Prometheus 导出器，用于 *NIX 内核公开的硬件和操作系统指标，用 Go 编写，带有可插拔指标收集器

# Kingpin - A Go (golang) command line and flag parser [](http://godoc.org/github.com/alecthomas/kingpin) [](https://travis-ci.org/alecthomas/kingpin) [](https://gitter.im/alecthomas/Lobby) <!-- MarkdownTOC --> - [Overview](#overview) - [Features](#features) - [User-visible changes between v1 and v2](#user-visible-changes-between-v1-and-v2) - [Flags can be used at any point after their definition.](#flags-can-be-used-at-any-point-after-their-definition) - [Short flags can be combined with their parameters](#short-flags-can-be-combined-with-their-parameters) - [API changes between v1 and v2](#api-changes-between-v1-and-v2) - [Versions](#versions) - [V2 is the current stable version](#v2-is-the-current-stable-version) - [V1 is the OLD stable version](#v1-is-the-old-stable-version) - [Change History](#change-history) - [Examples](#examples) - [Simple Example](#simple-example) - [Complex Example](#complex-example) - [Reference Documentation](#reference-documentation) - [Displaying errors and usage information](#displaying-errors-and-usage-information) - [Sub-commands](#sub-commands) - [Custom Parsers](#custom-parsers) - [Repeatable flags](#repeatable-flags) - [Boolean Values](#boolean-values) - [Default Values](#default-values) - [Place-holders in Help](#place-holders-in-help) - [Consuming all remaining arguments](#consuming-all-remaining-arguments) - [Bash/ZSH Shell Completion](#bashzsh-shell-completion) - [Supporting -h for help](#supporting--h-for-help) - [Custom help](#custom-help) <!-- /MarkdownTOC --> ## Overview Kingpin is a [fluent-style](http://en.wikipedia.org/wiki/Fluent_interface), type-safe command-line parser. It supports flags, nested commands, and positional arguments. Install it with: $ go get gopkg.in/alecthomas/kingpin.v2 It looks like this: ```go var ( verbose = kingpin.Flag("verbose", "Verbose mode.").Short('v').Bool() name = kingpin.Arg("name", "Name of user.").Required().String() ) func main() { kingpin.Parse() fmt.Printf("%v, %s\n", *verbose, *name) } ``` More [examples](https://github.com/alecthomas/kingpin/tree/master/_examples) are available. Second to parsing, providing the user with useful help is probably the most important thing a command-line parser does. Kingpin tries to provide detailed contextual help if `--help` is encountered at any point in the command line (excluding after `--`). ## Features - Help output that isn't as ugly as sin. - Fully [customisable help](#custom-help), via Go templates. - Parsed, type-safe flags (`kingpin.Flag("f", "help").Int()`) - Parsed, type-safe positional arguments (`kingpin.Arg("a", "help").Int()`). - Parsed, type-safe, arbitrarily deep commands (`kingpin.Command("c", "help")`). - Support for required flags and required positional arguments (`kingpin.Flag("f", "").Required().Int()`). - Support for arbitrarily nested default commands (`command.Default()`). - Callbacks per command, flag and argument (`kingpin.Command("c", "").Action(myAction)`). - POSIX-style short flag combining (`-a -b` -> `-ab`). - Short-flag+parameter combining (`-a parm` -> `-aparm`). - Read command-line from files (`@<file>`). - Automatically generate man pages (`--help-man`). ## User-visible changes between v1 and v2 ### Flags can be used at any point after their definition. Flags can be specified at any point after their definition, not just *immediately after their associated command*. From the chat example below, the following used to be required: ``` $ chat --server=chat.server.com:8080 post --image=~/Downloads/owls.jpg pics ``` But the following will now work: ``` $ chat post --server=chat.server.com:8080 --image=~/Downloads/owls.jpg pics ``` ### Short flags can be combined with their parameters Previously, if a short flag was used, any argument to that flag would have to be separated by a space. That is no longer the case. ## API changes between v1 and v2 - `ParseWithFileExpansion()` is gone. The new parser directly supports expanding `@<file>`. - Added `FatalUsage()` and `FatalUsageContext()` for displaying an error + usage and terminating. - `Dispatch()` renamed to `Action()`. - Added `ParseContext()` for parsing a command line into its intermediate context form without executing. - Added `Terminate()` function to override the termination function. - Added `UsageForContextWithTemplate()` for printing usage via a custom template. - Added `UsageTemplate()` for overriding the default template to use. Two templates are included: 1. `DefaultUsageTemplate` - default template. 2. `CompactUsageTemplate` - compact command template for larger applications. ## Versions Kingpin uses [gopkg.in](https://gopkg.in/alecthomas/kingpin) for versioning. The current stable version is [gopkg.in/alecthomas/kingpin.v2](https://gopkg.in/alecthomas/kingpin.v2). The previous version, [gopkg.in/alecthomas/kingpin.v1](https://gopkg.in/alecthomas/kingpin.v1), is deprecated and in maintenance mode. ### [V2](https://gopkg.in/alecthomas/kingpin.v2) is the current stable version Installation: ```sh $ go get gopkg.in/alecthomas/kingpin.v2 ``` ### [V1](https://gopkg.in/alecthomas/kingpin.v1) is the OLD stable version Installation: ```sh $ go get gopkg.in/alecthomas/kingpin.v1 ``` ## Change History - *2015-09-19* -- Stable v2.1.0 release. - Added `command.Default()` to specify a default command to use if no other command matches. This allows for convenient user shortcuts. - Exposed `HelpFlag` and `VersionFlag` for further customisation. - `Action()` and `PreAction()` added and both now support an arbitrary number of callbacks. - `kingpin.SeparateOptionalFlagsUsageTemplate`. - `--help-long` and `--help-man` (hidden by default) flags. - Flags are "interspersed" by default, but can be disabled with `app.Interspersed(false)`. - Added flags for all simple builtin types (int8, uint16, etc.) and slice variants. - Use `app.Writer(os.Writer)` to specify the default writer for all output functions. - Dropped `os.Writer` prefix from all printf-like functions. - *2015-05-22* -- Stable v2.0.0 release. - Initial stable release of v2.0.0. - Fully supports interspersed flags, commands and arguments. - Flags can be present at any point after their logical definition. - Application.Parse() terminates if commands are present and a command is not parsed. - Dispatch() -> Action(). - Actions are dispatched after all values are populated. - Override termination function (defaults to os.Exit). - Override output stream (defaults to os.Stderr). - Templatised usage help, with default and compact templates. - Make error/usage functions more consistent. - Support argument expansion from files by default (with @<file>). - Fully public data model is available via .Model(). - Parser has been completely refactored. - Parsing and execution has been split into distinct stages. - Use `go generate` to generate repeated flags. - Support combined short-flag+argument: -fARG. - *2015-01-23* -- Stable v1.3.4 release. - Support "--" for separating flags from positional arguments. - Support loading flags from files (ParseWithFileExpansion()). Use @FILE as an argument. - Add post-app and post-cmd validation hooks. This allows arbitrary validation to be added. - A bunch of improvements to help usage and formatting. - Support arbitrarily nested sub-commands. - *2014-07-08* -- Stable v1.2.0 release. - Pass any value through to `Strings()` when final argument. Allows for values that look like flags to be processed. - Allow `--help` to be used with commands. - Support `Hidden()` flags. - Parser for [units.Base2Bytes](https://github.com/alecthomas/units)