RPKM normalize ATAC-seq bigwigs

#!/usr/bin/bash
CI=/local/storage/projects/prophaseI/data/scaled_files/mm10.chromInfo.sizes
function getCountsBw {
        bigWigToBedGraph ${1}.bw tmp.plus.bedGraph ## NOTE THE USE OF mm10 coords here.  We're normalizing to mm10.
        cat tmp.plus.bedGraph  | awk '{print $4}' | gzip >  $1.counts.gz
        READCOUNTS=`zcat $1.counts.gz | awk 'function abs(value){return (value<0?-value:value);}; {sum+=abs($1)} END {print sum}'`
        rm tmp.plus.bedGraph tmp.minus.bedGraph $1.counts.gz
}
function normBw {
        bigWigToBedGraph ${1}.bw tmp.bedGraph ## NOTE THE USE OF hg19 coords here.  We're normalizing to hg19.
        cat tmp.bedGraph | awk 'BEGIN{OFS="\t"} {print $1,$2,$3,$4*1000*1000/'$2'/1}' > tmp.rpkm.bedGraph
        bedGraphToBigWig tmp.rpkm.bedGraph $CI $1.rpkm.bw
        rm tmp.bedGraph tmp.rpkm.bedGraph
}
fileprefix=`ls *.bw | cut -d \. -f 1 | rev | cut -d _ -f2- | rev | uniq`
## Get post-liftOver counts.
for i in $fileprefix
do
        echo $i
        getCountsBw $i
        echo $READCOUNTS
        normBw ${i}  $READCOUNTS
done