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Merge pull request #440 from urfave/more-v1-examples

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Enable more examples as runnable in README
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Dan Buch 2016-06-01 09:49:21 -04:00
commit ddb6f44179
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README.md
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@ -13,13 +13,19 @@
`github.com/codegangsta/cli` -- Github will automatically redirect requests
to this repository, but we recommend updating your references for clarity.
cli is a 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.
cli is a 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.
## 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.
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 comes into play.** cli makes command line programming fun, organized, and expressive!
**This is where cli comes into play.** cli makes command line programming fun,
organized, and expressive!
## Installation
@ -33,7 +39,8 @@ To install cli, simply run:
$ go get github.com/urfave/cli
```
Make sure your `PATH` includes to the `$GOPATH/bin` directory so your commands can be easily used:
Make sure your `PATH` includes to the `$GOPATH/bin` directory so your commands
can be easily used:
```
export PATH=$PATH:$GOPATH/bin
```
@ -86,13 +93,19 @@ import (
## Getting Started
One of the philosophies behind cli is that an API should be playful and full of discovery. So a cli app can be as little as one line of code in `main()`.
One of the philosophies behind cli is that an API should be playful and full of
discovery. So a cli app can be as little as one line of code in `main()`.
<!-- {
"args": ["&#45;&#45;help"],
"output": "A new cli application"
} -->
``` go
package main
import (
"os"
"github.com/urfave/cli"
)
@ -101,7 +114,8 @@ func main() {
}
```
This app will run and show help text, but is not very useful. Let's give an action to execute and some help documentation:
This app will run and show help text, but is not very useful. Let's give an
action to execute and some help documentation:
<!-- {
"output": "boom! I say!"
@ -129,13 +143,17 @@ func main() {
}
```
Running this already gives you a ton of functionality, plus support for things like subcommands and flags, which are covered below.
Running this already gives you a ton of functionality, plus support for things
like subcommands and flags, which are covered below.
## Example
## Examples
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!
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!
Start by creating a directory named `greet`, and within it, add a file, `greet.go` with the following code in it:
Start by creating a directory named `greet`, and within it, add a file,
`greet.go` with the following code in it:
<!-- {
"output": "Hello friend!"
@ -198,23 +216,53 @@ GLOBAL OPTIONS
### Arguments
You can lookup arguments by calling the `Args` function on `cli.Context`.
You can lookup arguments by calling the `Args` function on `cli.Context`, e.g.:
<!-- {
"output": "Hello \""
} -->
``` go
...
package main
import (
"fmt"
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Action = func(c *cli.Context) error {
fmt.Println("Hello", c.Args()[0])
fmt.Printf("Hello %q", c.Args().Get(0))
return nil
}
...
app.Run(os.Args)
}
```
### Flags
Setting and querying flags is simple.
<!-- {
"output": "Hello Nefertiti"
} -->
``` go
...
package main
import (
"fmt"
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Flags = []cli.Flag {
cli.StringFlag{
Name: "lang",
@ -222,10 +270,11 @@ app.Flags = []cli.Flag {
Usage: "language for the greeting",
},
}
app.Action = func(c *cli.Context) error {
name := "someone"
name := "Nefertiti"
if c.NArg() > 0 {
name = c.Args()[0]
name = c.Args().Get(0)
}
if c.String("lang") == "spanish" {
fmt.Println("Hola", name)
@ -234,14 +283,32 @@ app.Action = func(c *cli.Context) error {
}
return nil
}
...
app.Run(os.Args)
}
```
You can also set a destination variable for a flag, to which the content will be scanned.
You can also set a destination variable for a flag, to which the content will be
scanned.
<!-- {
"output": "Hello someone"
} -->
``` go
...
package main
import (
"os"
"fmt"
"github.com/urfave/cli"
)
func main() {
var language string
app := cli.NewApp()
app.Flags = []cli.Flag {
cli.StringFlag{
Name: "lang",
@ -250,6 +317,7 @@ app.Flags = []cli.Flag {
Destination: &language,
},
}
app.Action = func(c *cli.Context) error {
name := "someone"
if c.NArg() > 0 {
@ -262,22 +330,44 @@ app.Action = func(c *cli.Context) error {
}
return nil
}
...
app.Run(os.Args)
}
```
See full list of flags at http://godoc.org/github.com/urfave/cli
#### Placeholder Values
Sometimes it's useful to specify a flag's value within the usage string itself. Such placeholders are
indicated with back quotes.
Sometimes it's useful to specify a flag's value within the usage string itself.
Such placeholders are indicated with back quotes.
For example this:
<!-- {
"args": ["&#45;&#45;help"],
"output": "&#45;&#45;config FILE, &#45;c FILE"
} -->
```go
package main
import (
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Flags = []cli.Flag{
cli.StringFlag{
Name: "config, c",
Usage: "Load configuration from `FILE`",
},
}
app.Run(os.Args)
}
```
@ -287,13 +377,30 @@ Will result in help output like:
--config FILE, -c FILE Load configuration from FILE
```
Note that only the first placeholder is used. Subsequent back-quoted words will be left as-is.
Note that only the first placeholder is used. Subsequent back-quoted words will
be left as-is.
#### Alternate Names
You can set alternate (or short) names for flags by providing a comma-delimited list for the `Name`. e.g.
You can set alternate (or short) names for flags by providing a comma-delimited
list for the `Name`. e.g.
<!-- {
"args": ["&#45;&#45;help"],
"output": "&#45;&#45;lang value, &#45;l value.*language for the greeting.*default: \"english\""
} -->
``` go
package main
import (
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Flags = []cli.Flag {
cli.StringFlag{
Name: "lang, l",
@ -301,15 +408,35 @@ app.Flags = []cli.Flag {
Usage: "language for the greeting",
},
}
app.Run(os.Args)
}
```
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.
