Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
Tweet: They are building a shell command on a server, combining that with user input, and then executing that in a shell on the client. #shudder
This tweet contains emotions: 
fear, joy