Commands
# protein alignment - JTT+CAT model
fasttree protein_alignment > tree
# nucleotide alignment
fasttree -nt nucleotide_alignment > tree
# nucleotide alignment - GTR+CAT model
fasttree -nt -gtr nucleotide_alignment > tree
References
Manual
http://manpages.ubuntu.com/manpages/trusty/man1/fasttree.1.html
Website
http://www.microbesonline.org/fasttree/