BLAST (not BLAST+) provides an option for tabular output that is easily parsed. Use the -m 8 option for tabular output, or the -m 9 option to include headers.

blastall -i input.fa -d /path/to/db.fa -p blastn -m 8

Assumes that db.fa is in a directory that also has a correctly formatted database. This can be achieved by:

formatdb -i db.fa -p F

The fields for tabular BLAST output are: Parse the information:

Python

for line in open(“myfile.blast”):
(queryId, subjectId, percIdentity, alnLength, mismatchCount, gapOpenCount, queryStart, queryEnd, subjectStart, subjectEnd, eVal, bitScore) = line.split(“t”)

Perl

while (<>) {
($queryId, $subjectId, $percIdentity, $alnLength, $mismatchCount, $gapOpenCount, $queryStart, $queryEnd, $subjectStart, $subjectEnd, $eVal, $bitScore) = split(/t/)
}