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##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
Whenever I use `ansible-vault encrypt_string`, I want to take the result and add it to a variable file, however I have to manually select the text/copy/open file for editing/paste/save the change.  This process is painful especially when you have multiple strings to encrypt as it doesn't work with the Unix way of things thus being very manual.   I thought `ansible-vault encrypt_string --output` might be something to help here, but the help documentation is confusing as it appears this is only used with `encrypt` and `decrypt` _(commands)_.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
lib/ansible/cli/vault.py

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
The only way I can see this working _without coming up with custom file descriptors or repurposing stderr for encrypted output so redirection will work_ is to add a new option that could append the resulting string to a file.
```shell
ansible-vault encrypt_string --encrypt-vault-id default --stdin-name --append vars_file.yml
Reading plaintext input from stdin. (ctrl-d to end input)
hunter22
Encryption successful
```
''' open and decrypt an existing vaulted file in an editor, that will be encrypted again when closed'''
        for f in context.CLIARGS['args']:
            self.editor.edit_file(f)
    def execute_view(self):
        ''' open, decrypt and view an existing vaulted file using a pager using the supplied vault secret '''
        for f in context.CLIARGS['args']:
            
            
            
            
            
            plaintext = self.editor.plaintext(f)
            self.pager(to_text(plaintext))
    def execute_rekey(self):
        ''' re-encrypt a vaulted file with a new secret, the previous secret is required '''
        for f in context.CLIARGS['args']:
            
            self.editor.rekey_file(f, self.new_encrypt_secret,
                                   self.new_encrypt_vault_id)
        display.display("Rekey successful", stderr=True)
def main(args=None):
    VaultCLI.cli_executor(args)
if __name__ == '__main__':
    main()