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@ -17,7 +17,8 @@ Many of the most widely used Go projects are built using Cobra including:
* [Parse (CLI)](https://parse.com/)
[![Build Status](https://travis-ci.org/spf13/cobra.svg)](https://travis-ci.org/spf13/cobra)
[![Build Status](https://travis-ci.org/spf13/cobra.svg "Travis CI status")](https://travis-ci.org/spf13/cobra)
[![CircleCI status](https://circleci.com/gh/spf13/cobra.png?circle-token=:circle-token "CircleCI status")](https://circleci.com/gh/spf13/cobra)
![cobra](https://cloud.githubusercontent.com/assets/173412/10911369/84832a8e-8212-11e5-9f82-cc96660a4794.gif)
@ -27,33 +28,33 @@ Cobra is a library providing a simple interface to create powerful modern CLI
interfaces similar to git & go tools.
Cobra is also an application that will generate your application scaffolding to rapidly
develop a Cobra based application.
develop a Cobra-based application.
Cobra provides:
* Easy sub-command based CLIs: `app server`, `app fetch`, etc.
* Fully posix compliant flags (including short & long versions)
* Nested sub commands
* Easy subcommand-based CLIs: `app server`, `app fetch`, etc.
* Fully POSIX-compliant flags (including short & long versions)
* Nested subcommands
* Global, local and cascading flags
* Easy generation of applications & commands with `cobra create appname` & `cobra add cmdname`
* Intelligent suggestions (`app srver`.. did you mean `app server`)
* Intelligent suggestions (`app srver`... did you mean `app server`?)
* Automatic help generation for commands and flags
* Automatic detailed help for `app help [command]`
* Automatic help flag recognition of `-h`, `--help`, etc.
* Automatically generated bash autocomplete for your application
* Automatically generated man pages for your application
* Command aliases so you can change things without breaking them
* The flexibilty to define your own help, usage, etc
* Optional tight integration with [viper](http://github.com/spf13/viper) for 12 factor apps
* The flexibilty to define your own help, usage, etc.
* Optional tight integration with [viper](http://github.com/spf13/viper) for 12-factor apps
Cobra has an exceptionally clean interface and simple design without needless
constructors or initialization methods.
Applications built with Cobra commands are designed to be as user friendly as
Applications built with Cobra commands are designed to be as user-friendly as
possible. Flags can be placed before or after the command (as long as a
confusing space isn’t provided). Both short and long flags can be used. A
command need not even be fully typed. The shortest unambiguous string will
suffice. Help is automatically generated and available for the application or
for a specific command using either the help command or the --help flag.
for a specific command using either the help command or the `--help` flag.
## Concepts
@ -61,9 +62,9 @@ Cobra is built on a structure of commands & flags.
**Commands** represent actions and **Flags** are modifiers for those actions.
In the following example 'server' is a command and 'port' is a flag.
In the following example, 'server' is a command, and 'port' is a flag:
hugo server --port=1313
> hugo server --port=1313
### Commands
@ -71,47 +72,51 @@ Command is the central point of the application. Each interaction that
the application supports will be contained in a Command. A command can
have children commands and optionally run an action.
In the example above 'server' is the command
In the example above, 'server' is the command.
A Command has the following structure:
type Command struct {
```go
type Command struct {
Use string // The one-line usage message.
Short string // The short description shown in the 'help' output.
Long string // The long message shown in the 'help <this-command>' output.
Run func(cmd *Command, args []string) // Run runs the command.
}
}
```
### Flags
A Flag is a way to modify the behavior of an command. Cobra supports
fully posix compliant flags as well as the go flag package.
A Flag is a way to modify the behavior of a command. Cobra supports
fully POSIX-compliant flags as well as the Go [flag package](https://golang.org/pkg/flag/).
A Cobra command can define flags that persist through to children commands
and flags that are only available to that command.
In the example above 'port' is the flag.
In the example above, 'port' is the flag.
Flag functionality is provided by the [pflag
library](https://github.com/ogier/pflag), a fork of the flag standard library
which maintains the same interface while adding posix compliance.
which maintains the same interface while adding POSIX compliance.
