A system, method and computer-readable medium for adapting command line output message streams in a virtualized command line interface (CLI) environment. In accordance with the method of the present invention, a virtualized CLI command is entered and executed. The virtualized CLI command encapsulates a guest operating system command having an associated standard output message. In response to executing the virtualized CLI command, the standard output message is piped to an output message file. Within the standard output message file, a structured array is used to search the standard output message for matches between strings within the standard output message and one or more specified message strings identified in the structured array. In response to finding a match between the specified message strings and the strings within the standard output message, the specified message string within the standard output message is replaced with a replacement message string.