I have two commits with multiline messages. But in bother cases on github I see only first line.
commit da202cdb5085290a6498c434a0d9388d880fe8c8 Date: Tue Oct 1 16:30:02 2013 +0200 Line 1 Line 2 commit c58f91213428728836b1364ecc111ba71e7c91c6 Date: Tue Oct 1 15:47:12 2013 +0200 [f] unique primary key for id in picture [+] join_db script https://github.com/antofa/autowp_test/commits/dev
I use next commands for commits:
git commit -F commit_message.txt
git commit -m "Line 1" -m "Line 2"
Can github work with multiline commit messages and how?

git commit, then typed a commit message with new lines in it? I've not run into that issue...and I would imagine that GitHub would be fine with it, too.