perl -lpe "}{${'~'^'!'}=$." file
[download]

Note: I get a problem running this under bash, because it interprets the ! incorrectly. But stick it in a file and it will run correctly. e.g.,

#!/usr/bin/perl -lp
}{${'~'^'!'}=$.
[download]

Update: fixed a typo, and I forgot to put file on the command line. And here's a new version that actually runs on the command line:

perl -lpe '}{${"#"^"|"}=$.' file
[download]

-- Mike

--
just,my${.02}