## Usage
Cobra works by creating a set of commands and then organizing them into a tree.
The tree defines the structure of the application.
Once each command is defined with it's corresponding flags, then the
Once each command is defined with its corresponding flags, then the
tree is assigned to the commander which is finally executed.
### Installing
Using Cobra is easy. First use go get to install the latest version
of the library.
Using Cobra is easy. First, use `go get` to install the latest version
of the library:
$ go get github.com/spf13/cobra
> go get -v github.com/spf13/cobra
Next include cobra in your application.
Next, include Cobra in your application:
import "github.com/spf13/cobra"
```go
import "github.com/spf13/cobra"
```
### Create the root command
@ -150,7 +155,9 @@ var versionCmd = &cobra.Command{
### Attach command to its parent
In this example we are attaching it to the root, but commands can be attached at any level.
HugoCmd.AddCommand(versionCmd)
```go
HugoCmd.AddCommand(versionCmd)
```
### Assign flags to a command
@ -158,8 +165,10 @@ Since the flags are defined and used in different locations, we need to
define a variable outside with the correct scope to assign the flag to
work with.
var Verbose bool
var Source string
```go
var Verbose bool
var Source string
```
There are two different approaches to assign a flag.
@ -167,34 +176,42 @@ There are two different approaches to assign a flag.
A flag can be 'persistent' meaning that this flag will be available to the
command it's assigned to as well as every command under that command. For
global flags assign a flag as a persistent flag on the root.
global flags, assign a flag as a persistent flag on the root.
HugoCmd.PersistentFlags().BoolVarP(&Verbose, "verbose", "v", false, "verbose output")
```go
HugoCmd.PersistentFlags().BoolVarP(&Verbose, "verbose", "v", false, "verbose output")
```
#### Local Flags
A flag can also be assigned locally which will only apply to that specific command.
HugoCmd.Flags().StringVarP(&Source, "source", "s", "", "Source directory to read from")
```go
HugoCmd.Flags().StringVarP(&Source, "source", "s", "", "Source directory to read from")
```
### Remove a command from its parent
Removing a command is not a common action in simple programs but it allows 3rd parties to customize an existing command tree.
Removing a command is not a common action in simple programs, but it allows 3rd parties to customize an existing command tree.
In this example, we remove the existing `VersionCmd` command of an existing root command, and we replace it by our own version.
In this example, we remove the existing `VersionCmd` command of an existing root command, and we replace it with our own version:
mainlib.RootCmd.RemoveCommand(mainlib.VersionCmd)
mainlib.RootCmd.AddCommand(versionCmd)
```go
mainlib.RootCmd.RemoveCommand(mainlib.VersionCmd)
mainlib.RootCmd.AddCommand(versionCmd)
```
### Once all commands and flags are defined, Execute the commands
Execute should be run on the root for clarity, though it can be called on any command.
HugoCmd.Execute()
```go
HugoCmd.Execute()
```
## Example
In the example below we have defined three commands. Two are at the top level
In the example below, we have defined three commands. Two are at the top level
and one (cmdTimes) is a child of one of the top commands. In this case the root
is not executable meaning that a subcommand is required. This is accomplished
by not providing a 'Run' for the 'rootCmd'.
@ -202,6 +219,7 @@ by not providing a 'Run' for the 'rootCmd'.
We have only defined one flag for a single command.
More documentation about flags is available at https://github.com/spf13/pflag
```go
package main
@ -258,56 +276,80 @@ func main() {
rootCmd.Execute()
}
```
For a more complete example of a larger application, please checkout [Hugo](http://hugo.spf13.com)
For a more complete example of a larger application, please checkout [Hugo](http://gohugo.io/).
## The Help Command
Cobra automatically adds a help command to your application when you have subcommands.
This will be called when a user runs 'app help'. Additionally help will also
support all other commands as input. Say for instance you have a command called
'create' without any additional configuration cobra will work when 'app help
This will be called when a user runs 'app help'. Additionally, help will also
support all other commands as input. Say, for instance, you have a command called
'create' without any additional configuration; Cobra will work when 'app help
create' is called. Every command will automatically have the '--help' flag added.
