The information can be taken from https://github.com/NIH-HPC/Singularity-Tutorial. I’m just documenting what I understand step-by-step

EXEC Command

Using the exec command, we can run commands within the container from the host system.

[user1@node ~]$ singularity exec lolcow_latest.sif cowsay 'How is today?'
 _______________
< How is today? >
 ---------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

RUN Command

Sometimes you can run a container

 [user1@node ~]$ singularity run lolcow_latest.sif
 _____________________________________
/ Fine day to work off excess energy. \
\ Steal something heavy.              /
 -------------------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

A special script “runscript” is activated when the “run” command is exercised. To have a closer look

[user1@node ~]$ singularity inspect --runscript lolcow_latest.sif
#!/bin/sh

    fortune | cowsay | lolcat

runscript consists of three simple commands with the output of each command piped to the subsequent command. Altenatively, you can do a

[user1@node ~]$ ./lolcow_latest.sif

Pipes and Redirection

Singularity allows piping services so that the host system can interact with the container. Here we are executing a command in the container and piping the output out into a file called output.txt

[user1@node ~]$ singularity exec lolcow_latest.sif cowsay moo > output.txt

You will notice that the output has been pushed to output.txt. Make sure you create output.txt prior

[user1@node ~]$ vim output.txt

Inside output.txt

 How are you >
 -------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Let’s say we create a file called HelloThere and put in a text called “Shame On You”. The command is then fed into cowsay.

% cat HelloThere | singularity exec lolcow_latest.sif cowsay -n
______________
< Shame on You >
 --------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

References:

1. https://github.com/NIH-HPC/Singularity-Tutorial

References

1. https://github.com/NIH-HPC/Singularity-Tutorial

The Official Documentation can be found at https://sylabs.io/guides/3.0/user-guide/installation.html

Prerequisites 1 – Yum

If you are using CentOS, you may want to put the necessary libraries and dependencies in first.

yum install -y && \
yum groupinstall -y 'Development Tools' && \
yum install -y \
openssl-devel \
libuuid-devel \
libseccomp-devel \
wget \
squashfs-tools

Prerequisites 2 – Go

Go to the Download Page https://go.dev/dl/ to download the Linux Version.

Extract the archive you downloaded into /usr/local, creating a Go tree in /usr/local/go.

This step below will remove a previous installation at /usr/local/go, if any, prior to extracting. Please back up any data before proceeding.

% rm -rf /usr/local/go && tar -C /usr/local -xzf go1.17.5.linux-amd64.tar.gz

Add /usr/local/go/bin to the PATH environment variable. You can do this by adding the following line to your $HOME/.profile or /etc/profile (for a system-wide installation):

export PATH=$PATH:/usr/local/go/bin

Verify the Installation with the command

% go version

Compiling Singularity

To download Singularity, do visit the download site. Singularity uses a build system called makeit. mconfig is called to generate Makefile and them make is used to compile and install

% cd singularity
% ./mconfig
 --prefix=/usr/local/singularity-ce-3.9.2
% cd build
% make
% make install

Source bash-completion file

To enjoy bash completion with Singularity commands and options, source the bash-completion file. you need to source the appropriate file and add it to the bash-completion directory in /etc so that it will be sourced automatically when you start another shell.

% . /usr/local/singularity-ce-3.9.2/etc/bash_completion.d/singularity
% cp /usr/local/singularity-ce-3.9.2/etc/bash_completion.d/singularity /etc/bash_completion.d/

Testing

As long as you see a cow your installation is working properly…….

singularity run library://godlovedc/funny/lolcow

/ Q: What is the difference between a \
\ duck? A: One leg is both the same.  /
 -------------------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

References

1. https://sylabs.io/guides/3.0/user-guide/installation.html
2. https://github.com/NIH-HPC/Singularity-Tutorial