README.md
1# License Classifier
2
3[](https://travis-ci.org/google/licenseclassifier)
4
5## Introduction
6
7The license classifier is a library and set of tools that can analyze text to
8determine what type of license it contains. It searches for license texts in a
9file and compares them to an archive of known licenses. These files could be,
10e.g., `LICENSE` files with a single or multiple licenses in it, or source code
11files with the license text in a comment.
12
13A "confidence level" is associated with each result indicating how close the
14match was. A confidence level of `1.0` indicates an exact match, while a
15confidence level of `0.0` indicates that no license was able to match the text.
16
17## Usage
18
19### One-time setup
20
21Use the `license_serializer` tool to regenerate the `licenses.db` archive.
22The archive contains preprocessed license texts for quicker comparisons against
23unknown texts.
24
25```shell
26$ go run tools/license_serializer/license_serializer.go -output licenses
27```
28
29### Identifying licenses
30
31Use the `identify_license` command line tool to identify the license(s)
32within a file.
33
34```shell
35$ go run tools/identify_license/identify_license.go /path/to/LICENSE
36LICENSE: GPL-2.0 (confidence: 1, offset: 0, extent: 14794)
37LICENSE: LGPL-2.1 (confidence: 1, offset: 18366, extent: 23829)
38LICENSE: MIT (confidence: 1, offset: 17255, extent: 1059)
39```
40
41## Adding a new license
42
43Adding a new license is straight-forward:
44
451. Create a file in `licenses/`.
46
47 * The filename should be the name of the license or its abbreviation. If
48 the license is an Open Source license, use the appropriate identifier
49 specified at https://spdx.org/licenses/.
50 * If the license is the "header" version of the license, append the suffix
51 "`.header`" to it. See `licenses/README.md` for more details.
52
532. Add the license name to the list in `license_type.go`.
54
553. Regenerate the `licenses.db` file by running the license serializer:
56
57 ```shell
58 $ license_serializer -output licenseclassifier/licenses
59 ```
60
614. Create and run appropriate tests to verify that the license is indeed
62 present.
63
64----
65This is not an official Google product (experimental or otherwise), it is just
66code that happens to be owned by Google.
67
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