Juniper Junos OS commands cheat sheet

Start the Junos CLI in operational mode from the shell.

Needed when you log in as root on the console, which lands in the shell.

Enter configuration mode to edit the shared candidate configuration.

The prompt changes to # with an [edit] banner. Up to 32 users can edit at once and see each other's changes.

Enter configuration mode and lock the candidate so others cannot commit.

Other users can still enter configuration mode but cannot make permanent changes while you hold the lock.

Edit a private copy of the candidate so a commit includes only your changes.

Run update in configuration mode to pull in changes other users have committed.

Move to a level of the configuration hierarchy, creating it if needed.

The [edit ...] banner shows where you are. up goes one level up and top returns to [edit].

Run an operational mode command without leaving configuration mode.

Leave configuration mode from any level without a prompt.

Plain exit moves back one level, and from the top level asks before leaving with uncommitted changes.

Add or change a statement in the candidate configuration.

Your position in the hierarchy does not change. Nothing takes effect until commit.

Remove a statement and everything under it from the candidate configuration.

Warning: All subordinate statements under the path are removed too. Live traffic is affected only after commit; rollback 0 undoes it before then.

Show uncommitted changes against the active configuration.

Lines starting with + are added and lines starting with - are removed. Run it before every commit.

Compare the candidate with a previously committed configuration.

Check the candidate configuration for errors without activating it.

Activate the candidate configuration.

Add comment "<text>" to record why, for example commit comment "Add VLAN 30". View past commits with show system commit.

Activate the candidate but roll back automatically unless you confirm in time.

The default is 10 minutes. Confirm with commit or commit check before the timer ends. Use it for remote changes that could cut off your access.

Commit and return to operational mode in one step.

Load a previously committed configuration into the candidate.

0 is the active configuration and 49 the oldest; Junos keeps the last 50 commits. Run commit to activate the one you loaded.

Discard all uncommitted changes in the candidate configuration.

Reloads the active configuration into the candidate. Committed changes are not touched.

Show the committed configuration that is running now (operational mode).

In configuration mode, show displays the candidate at the current level instead.

Show the configuration as the set commands that would recreate it.

In configuration mode use show | display set, or show | display set relative for paths from your current level.

Show only output lines that match a pattern.

Quote patterns that contain spaces. | except hides matching lines and | count counts lines.

Print the whole output without pausing at each screen.

Set the device hostname shown in the prompt.

Enclose the name in double quotes if it contains spaces.

Set the root password; you are prompted to type it twice.

Junos will not accept a commit until a root password is set. The password is stored encrypted.

Create a local admin account with full permissions.

Other built-in classes are operator, read-only and unauthorized.

Enable the SSH server for remote management.

Sync the system clock with an NTP server.

Check sync with show ntp associations and show ntp status.

Add a DNS server for name resolution.

Assign an IPv4 address to a routed interface.

Administratively shut down an interface.

Bring it back with delete interfaces <interface> disable, then commit.

Create a VLAN with a name and an 802.1Q ID.

On ELS switches every VLAN must have an ID or the commit fails.

Make a switch port an access port.

Put a port in a VLAN, by VLAN name or ID.

For a trunk, list several VLANs in brackets, for example vlan members [ STAFF VOICE ].

Make a switch port a trunk that carries several tagged VLANs.

Accept untagged data frames on a trunk and place them in this VLAN.

On ELS it goes on the physical interface, and the same VLAN must also be in the port's vlan members. Without it, untagged data frames on a trunk are dropped.

Create a Layer 3 IRB interface to route for a VLAN.

Bind the IRB interface to a VLAN so the VLAN can be routed.

Add a static route.

Static routes have a default preference of 5 and become active only when the next hop is reachable.

Add a default route.

Show active entries in the routing tables.

Add a prefix or address to see only matching routes.

Show only routes learned from one source, such as static, direct, local, ospf or bgp.

List interfaces with admin and link state, protocol family and addresses.

List VLANs with their IDs and member interfaces (ELS).

Show the MAC addresses the switch has learned, with VLAN and interface (ELS).

List neighboring devices discovered with LLDP.

Show the hostname and the Junos OS version running on the device.

Show the main system log file.

show log on its own lists the available log files.

Send a set number of ICMP echo requests.

Without count, ping runs until you press Ctrl+C. Add rapid for a single summary line, or source <address> to pick the source IP.

Show the hops packets take to reach a destination.

Show live interface statistics, updated every second.

Use monitor interface traffic for all active interfaces. Press q or Esc to quit.

Capture packet headers sent and received by the Routing Engine on an interface.

Shows control-plane traffic to and from the device, not transit traffic. Use count to stop after a number of packets.

Save the candidate configuration at the current level to a file (configuration mode).

By default the file goes in your home directory. It includes uncommitted changes.

List files on the device.

Paste configuration text and merge it into the candidate.

Press Ctrl+D on a new line to finish. Use load set terminal to paste set commands. Review with show | compare, then commit.

Replace the whole candidate configuration with a saved file.

Warning: Everything in the candidate that is not in the file is discarded, and the next commit makes that live. Check with show | compare before committing.

Save the current committed configuration as the rescue configuration.

Restore it later with rollback rescue followed by commit.

Reboot the device.

Warning: All traffic through the device stops while it restarts. Commit or discard pending changes first. EX switches wait one minute before rebooting; clear system reboot cancels a scheduled reboot.

Erase all configuration, logs and user files and reset the device to factory defaults.

Warning: Removes the configuration, log files, passwords, secrets and private keys, then reboots to the factory default configuration. Afterwards you can only log in from the console as root. Back up the configuration first.