bab1c13e_ling_BioPerl_on_Unix___BioPerl__Description
[Env. Variable] BLASTDIR [Description] 
Specifies where the NCBI blastall, blastpgp, bl2seq, etc.. are located. A 'data' directory could also be present in this directory as well, you could put your blastable databases here.
Installing BioPerl on Unix - BioPerl
Description