Task: Assess the emotional content of the tweet and classify it as either 'neutral or no emotion' or as one or more of the given emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best represent 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