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.
#### Values from the Environment
You can also have the default value set from the environment via `EnvVar`. e.g.
<!-- {
"args": ["&#45;&#45;help"],
"output": "language for the greeting.*APP_LANG"
} -->
``` go
package main
import (
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Flags = []cli.Flag {
cli.StringFlag{
Name: "lang, l",
@ -318,11 +445,30 @@ app.Flags = []cli.Flag {
EnvVar: "APP_LANG",
},
}
app.Run(os.Args)
}
```
The `EnvVar` may also be given as a comma-delimited "cascade", where the first environment variable that resolves is used as the default.
The `EnvVar` may also be given as a comma-delimited "cascade", where the first
environment variable that resolves is used as the default.
<!-- {
"args": ["&#45;&#45;help"],
"output": "language for the greeting.*LEGACY_COMPAT_LANG.*APP_LANG.*LANG"
} -->
``` go
package main
import (
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Flags = []cli.Flag {
cli.StringFlag{
Name: "lang, l",
@ -331,57 +477,98 @@ app.Flags = []cli.Flag {
EnvVar: "LEGACY_COMPAT_LANG,APP_LANG,LANG",
},
}
app.Run(os.Args)
}
```
#### Values from alternate input sources (YAML and others)
There is a separate package altsrc that adds support for getting flag values from other input sources like YAML.
There is a separate package altsrc that adds support for getting flag values
from other input sources like YAML.
In order to get values for a flag from an alternate input source the following code would be added to wrap an existing cli.Flag like below:
In order to get values for a flag from an alternate input source the following
code would be added to wrap an existing cli.Flag like below:
``` go
altsrc.NewIntFlag(cli.IntFlag{Name: "test"})
```
Initialization must also occur for these flags. Below is an example initializing getting data from a yaml file below.
Initialization must also occur for these flags. Below is an example initializing
getting data from a yaml file below.
``` go
command.Before = altsrc.InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
```
The code above will use the "load" string as a flag name to get the file name of a yaml file from the cli.Context.
It will then use that file name to initialize the yaml input source for any flags that are defined on that command.
As a note the "load" flag used would also have to be defined on the command flags in order for this code snipped to work.
The code above will use the "load" string as a flag name to get the file name of
a yaml file from the cli.Context. It will then use that file name to initialize
the yaml input source for any flags that are defined on that command. As a note
the "load" flag used would also have to be defined on the command flags in order
for this code snipped to work.
Currently only YAML files are supported but developers can add support for other input sources by implementing the
altsrc.InputSourceContext for their given sources.
Currently only YAML files are supported but developers can add support for other
input sources by implementing the altsrc.InputSourceContext for their given
sources.
Here is a more complete sample of a command using YAML support:
<!-- {
"args": ["test-cmd", "&#45;&#45;help"],
"output": "&#45&#45;test value.*default: 0"
} -->
``` go
command := &cli.Command{
Name: "test-cmd",
Aliases: []string{"tc"},
Usage: "this is for testing",
Description: "testing",
Action: func(c *cli.Context) error {
// Action to run
return nil
},
Flags: []cli.Flag{
NewIntFlag(cli.IntFlag{Name: "test"}),
cli.StringFlag{Name: "load"}},
package notmain
import (
"fmt"
"os"
"github.com/urfave/cli"
"github.com/urfave/cli/altsrc"
)
func main() {
app := cli.NewApp()
flags := []cli.Flag{
altsrc.NewIntFlag(cli.IntFlag{Name: "test"}),
cli.StringFlag{Name: "load"},
}
app.Action = func(c *cli.Context) error {
fmt.Println("yaml ist rad")
return nil
}
app.Before = altsrc.InitInputSourceWithContext(flags, altsrc.NewYamlSourceFromFlagFunc("load"))
app.Flags = flags
app.Run(os.Args)
}
command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
err := command.Run(c)
```
### Subcommands
Subcommands can be defined for a more git-like command line app.
<!-- {
"args": ["template", "add"],
"output": "new task template: .+"
} -->
```go
...
package main
import (
"fmt"
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Commands = []cli.Command{
{
Name: "add",
@ -403,7 +590,7 @@ app.Commands = []cli.Command{
},
{
Name: "template",
Aliases: []string{"r"},
Aliases: []string{"t"},
Usage: "options for task templates",
Subcommands: []cli.Command{
{
@ -425,7 +612,9 @@ app.Commands = []cli.Command{
},
},
}
...
app.Run(os.Args)
}
```
### Subcommands categories
@ -437,7 +626,17 @@ output.
E.g.
```go
...
package main
import (
"os"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Commands = []cli.Command{
{
Name: "noop",
@ -451,20 +650,20 @@ E.g.
Category: "template",
},
}
...
app.Run(os.Args)
}
```
Will include:
```
...
COMMANDS:
noop
Template actions:
add
remove
...
```
### Exit code
@ -509,9 +708,23 @@ flag on the `App` object. By default, this setting will only auto-complete to
show an app's subcommands, but you can write your own completion methods for
the App or its subcommands.
<!-- {
"args": ["complete", "&#45;&#45;generate&#45;bash&#45;completion"],
"output": "laundry"
} -->
``` go
...
var tasks = []string{"cook", "clean", "laundry", "eat", "sleep", "code"}
package main
import (
"fmt"
"os"
"github.com/urfave/cli"
)
func main() {
tasks := []string{"cook", "clean", "laundry", "eat", "sleep", "code"}
app := cli.NewApp()
app.EnableBashCompletion = true
app.Commands = []cli.Command{
@ -532,9 +745,11 @@ app.Commands = []cli.Command{
fmt.Println(t)
}
},
},
}
app.Run(os.Args)
}
...
```
#### To Enable