xo/ox

xo/ox is a Go and TinyGo package for command-line argument and flag parsing.

Using | Example | Applications | About | License

Features

• Long (--arg, --arg val) and Short (-a, -a val) flag parsing
• POSIX-style/compatible flag parsing (-vvv, -mfoo=bar -m foo=bar, --map=foo=bar)
• Flags can have optional arguments (via NoArg) and type specific defaults
• Full command tree and sub command heirarchy
• Support for all scalars:
  • []byte, string, []rune, byte, rune
  • int64, int32, int16, int8, int
  • uint64, uint32, uint16, uint8, uint
  • float64, float32
  • complex128, complex64
• Support for standard library types:
  • time.Time, time.Duration
  • *big.Int, *big.Float, *big.Rat
  • *url.URL, *regexp.Regexp
  • *netip.Addr, *netip.AddrPort, *netip.Prefix
• Support for compound types of all above (slices/maps):
  • []int, [][]byte, []string, []float64, []*big.Int, etc.
  • map[string]string, map[int]string, map[float64]*url.URL, etc.
• Additional type support:
  • ox.DateTimeT, ox.DateT, ox.TimeT / type:datetime, type:date, type:time - standard dates and times
  • ox.FormattedTime - any time.Time value using any time.Layout format
  • ox.CountT / type:count - incrementing counter, such as for verbosity -vvvv
  • ox.ByteCountT - a SI or IEC formatted byte count
  • ox.Base64T - a base64 encoded string
  • ox.HexT - a hex encoded string
  • ox.PathT / type:path - a file system path
  • ox.HookT - argument func hook, for hooking flags
• Optional, common types, available with optional import:
  • *github.com/google/uuid.UUID - standard UUID's
  • *github.com/kenshaw/colors.Color - named and css style colors (white, black, #ffffff, RGBA(...), ...)
  • *github.com/gobwas/glob.Glob - a file path globbing type
• Registerable user defined types, which work with all API styles
• Testable commands/sub-commands
• Simple/flexible APIs for Reflection, Bind, and Context style use cases
• Generics used where it makes sense
• Fast
• Environment, YAML, TOML, HCL config loading
• Deferred default value expansion
• Standard help, version and shell completion
• Command, argument, and flag completion
• Suggestions for command names, aliases, and suggested names
• Argument validation and advanced shell completion support
• TinyGo compatible

Using

Add to a Go project in the usual way:

$ go get -u github.com/xo/ox@latest

Example

Examples are available in the package overview examples, as well as in the _examples directory.

Applications

The following applications make use of the xo/ox package for command-line parsing:

• usql - a universal command-line interface for SQL databases
• xo - a templated code generator for databases
• iv - a command-line terminal graphics image viewer
• fv - a command-line terminal graphics font viewer
• wallgrab - a Apple Aerial wallpaper downloader

About

ox aims to provide a robust and simple command-line package for the most common command-line use-cases in Go.

ox was built to streamline/simplify complexity found in the powerful (and popular!) cobra/ pflag/viper combo. ox is written in pure Go, with no non-standard package dependencies, and provides a robust, extensible type system, as well as configuration loaders for YAML, TOML, HCL that can be optionally enabled/disabled through imports.

ox avoids "magic", and has sane, sensible defaults. No interfaces, type members or other internal logic is hidden or obscured. When using ox, the user can manually build commands and flags however they see fit.

Wherever a non-standard package has been used, such as for the YAML, TOML, or HCL loaders, or for the built-in support for colors, globs, and UUIDs, the external dependencies are optional, requiring a import of a xo/ox subpackage, for example:

import (
  // base package
  "github.com/xo/ox"

  // import config loaders
  _ "github.com/xo/ox/hcl"
  _ "github.com/xo/ox/toml"
  _ "github.com/xo/ox/yaml"

  // well-known types
  _ "github.com/xo/ox/color"
  _ "github.com/xo/ox/glob"
  _ "github.com/xo/ox/uuid"
)

ox has been designed to use generics, and is built with Go 1.23+ applications in mind and works with TinyGo.

Specific design considerations of the ox package:

• Constrained "good enough" feature set, no ambition to support every use case/scenario
• No magic, sane defaults, overrideable defaults
• Functional option and interface smuggling
• Use generics, iterators and other go1.23+ features where prudent
• Work with TinyGo out of the box
• Minimal use of reflection (unless TinyGo supports it)
• Case sensitive
• Enable registration for config file loaders, types with minimal hassle
• Man page generation
• Optional support for common use-cases, via package dependencies

Other command-line packages:

• spf13/cobra + spf13/viper + spf13/pflag
• urfave/cli
• alecthomas/kong
• alecthomas/kingpin
• jessevdk/go-flags
• mow.cli
• peterbourgon/ff

Articles:

• Matt Turner, Choosing a Go CLI Library

License

xo/ox is licensed under the MIT License. ox's completion scripts are originally cribbed from the cobra project, and are made available under the Apache License.