cmus:tldr:c549b

The command ":add ${filename_or_directory}" is not a standard command and its purpose or function would depend on the specific context or software in which it is used. In general, however, we can infer that the command is attempting to add or include a file or directory specified by the "${filename_or_directory}" placeholder into a certain system, project, or version control repository. For example, if this command is used in a version control system like Git, it may be trying to add a file or directory to the repository's staging area, indicating that it should be included in the next commit. Without more information about the specific software or context in which this command is being used, it is difficult to provide a more precise explanation.