module examples.env; import std.stdio; import std.conv; import std.process; import cmdline; void main(in string[] argv) { environment["BAR"] = "env"; program.name("env"); Option env_opt = createOption!string("-f, --foo <required-arg>"); env_opt.env("BAR"); program.addOption(env_opt); program.addHelpText(AddHelpPos.Before, ` Try the following: $ env $ env -fxx `); program.parse(argv); OptsWrap opts = program.getOpts; string foo = opts("foo").get!string; auto src = program.getOptionValSource("foo"); writefln("-f, --foo <%s>, from %s", foo, src.to!string); }