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https://github.com/spf13/cobra
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51 lines
1.5 KiB
Markdown
51 lines
1.5 KiB
Markdown
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---
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weight: 2
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---
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# Concepts
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Cobra is built on a structure of commands, arguments & flags.
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**Commands** represent actions, **Args** are things and **Flags** are modifiers for those actions.
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The best applications read like sentences when used, and as a result, users
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intuitively know how to interact with them.
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The pattern to follow is
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`APPNAME VERB NOUN --ADJECTIVE.`
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or
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`APPNAME COMMAND ARG --FLAG`
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A few good real world examples may better illustrate this point.
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In the following example, 'server' is a command, and 'port' is a flag:
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hugo server --port=1313
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In this command we are telling Git to clone the url bare.
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git clone URL --bare
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## Commands
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Command is the central point of the application. Each interaction that
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the application supports will be contained in a Command. A command can
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have children commands and optionally run an action.
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In the example above, 'server' is the command.
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[More about cobra.Command](https://godoc.org/github.com/spf13/cobra#Command)
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## Flags
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A flag is a way to modify the behavior of a command. Cobra supports
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fully POSIX-compliant flags as well as the Go [flag package](https://golang.org/pkg/flag/).
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A Cobra command can define flags that persist through to children commands
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and flags that are only available to that command.
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In the example above, 'port' is the flag.
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Flag functionality is provided by the [pflag
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library](https://github.com/spf13/pflag), a fork of the flag standard library
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which maintains the same interface while adding POSIX compliance.
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