All Juniper devices run the Junos operating system. Like any network operating system, this includes a CLI (SSH, Telnet), web interface, and automation options.
Junos is based on either FreeBSD, or a customised version of Linux, depending on the Junos version.
The Junos CLU has two modes; Operational, which has the ‘>’ character as the prompt, and Configuration, which has the ‘#’ as the prompt.
The configuration itself is organised into a hierarchy. This is a tree structure, which in a sense is like a file system containing files. All configuration items are grouped into areas.
This configuration method may appear intimidating at first, as it looks a bit like a programming language. However, it’s really not difficult.
Config groups are contained within curly braces. Configuration items end with a semi-colon.
We can navigate around the hierarchy using commands like edit, up, and top.
As with most CLI’s, we have options like ‘?’ to show us commands, tab completion for commands and variables, and space complete for commands.
Changes are not applied immediately. They need to be committed.
|configure||operational||Enter configuration mode|
|help||operational||Bring up the help menu|
|help reference||operational||Lookup a command|
|help apropos||operational||Search for commands|
|help tip cli||operational||Get tips|
|help topic||operational||Get information on features and configuration tasks|
|set cli complete-on-space off||operational||Disable space complete|
|start shell||operational||Enter the FreeBSD/Linux Shell|
|exit||shell||Exit the shell|
|show configuration||operational||Show the configuration|
|show||configuration||Show the configuration|
|| match||either||Filter output for this text|
|| except||either||Filter output (remove lines with this text)|
|| No-more||either||Do not paginate output|
|| find VALUE
||either||Start where a match is found (like ‘begin’ in IOS)|
|| resolve||either||Convert IP’s to names|
|| trim||either||Trim columns from each line|
|| match “val-1|val-2|val-3”||either||Perform an OR search within match|
|run||configuration||Run an operational mode command from configuration mode|
|edit||configuration||Move around the configuration hierarchy|
|up||configuration||Move up a hierarchy level|
|top||configuration||Move to the top of the hierarchy|
|Set cli screen-length
||operational||Set cli screen-length|
|Set cli screen width||operational||Set cli screen width|
Ctrl-U erases the entire command you’ve been typing
Ctrl-W erases word by word
Ctrl-A moves to the start of the line
Ctrl-E moves to the end
Alt-B move back one word
Alt-F move forward one word
Ctrl-K Delete from the cursor to the end of the line
Ctrl-L Redraw the current line
Ctrl-P / N Repeat previous or next command in the history