### Example
The following output is automatically generated by cobra. Nothing beyond the
The following output is automatically generated by Cobra. Nothing beyond the
command and flag definitions are needed.
> hugo help
A Fast and Flexible Static Site Generator built with
love by spf13 and friends in Go.
hugo is the main command, used to build your Hugo site.
Complete documentation is available at http://hugo.spf13.com
Hugo is a Fast and Flexible Static Site Generator
built with love by spf13 and friends in Go.
Complete documentation is available at http://gohugo.io/.
Usage:
hugo [flags]
hugo [command]
Available Commands:
server :: Hugo runs it's own a webserver to render the files
version :: Print the version number of Hugo
check :: Check content in the source directory
benchmark :: Benchmark hugo by building a site a number of times
help [command] :: Help about any command
server Hugo runs its own webserver to render the files
version Print the version number of Hugo
config Print the site configuration
check Check content in the source directory
benchmark Benchmark hugo by building a site a number of times.
convert Convert your content to different formats
new Create new content for your site
list Listing out various types of content
undraft Undraft changes the content's draft status from 'True' to 'False'
genautocomplete Generate shell autocompletion script for Hugo
gendoc Generate Markdown documentation for the Hugo CLI.
genman Generate man page for Hugo
import Import your site from others.
Available Flags:
-b, --base-url="": hostname (and path) to the root eg. http://spf13.com/
-D, --build-drafts=false: include content marked as draft
Flags:
-b, --baseURL="": hostname (and path) to the root, e.g. http://spf13.com/
-D, --buildDrafts[=false]: include content marked as draft
-F, --buildFuture[=false]: include content with publishdate in the future
--cacheDir="": filesystem path to cache directory. Defaults: $TMPDIR/hugo_cache/
--canonifyURLs[=false]: if true, all relative URLs will be canonicalized using baseURL
--config="": config file (default is path/config.yaml|json|toml)
-d, --destination="": filesystem path to write files to
--disableRSS[=false]: Do not build RSS files
--disableSitemap[=false]: Do not build Sitemap file
--editor="": edit new content with this editor, if provided
--ignoreCache[=false]: Ignores the cache directory for reading but still writes to it
--log[=false]: Enable Logging
--logFile="": Log File path (if set, logging enabled automatically)
--noTimes[=false]: Don't sync modification time of files
--pluralizeListTitles[=true]: Pluralize titles in lists using inflect
--preserveTaxonomyNames[=false]: Preserve taxonomy names as written ("Gérard Depardieu" vs "gerard-depardieu")
-s, --source="": filesystem path to read files relative from
--stepAnalysis=false: display memory and timing of different steps of the program
--uglyurls=false: if true, use /filename.html instead of /filename/
-v, --verbose=false: verbose output
-w, --watch=false: watch filesystem for changes and recreate as needed
Use "hugo help [command]" for more information about that command.
--stepAnalysis[=false]: display memory and timing of different steps of the program
-t, --theme="": theme to use (located in /themes/THEMENAME/)
--uglyURLs[=false]: if true, use /filename.html instead of /filename/
-v, --verbose[=false]: verbose output
--verboseLog[=false]: verbose logging
-w, --watch[=false]: watch filesystem for changes and recreate as needed
Use "hugo [command] --help" for more information about a command.
Help is just a command like any other. There is no special logic or behavior
around it. In fact you can provide your own if you want.
around it. In fact, you can provide your own if you want.
### Defining your own help
@ -330,62 +372,90 @@ func (c *Command) initHelp() {
}
```
You can provide your own command, function or template through the following methods.
You can provide your own command, function or template through the following methods:
command.SetHelpCommand(cmd *Command)
```go
command.SetHelpCommand(cmd *Command)
command.SetHelpFunc(f func(*Command, []string))
command.SetHelpFunc(f func(*Command, []string))
command.SetHelpTemplate(s string)
command.SetHelpTemplate(s string)
```
The latter two will also apply to any children commands.
## Usage
When the user provides an invalid flag or invalid command Cobra responds by
showing the user the 'usage'
When the user provides an invalid flag or invalid command, Cobra responds by
showing the user the 'usage'.
