headache manages license headers. It is biased towards Golang but should work on any other language (provided a compatible code comment style is implemented).

By default, headache looks for a configuration file named headache.json in the directory in which it is invoked:

{
  "headerFile": "./license-header.txt",
  "style": "SlashStar",
  "includes": ["**/*.go"],
  "excludes": ["vendor/**/*"],
  "data": {
    "Owner": "The original author or authors"
  }
}

license-header.txt (note the absence of YearRange parameter in the configuration file):

Copyright {{.YearRange}} {{.Owner}}

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

All you have to do then is:

 $ go get -u github.com/fbiville/headache
 $ $(GOBIN)/headache

As a result, source files will be changed and .headache-run will be generated to keep track of headache last execution. This file must be versioned along with the source file changes.

Alternatively, the configuration file can be explicitly provided:

 $ go get -u github.com/fbiville/headache
 $ $(GOBIN)/headache --configuration /path/to/configuration.json

headache approach to copyright is well explained in this stackoverflow answer, read it first!

Now that you read this, here are two important points:

• Copyright years have to be updated when a significant change occurs.

There is, to the author knowledge, no automatic solution to distinguish a trivial change from a significant one.

Based on this premise, headache will process all files matching the configuration and that have been changed since its last execution. headache will then compute the copyright year, file by file, from their available versioning information (typically by retrieving the relevant dates from Git commits).

It is up to the project maintainer to discard the generated changes if they are not relevant.

• The [first] date on the [copyright] notice establishes how far back the claim is made.

This claim could predate any commit associated to the file (imagine a file copied from project to project for years).

headache will never overwrite the start date of the copyright year if it finds one, if and only if that date occurs earlier than the first commit date of the file.

headache relies on the emerging JSON Schema standard to validate its configuration. headache schema is defined here.

In layman's terms, here are all the possible settings:

• {{.YearRange}} (formerly {{.Year}}) is automatically substituted with either:
  • a single year if both years in the range are the same
  • a year range with the earliest commit's year* and latest commit's year
• {{.StartYear}} is substituted with the earliest commit's year
• {{.EndYear}} is substituted with the latest commit's year

As explained earlier, if a file specifies a start date in its header that is earlier than any commit's year, then that date is preserved.

If you want to avoid copyright dates like 2019-2019, then rely on {{.YearRange}}. If you need something like 2018-present, then use {{.StartYear}}-present instead.