format that is writable. This way you can shell into the image and install software and dependencies until you are satisfied that your container will fulfill your needs. For these scenarios, SingularityCE also supports the sandbox format (which is really just a directory).

Sandbox Directories

To build into a sandbox (container in a directory) use the build --sandbox command and option:

$ singularity build --sandbox ubuntu/ library://ubuntu

This command creates a sub-directory called ubuntu/ with an entire Ubuntu operating system and some SingularityCE metadata in your current working directory.

You can use commands like shell, exec , and run with this directory just as you would with a SingularityCE image. If you pass the --writable option when you use your container, you can also write files within the sandbox directory (provided you have the permissions to do so).

$ singularity exec --writable ubuntu touch /foo

$ singularity exec ubuntu/ ls /foo

Converting images from one format to another

The build command allows you to build a new container from an existing container. This means that you can use it to convert a container from one format to another. For instance, if you have already created a sandbox (directory) and want to convert it to the Singularity Image Format, you can do so as follows:

$ singularity build new.sif sandbox

Note, however, that this approach may break reproducibility, in the event that you have altered your sandbox outside of the context of a definition file, so you are advised to exercise care.

SingularityCE Definition Files

For a reproducible, verifiable and production-quality container, it is recommended that you build your SIF file using a SingularityCE definition file. This also makes it easy to add files, environment variables, and install custom software, while still starting from your base of choice (e.g., the Container Library).

A definition file has a header and a body. The header determines the base container to begin with, and the body is further divided into sections that perform tasks such as software installation, environment setup, and copying files into the container from host system.

Here is an example of a definition file:

BootStrap: library
From: ubuntu:22.04

   apt-get -y update
   apt-get -y install cowsay lolcat

   export LC_ALL=C
   export PATH=/usr/games:$PATH

   date | cowsay | lolcat

   Author Sylabs

To build a container from this definition file (assuming it is a file named lolcow.def), you would call build as follows:

$ sudo singularity build lolcow.sif lolcow.def

In this example, the header tells SingularityCE to use a base Ubuntu 22.04 image from the Container Library. The other sections in this definition file are as follows:

  • The %post section is executed within the container at build time, after the base OS has been installed. The %post section is therefore the place to perform installations of new libraries and applications.

  • The %environment section defines environment variables that will be available to the container at runtime.

  • The %runscript section defines actions for the container to take when it is executed. (These commands will therefore not be run at build time.)

  • And finally, the %labels section allows for custom metadata to be added to the container.

This is a very small example of the things that you can do with a definition file. In addition to building a container from the Container Library, you can start with base images from Docker Hub and use images directly from official repositories such as Ubuntu, Debian, CentOS, Arch, and BusyBox. You can also use an existing container on your host system as a base. Definition files also support “templating”: the ability to pass values from the command-line, or from a definitions file, that will replace placeholders in the definition file at build time.

If you want to build SingularityCE images but you don’t have administrative (root) access on your build system, you can build images using the Remote Builder.

This quickstart document just scratches the surface of all of the things you can do with SingularityCE!

If you need additional help or support, contact the Sylabs team: https://www.sylabs.io/contact/

SingularityCE on a shared resource

Perhaps you are a user who wants a few talking points and background to share with your administrator. Or maybe you are an administrator who needs to decide whether to install SingularityCE.

This document and the accompanying administrator documentation provide answers to many common questions.

If you need to request an installation from your administrator, you may decide to draft a message similar to this:

Dear shared resource administrator,

We are interested in having SingularityCE (https://www.sylabs.io/docs/)
installed on our shared resource. SingularityCE containers will allow us to
build encapsulated environments, meaning that our work is reproducible and
we are empowered to choose all dependencies including libraries, operating
system, and custom software. SingularityCE is already in use on many of the
top HPC centers around the world. Examples include:

    Texas Advanced Computing Center
    GSI Helmholtz Center for Heavy Ion Research
    Oak Ridge Leadership Computing Facility
    Purdue University
    National Institutes of Health HPC
    UFIT Research Computing at the University of Florida
    San Diego Supercomputing Center
    Lawrence Berkeley National Laboratory
    University of Chicago
    McGill HPC Centre/Calcul Québec
    Barcelona Supercomputing Center
    Sandia National Lab
    Argonne National Lab

Importantly, it has a vibrant team of developers, scientists, and HPC
administrators that invest heavily in the security and development of the
software, and are quick to respond to the needs of the community. To help
learn more about SingularityCE, I thought these items might be of interest:

    - Security: A discussion of security concerns is discussed at

    - Installation:

If you have questions about any of the above, you can contact the open
source list (https://groups.google.com/g/singularity-ce), join the open
source slack channel (singularityce.slack.com), or contact the organization
that supports SingularityCE directly (sylabs.io/contact). I can do my best
to facilitate this interaction if help is needed.

Thank you kindly for considering this request!