ena-dl has run its course, while it should still does what it says it does (haha at least at the time of writing this), it has been replaced by fastq-dl. fastq-dl has the same support as ena-dl but also includes the ability to download from SRA.
ena-dl, short for 'ENA download', is a tool for downloading FASTQ files from the European Nucleotide Archive. ENA was chosen over the Sequence Read Archive due to the availability of FASTQ files without the need for conversion (e.g. SRA format to FASTQ).
ena-dl takes an ENA/SRA accession (Study, Experiment, or Run) and queries ENA (via Data Warehouse API) to determine the Aspera/FTP FASTQ paths. These FASTQ files are then downloaded for each Run. For Samples or Experiments with multiple Runs, users can optionally merge the runs.
ena-dl was originally developed for Staphopia and is now being used for Bactopia, as you might imagine some of the functions are more geared towards these projects. There are currently no plans to add any other functions to ena-dl. Although don't let that stop you from using it, it still does what it says it does!
If you are looking for more rounded tools for downloading FASTQs, may I suggest enaBrowserTools or SRA Toolkit. These tools are built and maintained by EBI/NCBI and provide are more extensive access to their databases.
ena-dl is available from Bioconda and I highly recommend you go this route to for installation.
conda install -c conda-forge -c bioconda ena-dl
However, being a single Python script, with a single dependency, ena-dl is pretty straight forward to set up from source.
git clone git@github.com:rpetit3/ena-dl.git
cd ena-dl
pip3 install -r requirements.txt
python3 ena-dl.py
Feel free to drop it in your $PATH somewhere!
ena-dl requires a single ENA/SRA Study, Experiment, or Run accession and FASTQs for all Runs that fall under the given accession will be downloaded. For example, if a Study accession is given all Runs under that studies umbrella will be downloaded.
usage: ena-dl [-h] [--aspera STRING] [--aspera_key STRING]
[--aspera_speed STRING] [--is_study] [--is_experiment]
[--is_run] [--group_by_experiment] [--group_by_sample]
[--outdir OUTPUT_DIR] [--max_retry INT] [--ftp_only] [--silent]
[--debug] [--version]
ACCESSION
ena-dl - Download FASTQs from ENA
optional arguments:
-h, --help show this help message and exit
Required Options:
ACCESSION ENA accession to query. (Study, Experiment, or Run
accession)
Aspera Connect Options:
--aspera STRING Path to the Aspera Connect tool "ascp" (Default:
"which ascp")
--aspera_key STRING Path to Aspera Connect private key, if not given,
guess based on ascp path
--aspera_speed STRING
Speed at which Aspera Connect will download. (Default:
100M)
Query Related Options:
--is_study Query is a Study.
--is_experiment Query is an Experiment.
--is_run Query is a Run.
--group_by_experiment
Group Runs by experiment accession.
--group_by_sample Group Runs by sample accession.
Helpful Options:
--outdir OUTPUT_DIR Directory to output downloads to. (Default: ./)
--max_retry INT Maximum times to retry downloads (Default: 10)
--ftp_only FTP only downloads.
--silent Only critical errors will be printed.
--debug Skip downloads, print what will be downloaded.
--version show program's version number and exit
ena-dl.py PRJNA248678
The above command would download 3 runs that fall under Study PRJNA248678. The relationship of Study to Run is a 1-to-many relationship, or there can be many Run accessions associated with a single Study Accession. You could use --group_by_experiment to group these runs by Experiment accession (or --group_by_sample for Sample accession).
ena-dl.py SRX477044
The above command would download the single run that fall under Experiment SRX477044. The relationship of Experiment to Run is a 1-to-many relationship, or there can be many Run accessions associated with a single Experiment Accession (e.g. resequencing the same sample). Although in most cases, especially for bacterial samples, it is a 1-to-1 relationship. In any case, you can use --group_by_experiment to merge multiple runs associated with an Experiment accession into a single FASTQ file (or --group_by_sample for Sample accession).
ena-dl.py SRR1178105
The above command would download the Run SRR1178105. Run accessions are the end of the line (1-to-1 relationship)
Users can use Aspera Connect to speed up the download of FASTQs from ENA. Installation and setup of Aspera Connect is out of the scope of this documentation, but I can assure you its a simple installation.
ena-dl.py SRR1178105 --aspera /path/to/ascp
The above command will attempt to download SRR1178105 using the ascp tool. By default it will try to use the private key file that is included during the Aspera Connect installation. If it is not found you will need to use the --aspera_key parameter to specify its path.