Online Help in the CLI

Getting Help About Commands

CLI commands and options can vary by platform and software release. Each level of the CLI command hierarchy provides information about available commands. You can type a question mark (?) to get context-relevant help about commands.

• If you type the question mark at the command-line prompt, the CLI lists the available commands and options. For example, to view a list of top-level operational mode commands, this is the result:

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  user@host> ?
  Possible completions:
  clear       Clear information in the system
  configure   Manipulate software configuration information
  file        Perform file operations
  help        Provide help information
  mtrace      Trace mtrace packets from source to receiver.
  monitor     Real-time debugging
  ping        Ping a remote target
  quit        Exit the management session
  request     Make system-level requests
  restart     Restart a software process
  set         Set CLI properties, date, time, craft display text
  show        Show information about the system
  ssh         Open a secure shell to another host
  start       Start a software process
  telnet      Telnet to another host
  test        Diagnostic debugging commands
  traceroute  Trace the route to a remote host
  user@host>

• If you type the question mark after entering the complete name of a command or command option, the CLI lists the available commands and options and then re-displays the command names and options you typed.

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  user@host> clear ? 
  Possible completions:
  arp 	      Clear address-resolution information
  bgp          Clear BGP information
  chassis      Clear chassis information
  firewall     Clear firewall counters
  igmp         Clear IGMP information
  interfaces   Clear interface information
  ilmi         Clear ILMI statistics information
  isis         Clear IS-IS information
  ldp          Clear LDP information
  log          Clear contents of a log file
  mpls         Clear MPLS information
  msdp         Clear MSDP information
  multicast    Clear Multicast information
  ospf         Clear OSPF information
  pim          Clear PIM information
  rip          Clear RIP information
  route        Clear routing table information
  rsvp         Clear RSVP information
  snmp         Clear SNMP information
  system       Clear system status
  vrrp         Clear VRRP statistics information
  user@host> clear

• If you type the question mark in the middle of a command name, the CLI lists possible command completions that match the letters you have entered so far. It then re-displays the letters that you typed. For example, to list all operational mode commands that start with the letter c, type the following:

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  user@host> c?
  Possible completions:
  clear      Clear information in the system
  configure  Manipulate software configuration information
  user@host> c

• For introductory information on using the question mark or the help command, you can also type help and press Enter:

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  user@host> help

Getting Help About a String in a Statement or Command

You can use the help command to display help about a text string contained in a statement or command name:

help apropos string 

string is a text string about which you want to get help. Use the string to match statement or command names as well as to match the help strings that are displayed for the statements or commands.

If the string contains spaces, enclose it in quotation marks (" "). You can also specify a regular expression for the string, using standard UNIX-style regular expression syntax.

For statements or commands that need input data type as STRING, the supported characters set is as follows:

• Any printable ASCII characters

• For characters with space, enclose it in double-quotes.

• To have double-quote as the input, it should be escaped with ‘\’.

  Note:

  No escape characters are supported in a string other than to escape from double quotes.

• The range of supported characters for attributes is 0 through 65499 characters.

• The range of supported characters for string type identifiers is 1 through 255 characters.

In configuration mode, this command displays statement names and help text that match the string specified. In operational mode, this command displays command names and help text that match the string specified.

Getting Help About Configuration Statements

You can display help based on text contained in a statement name using the help topic and help reference commands:

help topic word
help reference statement-name

The help topic command displays usage guidelines for the statement based on information that appears in the Junos OS configuration guides. The help reference command displays summary information about the statement based on the summary descriptions that appear in the Junos OS configuration guides.

Getting Help About System Log Messages

You can display help based on a system log tag using the help syslog command:

help syslog syslog-tag

The help syslog command displays the contents of a system log message.

Help for Omitted Statements

If you have omitted a required statement at a specific hierarchy level, when you attempt to move from that hierarchy level or when you issue the show command in configuration mode, a message indicates which statement is missing. For example:

[edit protocols pim interface so-0/0/0]
user@host# top
Warning: missing mandatory statement: 'mode'
[edit]
user@host# show
protocols {
    pim {
        interface so-0/0/0 {
            priority 4;
            version 2;
            # Warning: missing mandatory statement(s): 'mode'
        }
    }
}

Using CLI Command Completion

The Junos OS CLI provides you a command completion option that enables the operating system to recognize commands and options based on the initial few letters you typed. That is, you do not always have to remember or type the full command or option name for the CLI to recognize it.

• To display all possible command or option completions, type the partial command followed immediately by a question mark.

• To complete a command or option that you have partially typed, press Tab or Space. If the partially typed letters begin a string that uniquely identifies a command, the complete command name appears. Otherwise, a prompt indicates that you have entered an ambiguous command, and the possible completions display.

Command completion also applies to other strings, such as filenames, interface names, and usernames. To display all possible values, type a partial string followed immediately by a question mark. To complete a string, press Tab.

Using Command Completion in Configuration Mode

The CLI command completion functions also apply to the commands in configuration mode and to configuration statements. Specifically, to display all possible commands or statements, type the partial string followed immediately by a question mark. To complete a command or statement that you have partially typed, press Tab or Space.

Displaying Tips About CLI Commands

To get tips about CLI commands, issue the help tip cli command. Each time you enter the command, a new tip appears. For example:

user@host> help tip cli
Junos tip:
Use 'request system software validate' to validate the incoming software
against the current configuration without impacting the running system.
user@host> help tip cli 
Junos tip:
Use 'commit and-quit' to exit configuration mode after the commit has
succeeded. If the commit fails, you are left in configuration mode.

You can also enter help tip cli number to associate a tip with a number. This enables you to recall the tip later. For example:

user@host> help tip cli 10
JUNOS tip:
Use '#' in the beginning of a line in command scripts to cause the
rest of the line to be ignored.

user@host> help tip cli       
JUNOS tip:
Use the 'apply-groups' statement at any level of the configuration
hierarchy to inherit configuration statements from a configuration group.

user@host>