196 lines
4.3 KiB
Markdown
196 lines
4.3 KiB
Markdown
[](https://travis-ci.org/codegangsta/cli)
|
|
|
|
# cli.go
|
|
cli.go is simple, fast, and fun package for building command line apps in Go. The goal is to enable developers to write fast and distributable command line applications in an expressive way.
|
|
|
|
You can view the API docs here:
|
|
http://godoc.org/github.com/codegangsta/cli
|
|
|
|
## Overview
|
|
Command line apps are usually so tiny that there is absolutely no reason why your code should *not* be self-documenting. Things like generating help text and parsing command flags/options should not hinder productivity when writing a command line app.
|
|
|
|
This is where cli.go comes into play. cli.go makes command line programming fun, organized, and expressive!
|
|
|
|
## Installation
|
|
Make sure you have the a working Go environment (go 1.1 is *required*). [See the install instructions](http://golang.org/doc/install.html).
|
|
|
|
To install cli.go, simply run:
|
|
```
|
|
$ go get github.com/codegangsta/cli
|
|
```
|
|
|
|
Make sure your PATH includes to the `$GOPATH/bin` directory so your commands can be easily used:
|
|
```
|
|
export PATH=$PATH:$GOPATH/bin
|
|
```
|
|
|
|
## Getting Started
|
|
One of the philosophies behind cli.go is that an API should be playful and full of discovery. So a cli.go app can be as little as one line of code in `main()`.
|
|
|
|
``` go
|
|
package main
|
|
|
|
import (
|
|
"os"
|
|
"github.com/codegangsta/cli"
|
|
)
|
|
|
|
func main() {
|
|
cli.NewApp().Run(os.Args)
|
|
}
|
|
```
|
|
|
|
This app will run and show help text, but is not very useful. Let's give an action to execute and some help documentation:
|
|
|
|
``` go
|
|
package main
|
|
|
|
import (
|
|
"os"
|
|
"github.com/codegangsta/cli"
|
|
)
|
|
|
|
func main() {
|
|
app := cli.NewApp()
|
|
app.Name = "boom"
|
|
app.Usage = "make an explosive entrance"
|
|
app.Action = func(c *cli.Context) {
|
|
println("boom! I say!")
|
|
}
|
|
|
|
app.Run(os.Args)
|
|
}
|
|
```
|
|
|
|
Running this already gives you a ton of functionality, plus support for things like subcommands and flags, which are covered below.
|
|
|
|
## Example
|
|
|
|
Being a programmer can be a lonely job. Thankfully by the power of automation that is not the case! Let's create a greeter app to fend off our demons of loneliness!
|
|
|
|
``` go
|
|
/* greet.go */
|
|
package main
|
|
|
|
import (
|
|
"os"
|
|
"github.com/codegangsta/cli"
|
|
)
|
|
|
|
func main() {
|
|
app := cli.NewApp()
|
|
app.Name = "greet"
|
|
app.Usage = "fight the loneliness!"
|
|
app.Action = func(c *cli.Context) {
|
|
println("Hello friend!")
|
|
}
|
|
|
|
app.Run(os.Args)
|
|
}
|
|
```
|
|
|
|
Install our command to the `$GOPATH/bin` directory:
|
|
|
|
```
|
|
$ go install
|
|
```
|
|
|
|
Finally run our new command:
|
|
|
|
```
|
|
$ greet
|
|
Hello friend!
|
|
```
|
|
|
|
cli.go also generates some bitchass help text:
|
|
```
|
|
$ greet help
|
|
NAME:
|
|
greet - fight the loneliness!
|
|
|
|
USAGE:
|
|
greet [global options] command [command options] [arguments...]
|
|
|
|
VERSION:
|
|
0.0.0
|
|
|
|
COMMANDS:
|
|
help, h Shows a list of commands or help for one command
|
|
|
|
GLOBAL OPTIONS
|
|
--version Shows version information
|
|
```
|
|
|
|
### Arguments
|
|
You can lookup arguments by calling the `Args` function on cli.Context.
|
|
|
|
``` go
|
|
...
|
|
app.Action = func(c *cli.Context) {
|
|
println("Hello", c.Args()[0])
|
|
}
|
|
...
|
|
```
|
|
|
|
### Flags
|
|
Setting and querying flags is simple.
|
|
``` go
|
|
...
|
|
app.Flags = []cli.Flag {
|
|
cli.StringFlag{"lang", "english", "language for the greeting"},
|
|
}
|
|
app.Action = func(c *cli.Context) {
|
|
name := "someone"
|
|
if len(c.Args()) > 0 {
|
|
name = c.Args()[0]
|
|
}
|
|
if c.String("lang") == "spanish" {
|
|
println("Hola", name)
|
|
} else {
|
|
println("Hello", name)
|
|
}
|
|
}
|
|
...
|
|
```
|
|
|
|
#### Alternate Names
|
|
|
|
You can set alternate (or short) names for flags by providing a comma-delimited list for the Name. e.g.
|
|
|
|
``` go
|
|
app.Flags = []cli.Flag {
|
|
cli.StringFlag{"lang, l", "english", "language for the greeting"},
|
|
}
|
|
```
|
|
|
|
That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error.
|
|
|
|
### Subcommands
|
|
|
|
Subcommands can be defined for a more git-like command line app.
|
|
```go
|
|
...
|
|
app.Commands = []cli.Command{
|
|
{
|
|
Name: "add",
|
|
ShortName: "a",
|
|
Usage: "add a task to the list",
|
|
Action: func(c *cli.Context) {
|
|
println("added task: ", c.FirstArg())
|
|
},
|
|
},
|
|
{
|
|
Name: "complete",
|
|
ShortName: "c",
|
|
Usage: "complete a task on the list",
|
|
Action: func(c *cli.Context) {
|
|
println("completed task: ", c.FirstArg())
|
|
},
|
|
},
|
|
}
|
|
...
|
|
```
|
|
|
|
## About
|
|
cli.go is written by none other than the [Code Gangsta](http://codegangsta.io)
|