A GUID generator written in C# using the scripting mode of `csharp`

guid.cs

#!/usr/bin/env csharp -s

string error = null;
var showHelp = false;
var count = 1u;
var format = "D";
var upper = false;
var bojangles = false;

for (int i = 0; i < Args.Length && error == null; i++) {
	switch (Args [i]) {
	case "-h":
	case "/h":
	case "-?":
	case "/?":
	case "-help":
	case "--help":
	case "/help":
		showHelp = true;
		break;
	case "-n":
	case "/n":
		if (i < Args.Length - 1) {
			if (!uint.TryParse (Args [++i], out count))
				error = "-n requires a positive integer";
		} else
			error = "number not provided";
		break;
	case "-u":
	case "/u":
	case "-upper":
	case "--upper":
	case "/upper":
		upper = true;
		break;
	case "-f":
	case "/f":
	case "-format":
	case "--format":
	case "/format":
		if (i < Args.Length - 1) {
			format = Args [++i].ToUpperInvariant ();
			switch (format) {
			case "N":
			case "D":
			case "B":
			case "P":
			case "X":
				break;
			default:
				error = $"invalid format specifier '{Args[i]}'";
				break;
			}
		} else
			error = "format not provided";
		break;
	case "-b":
	case "/b":
	case "-bojangles":
	case "--bojangles":
	case "/bojangles":
		bojangles = true;
		break;
	default:
		error = $"invalid argument `{Args [i]}`";
		break;
	}
}

if (error != null) {
	Console.Error.WriteLine ("error: {0}", error);
	Console.Error.WriteLine ();
	showHelp = true;
}

if (showHelp) {
	Console.WriteLine (@"usage: guid [OPTIONS]
 
OPTIONS:
    -help, -h           show this help
    -format, -f FORMAT  ToString format to use (see FORMATS)
    -upper, -u          uppercase GUID
    -n NUMBER           produce NUMBER GUIDs
    -bojangles, -b      produces GUIDs with all 'AA' strings
                        replaced with 'BB' strings
 
FORMATS:
    N    32 digits:
         00000000000000000000000000000000
 
    D    32 digits separated by hyphens:
         00000000-0000-0000-0000-000000000000
 
    B    32 digits separated by hyphens, enclosed in braces:
         {{00000000-0000-0000-0000-000000000000}}
 
    P    32 digits separated by hyphens, enclosed in parentheses:
         (00000000-0000-0000-0000-000000000000)
 
    X    Four hexadecimal values enclosed in braces, where the
         fourth value is a subset of eight hexadecimal values
         that is also enclosed in braces:
         {0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}
");
	Environment.Exit (1);
}

for (uint i = 0; i < count; i++) {
	var guid = Guid.NewGuid ().ToString (format);
	if (upper) {
		guid = guid.ToUpperInvariant ();
		if (bojangles)
			guid = guid.Replace ("AA", "BB");
	} else if (bojangles)
		guid = guid.Replace ("aa", "bb");

	Console.WriteLine (guid);
}

Unfortunately Linux doesn't split the argument in #!. So if you use /usr/bin/env, then it tries to use csharp -s as the literal executable name... (Which could be symlinked actually, but it'd be weird.)

You could use dotnet core csharp interactive: csi