The SNP Pipeline software package consists of python scripts and shell scripts with dependencies on executable programs launched by the scripts.

Step 1 - Operating System Requirements

The SNP Pipeline runs in a Linux environment. It has been tested on the following platforms:

  • Red Hat
  • CentOS
  • Ubuntu

Step 2 - Executable Software Dependencies

You should have the following software installed before using the SNP Pipeline.

  • Bowtie2, a tool for aligning reads to long reference sequences
  • SMALT, a tool for aligning reads to long reference sequences
  • SAMtools, utilities for manipulating alignments in the SAM format
  • Picard, a set of tools for manipulating sequencing data in SAM/BAM/CRAM/VCF format
  • VarScan, a tool to detect variants in NGS data
  • tabix, a generic indexer for tab-delimited genome position files
  • bgzip, part of the tabix package, bgzip is a block compression utility
  • BcfTools, utilities for variant calling and manipulating VCFs and BCFs
  • fastq-dump, an SRA Toolkit utility for fetching samples from NCBI SRA

Note: you will need either Bowtie2 or SMALT. You do not have to install both. However, the included result files were generated with Bowtie2. Your results may differ when using SMALT.

Step 3 - Environment Variables

Define the CLASSPATH environment variable to specify the location of the Picard and VarScan jar files. Add the following lines (or something similiar) to your .bashrc file:

export CLASSPATH=~/software/picard/picard.jar:$CLASSPATH
export CLASSPATH=~/software/varscan.v2.3.9/VarScan.v2.3.9.jar:$CLASSPATH

Step 4 - Python

The SNP pipeline requires python version 2.6, 2.7, 3.3, 3.4, or 3.5. The pipeline has not been tested on other python versions. If you do not already have python installed, you should install version 2.7. You can either build from source or install a precompiled version with your Linux package manager.

Step 5 - Pip

This can be a troublesome installation step – proceed with caution. The pip tool is used to install python packages including the snp-pipeline and other packages used by the snp-pipeline. Some newer versions of Python include pip. Check to see if pip is already installed:

$ pip -V

If pip is not already installed, proceed as follows:

Download from
$ python --user

Note: avoid using sudo when installing pip. Some users have experienced problems installing and loading packages when pip is installed using sudo.

Step 6 - Python Package Dependencies

For the most part, the installer automatically installs the necessary python packages used by snp-pipeline. However, not all python packages can be reliably installed automatically. The packages listed below may need to be manually installed if automatic installation fails. You can either install these packages now, or hope for the best and manually install later if the automatic installation fails.

  • Biopython, a set of tools for biological computation written in Python.

Step 7 - Install the SNP Pipeline Python Package

There is more than one way to install the SNP Pipeline depending on whether you intend to work with the source code or just run it.

Installation Method 1 for Most Users

This is the recommended installation method for new users.

If you want to run the software without viewing or changing the source code, follow the instructions below.

At the command line:

$ pip install --user snp-pipeline

Update your .bashrc file with the path to user-installed python packages:

export PATH=~/.local/bin:$PATH

Or, if you have virtualenvwrapper installed:

$ mkvirtualenv snp-pipeline
$ pip install snp-pipeline

Installation Method 2 for Software Developers

If you intend to work with the source code in the role of a software developer, you should clone the GitHub repository as described in the Contributing section of this documentation.

Upgrading SNP Pipeline

If you previously installed with pip, you can upgrade to the newest version from the command line:

$ pip install --user --upgrade snp-pipeline

Uninstalling SNP Pipeline

If you installed with pip, you can uninstall from the command line:

$ pip uninstall snp-pipeline


There is a dependency on the python psutil package. Pip will attempt to install the psutil package automatically when installing snp-pipeline. If it fails with an error message about missing Python.h, you will need to manually install the python-dev package. In Ubuntu, use this command:

$ sudo apt-get install python-dev

You may need to upgrade your Java Runtime Environment (JRE) to run Picard.