31 Days Before Your CCNA Exam

48 31 Days Before Your CCNA ExamUsing the Help FacilityCisco IOS has extensive command-line input help facilities, including context-sensitive help. Thefollowing summarizes the two types of help available:■■Word help: Enter a character sequence of an incomplete command immediately followed by aquestion mark (sh?) to get a list of available commands that start with the character sequence.Command syntax help: Enter the ? command to get command syntax help to see all theavailable arguments to complete a command (show ?). IOS then displays a list of availableargumentsAs part of the help facility, IOS displays console error messages when incorrect command syntaxis entered. Table 27-1 shows sample error messages, what they mean, and how to get help whenthey are displayed.Table 27-1Console Error MessagesExample Error Meaning How to Get HelpMessageswitch#cl You did not enter enough Reenter the command followed by a% Ambiguous characters for your device to question mark (?), without a spacecommand: “cl” recognize the command. between the command and the questionmark. The possible keywords that you canenter with the command are displayed.switch#clock You did not enter all the Reenter the command followed by a% Incomplete command. keywords or values required question mark (?), with a space betweenby this command.the command and the question mark.switch#clock ste You entered the command Enter a question mark (?) to display all^ incorrectly. The caret (^) the available commands or parameters.% Invalid input detected marks the point of the error.at ‘^’ marker.CLI Navigation and Editing ShortcutsTable 27-2 summarizes the shortcuts for navigating and editing commands in CLI. Although notspecifically tested on the CCNA exam, these shortcuts may save you time when using the simulatorduring the exam.Table 27-2Hot Keys and ShortcutsKeyboard CommandWhat HappensNavigation Key SequencesUp arrow or Ctrl-PDown arrow or Ctrl-NLeft arrow or Ctrl-BThis displays the most recently used command. If you press it again, the nextmost recent command appears, until the history buffer is exhausted. (The Pstands for previous.)If you have gone too far back into the history buffer, these keys take you forwardto the more recently entered commands. (The N stands for next.)This moves the cursor backward in the currently displayed command withoutdeleting characters. (The B stands for back.)