Fetchngs Pipeline From nf-core

Fetchngs pipeline constitutes several built-in programs/scripts to retrieve metadata and raw FASTQ files from public and private databases such as SRA, ENA, DDBJ, GEO and Synapse. This pipeline is supported by nf-core

Installation

Fetchngs is built using Nextflow, a workflow tool to run tasks across multiple compute infrastructures and it also uses Docker/Singularity containers making installation trivial and results highly reproducible. This guide covers the installation and configuration for Ubuntu

Nextflow

a. Make sure that Java v8+ is installed

java -version

b. Install Nextflow

curl -fsSL get.nextflow.io | bash

c. Move the file to a directory accessible by your $PATH variable

sudo mv nextflow /usr/local/bin/

Docker

For more information, visit Docker website

a. Update the apt package index, and install the latest version of Docker Engine

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io

b. List the versions available in your repo

apt-cache madison docker-ce

c. Install a specific version

sudo apt-get install docker-ce=<VERSION_STRING> docker-ce-cli=<VERSION_STRING> containerd.io

d. Verify that Docker is installed correctly by running the hello-world image

sudo docker run hello-world

e. Enable Docker permissions

sudo chmod 666 /var/run/docker.sock

nf-core

a. Install nf-core tools

sudo pip3 install nf-core

b. List all nf-core pipelines and show available updates

nf-core list

Usage

To simplify the process, a scr/fetch-data.sh script provides a safe and efficient method for fetching data

bash fetch-data.sh -i IDs.txt -t sra -n rnaseq -o results -p 16 -m 250 -x n

Arguments

Mandatory

• -i: Identifiers provided in a txt file, one per line. These can be from SRA, ENA, DDBJ, GEO or Synapse repositories. An example is available in data

• -t: Specifies the type of identifier provided: sra, synapse

• -n: Samplesheet name for direct use with the nf-core/rna-seq pipeline will be created (CSV) rnaseq

• -o: The output directory where the results will be saved

Optional

• -p: CPUs

• -m: Max memory to be used

• -x: This execution is a resume of a previous run or it is a new run. The options are: y or n

Running in the background

The Nextflow -bg flag launches Nextflow in the background or alternatively, you can use screen/tmux or similar tool to create a detached session which you can log back into at a later time

Result

The script will create a local directory based on the given output name showing the following folders:

• output_name: Contains metadata and raw FASTQC files

• work: Contains the main pipeline workflows

• 20220113-001006.COMMAND: Contains the commands used for the actual launch. File name contains the date (%y%m%d) and the time (%H%M%S) when the command was last run.

Bug Reports

Please report bugs through the GitHub issues system