I need to extract the genome sequence of >10000 regions. For one example:

samtools faidx GRCh38.primary_assembly.genome.fa chr12:9074800-9074802

output:

AGA

But there are >10000 output. I don't know how to efficiently concatenate them into one single file just like:

AGA
GTA
GG
ATC
TGG
..
..
..

A possible solution I could find out is adding samtools faidx GRCh38.primary_assembly.genome.fa chr12:9074800-9074802> 1.txt to create >10000 files. Then I concatenate all these files using other scripts. But it looks stupid.

Is there any other way to achieve this purpose? Thank you.