### Example
You may recognize this from the help above. That's because the default help
embeds the usage as part of it's output.
embeds the usage as part of its output.
Usage:
hugo [flags]
hugo [command]
Available Commands:
server Hugo runs it's own a webserver to render the files
server Hugo runs its own webserver to render the files
version Print the version number of Hugo
config Print the site configuration
check Check content in the source directory
benchmark Benchmark hugo by building a site a number of times
help [command] Help about any command
benchmark Benchmark hugo by building a site a number of times.
convert Convert your content to different formats
new Create new content for your site
list Listing out various types of content
undraft Undraft changes the content's draft status from 'True' to 'False'
genautocomplete Generate shell autocompletion script for Hugo
gendoc Generate Markdown documentation for the Hugo CLI.
genman Generate man page for Hugo
import Import your site from others.
Available Flags:
-b, --base-url="": hostname (and path) to the root eg. http://spf13.com/
-D, --build-drafts=false: include content marked as draft
Flags:
-b, --baseURL="": hostname (and path) to the root, e.g. http://spf13.com/
-D, --buildDrafts[=false]: include content marked as draft
-F, --buildFuture[=false]: include content with publishdate in the future
--cacheDir="": filesystem path to cache directory. Defaults: $TMPDIR/hugo_cache/
--canonifyURLs[=false]: if true, all relative URLs will be canonicalized using baseURL
--config="": config file (default is path/config.yaml|json|toml)
-d, --destination="": filesystem path to write files to
--disableRSS[=false]: Do not build RSS files
--disableSitemap[=false]: Do not build Sitemap file
--editor="": edit new content with this editor, if provided
--ignoreCache[=false]: Ignores the cache directory for reading but still writes to it
--log[=false]: Enable Logging
--logFile="": Log File path (if set, logging enabled automatically)
--noTimes[=false]: Don't sync modification time of files
--pluralizeListTitles[=true]: Pluralize titles in lists using inflect
--preserveTaxonomyNames[=false]: Preserve taxonomy names as written ("Gérard Depardieu" vs "gerard-depardieu")
-s, --source="": filesystem path to read files relative from
--stepAnalysis=false: display memory and timing of different steps of the program
--uglyurls=false: if true, use /filename.html instead of /filename/
-v, --verbose=false: verbose output
-w, --watch=false: watch filesystem for changes and recreate as needed
--stepAnalysis[=false]: display memory and timing of different steps of the program
-t, --theme="": theme to use (located in /themes/THEMENAME/)
--uglyURLs[=false]: if true, use /filename.html instead of /filename/
-v, --verbose[=false]: verbose output
--verboseLog[=false]: verbose logging
-w, --watch[=false]: watch filesystem for changes and recreate as needed
### Defining your own usage
You can provide your own usage function or template for cobra to use.
You can provide your own usage function or template for Cobra to use.
The default usage function is
The default usage function is:
return func(c *Command) error {
```go
return func(c *Command) error {
err := tmpl(c.Out(), c.UsageTemplate(), c)
return err
}
}
```
Like help the function and template are over ridable through public methods.
Like help, the function and template are overridable through public methods:
command.SetUsageFunc(f func(*Command) error)
```go
command.SetUsageFunc(f func(*Command) error)
command.SetUsageTemplate(s string)
command.SetUsageTemplate(s string)
```
## PreRun or PostRun Hooks
@ -397,7 +467,7 @@ It is possible to run functions before or after the main `Run` function of your
- `PostRun`
- `PersistentPostRun`
And example of two commands which use all of these features is below. When the subcommand in executed it will run the root command's `PersistentPreRun` but not the root command's `PersistentPostRun`
An example of two commands which use all of these features is below. When the subcommand is executed, it will run the root command's `PersistentPreRun` but not the root command's `PersistentPostRun`:
```go
package main
@ -432,7 +502,7 @@ func main() {
var subCmd = &cobra.Command{
Use: "sub [no options!]",
Short: "My sub command",
Short: "My subcommand",
PreRun: func(cmd *cobra.Command, args []string) {
fmt.Printf("Inside subCmd PreRun with args: %v\n", args)
},
@ -501,11 +571,11 @@ func main() {
## Suggestions when "unknown command" happens
Cobra will print automatic suggestions when "unknown command" errors happen. This allows Cobra to behavior similarly to the `git` command when a typo happens. For example:
Cobra will print automatic suggestions when "unknown command" errors happen. This allows Cobra to behave similarly to the `git` command when a typo happens. For example:
```
$ hugo srever
unknown command "srever" for "hugo"
Error: unknown command "srever" for "hugo"
Did you mean this?
