This is a straightforward command-line tool that knows how to generate files
containing license text, and how to inject license comments into source files.
# Write a LICENSE.txt containing a BSD 3-clause license.
lice -write LICENSE.txt -L bsd3c
# Add comment headers to Go files for the GPLv3.
lice -edit -L gplv3 *.go
Run lice -help for online help.