Line limit of bedtools getfasta and other sub-commands?

[YuanfengZhang]

When passing a sorted bed file containing more than 20 billion lines of genomic regions to getfasta, I only got the results of chr1, chr10 and chr11. The rows behind them were ignored. By the way, I'm sure the RAM is abundant (1TB 3200MHz).

I searched the closed issues and bedtools documentation but didn't get a proper answer. I know I can avoid this by separating single file to multiple small files, but I'm just curious that does bedtools have a line limit which is not described in the doc, or it's more likely to be a buffer/tmp file issue on my Ubuntu server?

Thanks for your help in advance.