I'm using geneBody_coverage2.py in RseQC package to calculate Read coverage over gene body, which need a bed12 file.  I did alignment  based on   Homo_sapiens.GRCh38.84.gtf , so i need a Homo_sapiens.GRCh38.84.bed.  But  gtfToBed can't  produce a BED12 file,  how can I get it? anyone can help me? 
`awk '{if($3 != "gene") print $0}' Homo_sapiens.GRCh38.84.gtf | grep -v "^#" | gtfToGenePred /dev/stdin /dev/stdout | genePredToBed stdin Homo_sapiens.GRCh38.84.bed`

You can download the two tools from UCSC.

If you're curious, this is from [here](https://github.com/maxplanck-ie/data_repository/blob/master/organisms/Makefile.inc#L56-L59) and is essentially the code I use to generate the reference data for our institute.