Convert multiple sra files to fastq format

[caa5042]

Hi guys,

I am trying to write a for loop in the terminal (im on a mac) to convert several .sra files to fastq format.

SO this command works for just a single file:

./sratoolkit.2.3.2-5-mac-64/bin/fastq-dump ./SRR770514.sra

Now I'm trying to use a for loop to do the same thing for multiple files. This is what I have:

for fn in *.sra
do ./sratoolkit.2.3.2-5-mac-64/bin/fastq-dump ./"$fn".sra
done

but its not working...i've tried several variations..like "$fn.sra" and even tried without the quotes but nothing works..please help

[Richard Finney]

get rid of the ".sra" at the end of the command line in the middle of the for loop.

You can debug by just using ls instead of the fastqdump command ... like this ...

[caa5042]

hmm that didnt work either

and how do I debug using ls?

[Richard Finney]

Get this to work


for fn in *.sra
do ls -l ${fn}
done

[caa5042]

I think the terminal is just not responding to for loops...i dont get an error or anything either

any other ideas?

[Richard Finney]

What shell are you running?

type "echo $SHELL" at the command prompt.

The syntax I provided is "bash shell".

You can run bash by simply typing "bash" and hit return at the command line.

[caa5042]

it says /bin/bash when i run echo $SHELL

[GenoMax]

Have you tried providing full path to the SRA files in the for loop?

for fn in *.sra
do ./sratoolkit.2.3.2-5-mac-64/bin/fastq-dump /full_path_to/"$fn".sra
done

When you say it is not working what does that exact mean? Are you getting errors or nothing is happening.

[chadn737]

Try this, its what I use.

DIR="$1/*.sra"

for file in $DIR

do

/path/to/fastq-dump $file

done

[JamieHeather]

I feel like we've missed the easiest solution:

fastq-dump *

[caa5042]

Hi Jamie. You mean type the code just like that? with no loop or any of the other code?

[JamieHeather]

Just like that - works fine in bash anyway. If you have any files that aren't .sras in the directory you'll have to get a bit more specific, like so (with a little bit of tidying up after):

fastq-dump *.sra
rm *.sra

[genomeHunter]

If you have multiple cores, this could be even better:

find . -name *.sra | xargs -P $NUM_CORES -n 1 fastq-dump

My disk can easily handle 16 simultaneous dumps.

Cheers,
GH

[JamieHeather]

Just noticed that the solution I posted earlier doesn't work if you use the --split flag; when required I use this:

for i in *sra; do fastq-dump --split-3 $i; done

[ThePresident]

Originally Posted by JamieHeather

Just noticed that the solution I posted earlier doesn't work if you use the --split flag; when required I use this:

for i in *sra; do fastq-dump --split-3 $i; done

Saved my life man!

TP