One thing you could do is get (or generate) a BED or GFF file that lists each exon coordinate. Then use the mergeBed tool in bedtools to create longer intervals, finally all you need is to add up the lengths of the merged intervals.

using a GFF or GTF file for example using "gencode.v7.annotation_goodContig.gtf" file

to print number of bases in gene regions:

cat  gencode.v7.annotation_goodContig.gtf | awk '/gene/ { len +=$5-$4} END {print len}'

Similarly you can extract information for other regions ....