Hi all, I have several millions of records with format `chromosome  position` like:

```
chr1 10001
chr1 144244
chr2 ...
```

And I know it is from human hg19. Now I want to get the ATGC info for each position so it would become:

```
chr1 10001 A
chr1 144244 G
chr2 ...
```

Anyone know what is the best practice for such job. Tools like UCSC table work for single record, but too slow for a lot of them.
`bedtools getfasta` will also work for this job. You should create a bed file with the chromosome start and end positions that you'd like to extract:

    chr1 10001 10002
    chr1 144244 144245
    ...

