Options.cs

using CommandLine;
using CommandLine.Text;

namespace csvcat;

public class Options
{
    [Value(0, MetaName = "csv file", Required = true)]
    public string Filename { get; set; }

    [Option('n', "number", Default = 0, HelpText = "Number of lines.")]
    public int Lines { get; set; }

    [Option('t', "tail", Default = false, HelpText = "Tail csv file")]
    public bool Tail { get; set; }

    [Option('s', "sort", HelpText = "Sort by field index (0-based)")]
    public int? Sort { get; set; }

    [Option('r', "reverse", Default = false, HelpText = "Reverse results")]
    public bool Reverse { get; set; }

    [Option('d', "delimiter", Default = ',', HelpText = "Delimiting character. Default = ','")]
    public char Delimiter { get; set; }

    [Usage(ApplicationAlias = "csvcat")]
    public static IEnumerable<Example> Examples
    {
        get
        {
            yield return new Example("cat csv file", new Options { Filename = "file.csv", Lines = 20 });
            yield return new Example("tail csv file", new Options { Filename = "file.csv", Lines = 30, Tail = true, Delimiter = '|' });
        }
    }
    public static void DisplayHelp<T>(ParserResult<T> result, IEnumerable<Error> errs)
    {
        HelpText helpText = errs.IsVersion() ? HelpText.AutoBuild(result)   
            : HelpText.AutoBuild(result, h =>
                {
                    h.AdditionalNewLineAfterOption = false;
                    h.Heading = "csvcat 1.1.2";
                    h.Copyright = "Copyright (c) 2023 lc9er";
                    return HelpText.DefaultParsingErrorsHandler(result, h);
                }, e => e);

        Console.WriteLine(helpText);
    }
}