1-8 CHAPTER 1: USING THE COMMAND L INE INTERFACE (CLI)Command LanguageStructureThe CLI command language creates, manages, displays, and removes systementities that describe system and network connections and processes. Configuredentities are stored in tables such as the IP Routing Table.Some common entities are: Network - defines local and remote networks, network connections, hostsand routers User - describes connection parameters, for operation and authorization Filter - can be applied to interfaces, connections, and users to control accessthrough the system Interface - describes physical devices; for example, ports Syslog Hosts - receives system messages DNS Servers - translates IP addresses to and from host names Route - describes a path through the network to another system/networkTable entries are created with an ADD command, and removed with a DELETEcommand. The ADD command specifies the most important parameters of theentry. Additional parameters are usually specified with the SET command, which isalso used to change configured parameters.SHOW commands display detailed information about a specific table entry or aset of scalars (non-table items). For example, show ip settings displayssystem-wide IP information. SHOW ALL commands display information. Theshow all commands display all parameters for all entries in tables associated withparticular commands.The order of items in a table is usually not relevant, nor is it inherent in the type ofentity. Sometimes the order is relevant, though, and you must specify a preferencevalue in the ADD command, indicating where this item belongs in the table. Forexample, add dns server preference 1 assigns a priority of 1 tothis DNS server. The DNS server with the highest preference number will be usedfirst.Command Features The command language has several built-in features that make it easier to use.When abbreviating commands, it’s sometimes difficult to remember commandsand their syntax. Using command completion and positional help aids in joggingyour memory of the commands and their parameters, while you are typing in acommand string.Command Line Edit Command line edit allows non-destructive cursor movements on a commandalready typed. The Command line editing commands are listed in the followingtable.(Ctrl b) or left arrow go back one character(Ctrl f) or right arrow go forward one character(Esc b) go back one word(Esc f) go forward one word(Ctrl a) go to beginning of command