Clarify shell requirement. Fixes #1870

README.md

@@ -88,6 +88,10 @@ Likewise, your server(s) will likely need supporting software installed before y
 
 Capistrano is designed to deploy using a single, non-privileged SSH user, using a *non-interactive* SSH session. If your deployment requires `sudo`, interactive prompts, authenticating as one user but running commands as another, you can probably accomplish this with Capistrano, but it may be difficult. Your automated deployments will be much smoother if you can avoid such requirements.
 
+#### Shells
+
+Capistrano 3 expects a POSIX shell like Bash or Sh. Shells like tcsh, csh, and such may work, but probably will not.
+
 ## Quick start
 
 ### Requirements

docs/documentation/upgrading/index.markdown

@@ -136,3 +136,7 @@ Capistrano 3 now runs the `deploy:cleanup` task as part of the standard deploy w
 ```ruby
 set :keep_releases, 10
 ```
+
+#### POSIX Shell
+
+Capistrano 3 expects a POSIX shell like Bash or Sh. Shells like tcsh, csh, and such may work, but probably will not.