gff2bed和gtf2bed都是BEDOPS的程序；所以使用之前需要安装# BEDOPS；
软件安装
$ git clone https://github.com/bedops/bedops.git
$ cd bedops
$ make
$ make install
GFF格式转bed
gff2bed <gencode.v19.annotation.gff3 > test.bed
convert2bed -i gff -o bed <gencode.v19.annotation.gff3 > test.bed
GTF格式转bed
gtf2bed <gencode.v19.annotation.gtf > test.bed
convert2bed -i gtf -o bed <gencode.v19.annotation.gtf > test.bed
