Get start and end coordinates per chromosome
Not sure if I completely understood your question, but if you want simply an interval of your entire genome  you could do instead:

samtools faidx MyGenome.fasta


Obviously that means that you need access to that, not sure if you have.
The resulting fai file contains a format similar to that:

000000F 33203223        94      60      61
000001F 28828106        33756799        60      61
000002F 27810542        63065468        60      61


Where the first column is your chromosome and the second one your length.
I guess you could then just do a awk '{OFS=FS="\t"}{print $1,"0",$2-1}' to get your file.