bash N.sh test.fasta chr1
  you will get test.fasta.chr1.1-based.bed
 
 

hg19=ucsc.hg19.fasta
cat $hg19 | grep '^>chr' | sed 's/>//' | xargs -i -P 24 bash N.sh $hg19 {}
cat *hg19*.chr*.1-based.bed >hg19.N-Region
  you will get hg19.N-Region
cat hg19.N-Region | awk '{print $3-$2+1}' | datamash sum 1 will output 239850802 identical with http://genomewiki.ucsc.edu/index.php/Hg19_Genome_size_statistics