cocoapods Mac command not found: pod解決策

$ sudo gem install cocoapods
$ pod setup
-bash: pod: command not found

こうなった方のための解決策
```
$ rbenv rehash
$ pod
Usage:

$ pod COMMAND

  CocoaPods, the Cocoa library package manager.

Commands:

+ cache      Manipulate the CocoaPods cache
+ init       Generate a Podfile for the current directory.
+ install    Install project dependencies to Podfile.lock versions
+ ipc        Inter-process communication
+ lib        Develop pods
+ list       List pods
+ outdated   Show outdated project dependencies
+ plugins    Show available CocoaPods plugins
+ repo       Manage spec-repositories
+ search     Search for pods.
+ setup      Setup the CocoaPods environment
+ spec       Manage pod specs
+ trunk      Interact with the CocoaPods API (e.g. publishing new specs)
+ try        Try a Pod!
+ update     Update outdated project dependencies and create new Podfile.lock

Options:

--silent     Show nothing
--version    Show the version of the tool
--verbose    Show more debugging information
--no-ansi    Show output without ANSI codes
--help       Show help banner of specified command

以上。