Nano and Less Customization

Customization

Both nano and less commands can be customized using nanorc like configuration files: jnanorc and jlessrc.

Java

ConfigurationPath configPath = new ConfigurationPath(Paths.get("/pub/myApp"),   // application-wide settings
                       Paths.get(System.getProperty("user.home"), ".myApp"));   // user-specific settings

Supplier<Path> workDir = () -> Paths.get("");
Builtins builtins = new Builtins(workDir, configPath, null);
SystemRegistry systemRegistry = new SystemRegistry(parser, terminal, workDir, configPath);
systemRegistry.setCommandRegistries(builtins);

LineReader reader = LineReaderBuilder.builder()
                    .terminal(terminal)
                    .completer(systemRegistry.completer())
                    .parser(parser)
                    .build();

builtins.setLineReader(reader);
while (true) {
    try {
        systemRegistry.cleanUp();         // delete temporary variables and reset output streams
        String line = reader.readLine(prompt, rightPrompt, (MaskingCallback) null, null);
        Object result = systemRegistry.execute(line);
        .....
        .....
        .....
    }
    catch (UserInterruptException e) {
        // Ignore
    }
    catch (EndOfFileException e) {
        return;
    }
    catch (Exception e) {
        systemRegistry.trace(e);          // print exception and save it to console variable
    }
 }

Options

The jnanorc/jlessrc file contains the default settings for nano/less. During startup, the command try first read the user-specific settings and then its application-wide settings. Application-wide settings are read only if user-specific settings does not exists.

The configuration file accepts a series of set and unset commands, which can be used to configure nano/less on startup without using the command line options.

In addition configuration file might have 'include syntaxfile' commands to read self-contained color syntaxes from syntaxfile. Syntax file parameter can have '*' and '?' wildcards in its file name.

In a case that neither of application-wide nor user-specific settings are not found at command startup then syntaxfiles are searched from a standard installation location: /usr/share/nano.

Example: Configuration file jnanorc. Note that historylog is saved in user-specific directory and the file can be shared between nano and less applications.

include /usr/share/nano/*.nanorc
set tabstospaces
set autoindent
set tempfile
set historylog search.log

Theme system

JLine version > 3.21.0

Theme system allows highlight rules to be specified in terms of token type names, mixins and parser configurations, instead of hard-coded colors in nanorc files. Optional theme system configuration is set by adding 'theme theme-system-file' command in jnanorc/jlessrc configuration files.

Theme system idea has been copied from YSakhno/nanorc and adopted to JLine.

Syntax highlight

JLine nanorc SyntaxHighlighter works with standard nanorc syntaxfiles.

JLine supported keywords: the syntax, color, and icolor are used to define syntax highlighting rules for different text patterns. Other nanorc keywords are quietly ignored.

Rebinding keys

Not supported.