server
@ -513,48 +583,54 @@ Did you mean this?
Run 'hugo --help' for usage.
```
Suggestions are automatic based on every subcommand registered and use an implementation of Levenshtein distance. Every registered command that matches a minimum distance of 2 (ignoring case) will be displayed as a suggestion.
Suggestions are automatic based on every subcommand registered and use an implementation of [Levenshtein distance](http://en.wikipedia.org/wiki/Levenshtein_distance). Every registered command that matches a minimum distance of 2 (ignoring case) will be displayed as a suggestion.
If you need to disable suggestions or tweak the string distance in your command, use:
command.DisableSuggestions = true
```go
command.DisableSuggestions = true
```
or
command.SuggestionsMinimumDistance = 1
```go
command.SuggestionsMinimumDistance = 1
```
You can also explicitly set names for which a given command will be suggested using the `SuggestFor` attribute. This allows suggestions for strings that are not close in terms of string distance, but makes sense in your set of commands and for some which you don't want aliases. Example:
```
$ hugo delete
unknown command "delete" for "hugo"
$ kubectl remove
Error: unknown command "remove" for "kubectl"
Did you mean this?
remove
delete
Run 'hugo --help' for usage.
Run 'kubectl help' for usage.
```
## Generating markdown formatted documentation for your command
## Generating Markdown-formatted documentation for your command
Cobra can generate a markdown formatted document based on the subcommands, flags, etc. A simple example of how to do this for your command can be found in [Markdown Docs](md_docs.md)
Cobra can generate a Markdown-formatted document based on the subcommands, flags, etc. A simple example of how to do this for your command can be found in [Markdown Docs](md_docs.md).
## Generating man pages for your command
Cobra can generate a man page based on the subcommands, flags, etc. A simple example of how to do this for your command can be found in [Man Docs](man_docs.md)
Cobra can generate a man page based on the subcommands, flags, etc. A simple example of how to do this for your command can be found in [Man Docs](man_docs.md).
## Generating bash completions for your command
Cobra can generate a bash completions file. If you add more information to your command these completions can be amazingly powerful and flexible. Read more about [Bash Completions](bash_completions.md)
Cobra can generate a bash-completion file. If you add more information to your command, these completions can be amazingly powerful and flexible. Read more about it in [Bash Completions](bash_completions.md).
## Debugging
Cobra provides a ‘DebugFlags’ method on a command which when called will print
out everything Cobra knows about the flags for each command
Cobra provides a ‘DebugFlags’ method on a command which, when called, will print
out everything Cobra knows about the flags for each command.
### Example
command.DebugFlags()
```go
command.DebugFlags()
```
## Release Notes
* **0.9.0** June 17, 2014
@ -584,7 +660,7 @@ out everything Cobra knows about the flags for each command
Libraries for extending Cobra:
* [cmdns](https://github.com/gosuri/cmdns): Enables name spacing a command's immediate children. It provides an alternative way to structure sub commands, similar to `heroku apps:create` and `ovrclk clusters:launch`.
* [cmdns](https://github.com/gosuri/cmdns): Enables name spacing a command's immediate children. It provides an alternative way to structure subcommands, similar to `heroku apps:create` and `ovrclk clusters:launch`.
## ToDo
* Launch proper documentation site
@ -601,7 +677,9 @@ Libraries for extending Cobra:
Names in no particular order:
* [spf13](https://github.com/spf13)
* [spf13](https://github.com/spf13),
[eparis](https://github.com/eparis),
[bep](https://github.com/bep), ...
## License