import subprocess
with open('/mnt/data/catlas_downloads/JASPAR/humanbrain_cCREs.bed','r') as am:
    for line in am:
        aa=line.rstrip().split('\t')
        cmd='/var/www/html/software/conda/envs/catlas/bin/bigBedToBed -chrom={0} -start={1} -end={2} /mnt/data/resource/dbSnp153.bb test.bed\ncat test.bed >>result.bed\nrm -f test.bed'.format(aa[0],aa[1],aa[2])
        subprocess.call(cmd,shell=True)