pipe two inputs to a command (coverageBed)

[hari_iyer16]

Hi,
I am trying to run coverageBed on my data. Since it is huge, I have to split the data into each chromosome and run them separately. coverageBed takes two input files, the data.bed file (contains the sequencing data) and the windows.bed (a file with defined windows in which the sequencing coverage has to be estimated). I thought it would be a good idea to grep for each chromosome in the data.bed and windows.bed and pipe that input to the coverageBed command. How do I simultaneously grep from two files and pass the two outputs to coverageBed? I figured how I can pipe one file (shown below), but struggling with piping two files simultaneously.
grep -w 'chr[1]' data.bed| coverageBed -counts -a stdin -b ExtraFiles_for_Analysis/windows_chr1.bed | sortBed -i stdin > chr1_coverage.txt

In the above command, windows_chr1.bed is the file containing only the windows in chromosome-1, which I had to create separately. So my goal is not to create separate files for each chromosomes a priori, and instead be able to create that in the same line.

And secondly, can I use some loop so that I can do this for each chromosome?
I searched a lot in online forums and couldn't get anything.
Thanks for any help or pointers.
Hari

[kmcarr]

You could do this with named pipes.

mkfifo data
mkfifo windows

This will create two special files in the current directory named data and windows respectively.

grep -w 'chr[1]' data.bed > data &
grep -w 'chr[1]' windows.bed > windows &

coverageBed -counts -a data -b windows | sortBed -i stdin > chr1_coverage.txt

When the coverageBed task completes the grep jobs in the background will terminate. You can then reuse the same named pipes while iterating through each of the chromosomes.

[lh3]

coverageBed -counts -a <(grep chr1 data.beg) -b <(grep chr1 windows.beg)

[syfo]

coverageBed -counts -a <(grep chr1 data.beg) -b <(grep chr1 windows.beg)

That looks great, thanks.
Of course do not forget the "-w" option to only grep the chr1 and not chr10, chr11 etc (I would actually use awk ' $1=="chr1" ' < data.bed).