CLI Overview

Key Features of the CLI

The CLI commands and statements follow a hierarchical organization and have a regular syntax. The CLI provides the following features to simplify CLI use:

• Consistent command names—Commands that provide the same type of function have the same name, regardless of the specific device type on which you are operating. For example, all show commands display software information and statistics, and all clear commands erase various types of system information.

• Lists and short descriptions of available commands—The CLI provides information about available commands t each level of the command hierarchy. If you type a question mark (?) at any level, you see a list of the available commands along with a short description of each. This means that if you are already familiar with Junos OS or with other routing software, you can use many of the CLI commands without referring to the documentation.

• Command completion—Command completion for command names (keywords) and for command options is available at each level of the hierarchy. To complete a command or option that you have partially typed, press the Tab key or the Spacebar. If the partially typed letters begin a string that uniquely identifies a command, the complete command name appears. Otherwise, a beep indicates that you have entered an ambiguous command, and the CLI displays possible completions. Completion also applies to other strings, such as filenames, interface names, usernames, and configuration statements.

  If you have typed the mandatory arguments for executing a command in operational mode or configuration mode, the CLI displays <[Enter]> as one of the choices when you type a question mark (?). This output indicates that you have entered the mandatory arguments and can execute the command at that level without specifying any further options. Likewise, the CLI also displays <[Enter]> when you reach a specific hierarchy level in the configuration mode and do not need to enter any more mandatory arguments or statements.

• Industry-standard technology—With FreeBSD UNIX as the kernel, a variety of UNIX utilities are available on the CLI. For example, you can:

  • Use regular expression matching to locate and to replace values and identifiers in a configuration, to filter command output, and to examine log file entries.

  • Use Emacs-based key sequences to move around on a command line and scroll through the recently executed commands and command output.

  • Store and archive Junos OS device files on a UNIX-based file system.

    Use standard UNIX conventions to specify filenames and paths.

    Exit the CLI environment and create a UNIX C shell or Bourne shell to navigate the file system, manage router processes, and so on.

CLI Command Hierarchy

CLI commands are organized in a hierarchy. Commands that perform a similar function are grouped together under the same level of the hierarchy. For example, all commands that display information about the system and the system software are under the show system command. All commands that display information about the routing table are under the show route command.

To execute a command, enter the full command name, starting at the top level of the hierarchy. For example, to display a brief view of the routes in the routing table, use the command show route brief.

Configuration Statement Hierarchy

The configuration statement hierarchy has two types of statements: Container statements, which are statements that contain other statements, and leaf statements, which do not contain other statements. All the container statements and leaf statements together form the configuration hierarchy.

The following illustration shows a part of the hierarchy tree. The protocols statement is a top-level statement at the trunk of the configuration tree. The ospf, area, and interface statements are all subordinate container statements of a higher statement; that is, they are branches of the hierarchy tree. The hello-interval statement is a leaf on the tree.

Move Among Hierarchy Levels

The following table shows the CLI commands you use to navigate the levels of the configuration statement hierarchy.

Table 1: CLI Configuration Mode Navigation Commands

Command	Description
edit hierarchy-level	Moves to an existing configuration statement hierarchy or creates a hierarchy and moves to that level.
exit	Moves up the hierarchy to the previous level where you were working. This command is, in effect, the opposite of the edit command. Alternatively, you can use the quit command. The exit command and the quit command are interchangeable.
up	Moves up the hierarchy one level at a time.
top	Moves directly to the top level of the hierarchy.