### Start Luke with JAR

Source: https://github.com/apache/lucene/blob/main/lucene/luke/src/distribution/README.md

Use this command to start Luke when running from a JAR file. Ensure the correct Java version is installed.

```bash
java -jar ${luke.cmd}
```

--------------------------------

### Interactive Program Notice Example

Source: https://github.com/apache/lucene/blob/main/lucene/demo/src/test/org/apache/lucene/demo/test-files/docs/gpl1.0.txt

Display this short notice when an interactive program starts to inform users about its version, warranty, and redistribution conditions. The commands like `show w` and `show c` should display relevant license details.

```text
Gnomovision version 69, Copyright (C) 19xx name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
```

--------------------------------

### Display All Gradle Help Guides

Source: https://github.com/apache/lucene/blob/main/CONTRIBUTING.md

Execute this command to view all available help guides that explain various parts of the build system.

```bash
./gradlew help
```

--------------------------------

### Start Luke with Java Modules

Source: https://github.com/apache/lucene/blob/main/lucene/luke/src/distribution/README.md

This command starts Luke using Java modules. It requires specifying the module path and adding the 'jdk.unsupported' module.

```bash
java --module-path . --add-modules jdk.unsupported --module org.apache.lucene.luke
```

--------------------------------

### BoostingQuery Example

Source: https://github.com/apache/lucene/blob/main/lucene/queryparser/docs/xml/LuceneContribQuery.dtd.html

Illustrates how to use BoostingQuery to find documents matching a primary query while optionally boosting or de-boosting based on a secondary query. This example finds documents about banks, preferably related to mergers, and preferably not about 'World bank'.

```xml
<BoostingQuery>
    <Query>
      <BooleanQuery fieldName="contents">
        <Clause occurs="should">
          <TermQuery>merger</TermQuery>
        </Clause>
        <Clause occurs="must">
          <TermQuery>bank</TermQuery>
        </Clause>
      </BooleanQuery>
    </Query>
    <BoostQuery boost="0.01">
      <UserQuery>"world bank"</UserQuery>
    </BoostQuery>
  </BoostingQuery>
```

--------------------------------

### BM25 Similarity Implementation in Lucene

Source: https://github.com/apache/lucene/blob/main/lucene/CHANGES.txt

Example of how to set the BM25 similarity for all fields in an IndexSearcher. For per-field configurations, implement PerFieldSimilarityWrapper.

```java
searcher.setSimilarity(new BM25Similarity());
```

--------------------------------

### Get Matched Text

Source: https://github.com/apache/lucene/blob/main/gradle/regenerate/jflex/skeleton.disable.buffer.expansion.txt

Returns the actual text that was matched by the current regular expression. This is constructed from the buffer using start and marked positions.

```Java
public final String yytext() {
    return new String(zzBuffer, zzStartRead, zzMarkedPos-zzStartRead);
  }
```

--------------------------------

### Get Matched Text Length

Source: https://github.com/apache/lucene/blob/main/gradle/regenerate/jflex/skeleton.disable.buffer.expansion.txt

Returns the length of the text matched by the current regular expression. This is calculated as the difference between the marked and start read positions.

```Java
public final int yylength() {
    return zzMarkedPos-zzStartRead;
  }
```

--------------------------------

### Install Python Modules

Source: https://github.com/apache/lucene/blob/main/dev-tools/scripts/README.md

Installs necessary Python modules for development scripts. Requires Python 3.12 or above.

```bash
make env
source .env/bin/activate
```

--------------------------------

### Check Dependency Licenses and Notices

Source: https://github.com/apache/lucene/blob/main/help/dependencies.txt

Verify that licenses, notice files, and checksums are in place for all new dependencies. This command reports any missing information.

```bash
gradlew licenses
```

--------------------------------

### Index and Search Text with Lucene

Source: https://github.com/apache/lucene/blob/main/lucene/core/src/java/overview.html

This example demonstrates how to index a simple text document and then search it using Apache Lucene. It covers setting up the analyzer, directory, index writer, document creation, and performing a search query. Ensure JUnit is available for assertions.

```java
Analyzer analyzer = new StandardAnalyzer();
    
    Path indexPath = Files.createTempDirectory("tempIndex");
    try (Directory directory = FSDirectory.open(indexPath)) {
      IndexWriterConfig config = new IndexWriterConfig(analyzer);
      try (IndexWriter iwriter = new IndexWriter(directory, config)) {
        Document doc = new Document();
        String text = "This is the text to be indexed.";
        doc.add(new Field("fieldname", text, TextField.TYPE_STORED));
        iwriter.addDocument(doc);
      }
    
      // Now search the index:
      try (DirectoryReader ireader = DirectoryReader.open(directory)) {
        IndexSearcher isearcher = new IndexSearcher(ireader);
        // Parse a simple query that searches for "text":
        QueryParser parser = new QueryParser("fieldname", analyzer);
        Query query = parser.parse("text");
        ScoreDoc[] hits = isearcher.search(query, 10).scoreDocs;
        assertEquals(1, hits.length);
        // Iterate through the results:
        StoredFields storedFields = isearcher.storedFields();
        for (int i = 0; i < hits.length; i++) {
          Document hitDoc = storedFields.document(hits[i].doc);
          assertEquals("This is the text to be indexed.", hitDoc.get("fieldname"));
        }
      }
    } finally {
      IOUtils.rm(indexPath);
    }
```

--------------------------------

### Format Code with Gradle

Source: https://github.com/apache/lucene/blob/main/help/workflow.txt

Run this command to ensure your code changes adhere to the project's formatting standards. Refer to ':helpFormatting' for more details.

```gradle
gradlew tidy
```

--------------------------------

### Install Xvfb on Arch Linux

Source: https://github.com/apache/lucene/blob/main/help/tests.txt

Installs Xvfb using the pacman package manager. This is a prerequisite for certain testing scenarios on Arch Linux.

```bash
$ sudo pacman -S xorg-server-xvfb
```

--------------------------------

### BooleanQuery Example

Source: https://github.com/apache/lucene/blob/main/lucene/queryparser/docs/xml/LuceneContribQuery.dtd.html

Demonstrates how to construct a BooleanQuery with 'should', 'mustnot', and 'must' clauses to define complex search criteria.

```xml
<BooleanQuery fieldName="contents">
    <Clause occurs="should">
      <TermQuery>merger</TermQuery>
    </Clause>
    <Clause occurs="mustnot">
      <TermQuery>sumitomo</TermQuery>
    </Clause>
    <Clause occurs="must">
      <TermQuery>bank</TermQuery>
    </Clause>
  </BooleanQuery>
```

--------------------------------

### Install Xvfb on Ubuntu/Debian-based systems

Source: https://github.com/apache/lucene/blob/main/help/tests.txt

Installs Xvfb using the apt package manager. This is a prerequisite for certain testing scenarios on Ubuntu or Debian.

```bash
$ sudo apt install xvfb
```

--------------------------------

### Install Precommit Hook

Source: https://github.com/apache/lucene/blob/main/help/precommit.txt

Install a precommit hook to automatically run checks before each commit. The '--allow-missing-config' option is needed for older release branches.

```bash
uv tool install prek
prek install --allow-missing-config
```