Using the console

Available commands

To see a list of the available commands in the console, you can use the help:

karaf@root()> help
COMMANDS
bundle
bundle:capabilities               Displays OSGi capabilities of a given bundles.
bundle:classes                    Displays a list of classes contained in the bundle
...

You have the list of all commands with a short description.

You can use the tab key to get a quick list of all commands:

karaf@root()> Display all 280 possibilities? (y or n)
...

Subshell and completion mode

The commands have a scope and a name. For instance, the command feature:list has feature as scope, and list as name.

Karaf "groups" the commands by scope. Each scope form a subshell.

You can directly execute a command with its full qualified name (scope:name):

karaf@root()> feature:list
...

or enter in a subshell and type the command contextual to the subshell:

karaf@root()> feature
karaf@root(feature)> list

You can note that you enter in a subshell directly by typing the subshell name (here feature). You can "switch" directly from a subshell to another:

karaf@root()> feature
karaf@root(feature)> bundle
karaf@root(bundle)>

The prompt displays the current subshell between ().

The exit command goes to the parent subshell:

karaf@root()> feature
karaf@root(feature)> exit
karaf@root()>

The completion mode defines the behaviour of the tab key and the help command.

You have three different modes available:

  • GLOBAL

  • FIRST

  • SUBSHELL

You can define your default completion mode using the completionMode property in etc/org.apache.karaf.shell.cfg file. By default, you have:

completionMode = GLOBAL

You can also change the completion mode “on the fly” (while using the Karaf shell console) using the shell:completion command:

karaf@root()> shell:completion
GLOBAL
karaf@root()> shell:completion FIRST
karaf@root()> shell:completion
FIRST

shell:completion can inform you about the current completion mode used. You can also provide the new completion mode that you want.

GLOBAL completion mode is the default one in Karaf 3.0.0 (mostly for transition purpose).

GLOBAL mode doesn’t really use subshell: it’s the same behavior as in previous Karaf versions.

When you type the tab key, whatever in which subshell you are, the completion will display all commands and all aliases:

karaf@root()> <TAB>
karaf@root()> Display all 273 possibilities? (y or n)
...
karaf@root()> feature
karaf@root(feature)> <TAB>
karaf@root(feature)> Display all 273 possibilities? (y or n)

FIRST completion mode is an alternative to the GLOBAL completion mode.

If you type the tab key on the root level subshell, the completion will display the commands and the aliases from all subshells (as in GLOBAL mode). However, if you type the tab key when you are in a subshell, the completion will display only the commands of the current subshell:

karaf@root()> shell:completion FIRST
karaf@root()> <TAB>
karaf@root()> Display all 273 possibilities? (y or n)
...
karaf@root()> feature
karaf@root(feature)> <TAB>
karaf@root(feature)>
info install list repo-add repo-list repo-remove uninstall version-list
karaf@root(feature)> exit
karaf@root()> log
karaf@root(log)> <TAB>
karaf@root(log)>
clear display exception-display get log set tail

SUBSHELL completion mode is the real subshell mode.

If you type the tab key on the root level, the completion displays the subshell commands (to go into a subshell), and the global aliases. Once you are in a subshell, if you type the TAB key, the completion displays the commands of the current subshell:

karaf@root()> shell:completion SUBSHELL
karaf@root()> <TAB>
karaf@root()>
* bundle cl config dev feature help instance jaas kar la ld lde log log:list man package region service shell ssh system
karaf@root()> bundle
karaf@root(bundle)> <TAB>
karaf@root(bundle)>
capabilities classes diag dynamic-import find-class headers info install list refresh requirements resolve restart services start start-level stop
uninstall update watch
karaf@root(bundle)> exit
karaf@root()> camel
karaf@root(camel)> <TAB>
karaf@root(camel)>
backlog-tracer-dump backlog-tracer-info backlog-tracer-start backlog-tracer-stop context-info context-list context-start context-stop endpoint-list route-info route-list route-profile route-reset-stats
route-resume route-show route-start route-stop route-suspend

Unix like environment

Karaf console provides a full Unix like environment.

Help or man

We already saw the usage of the help command to display all commands available.

But you can also use the help command to get details about a command or the man command which is an alias to the help command. You can also use another form to get the command help, by using the --help option to the command.

So these commands

karaf@root()> help feature:list
karaf@root()> man feature:list
karaf@root()> feature:list --help

All produce the same help output:

DESCRIPTION
        feature:list

        Lists all existing features available from the defined repositories.

SYNTAX
        feature:list [options]

OPTIONS
        --help
                Display this help message
        -o, --ordered
                Display a list using alphabetical order
        -i, --installed
                Display a list of all installed features only
        --no-format
                Disable table rendered output
Completion

When you type the tab key, Karaf tries to complete:

  • subshell

  • commands

  • aliases

  • command arguments

  • command options

Alias

An alias is another name associated to a given command.

The shell:alias command creates a new alias. For instance, to create the list-installed-features alias to the actual feature:list -i command, you can do:

karaf@root()> alias "list-features-installed = { feature:list -i }"
karaf@root()> list-features-installed
Name       | Version  | Installed | Repository     | Description
---------------------------------------------------------------------------------------------------------
standard   | 3.0.0    | x         | standard-3.0.0 | Karaf standard feature
config     | 3.0.0    | x         | standard-3.0.0 | Provide OSGi ConfigAdmin support
region     | 3.0.0    | x         | standard-3.0.0 | Provide Region Support
package    | 3.0.0    | x         | standard-3.0.0 | Package commands and mbeans
kar        | 3.0.0    | x         | standard-3.0.0 | Provide KAR (KARaf archive) support
ssh        | 3.0.0    | x         | standard-3.0.0 | Provide a SSHd server on Karaf
management | 3.0.0    | x         | standard-3.0.0 | Provide a JMX MBeanServer and a set of MBeans in K

At login, the Apache Karaf console reads the etc/shell.init.script file where you can create your aliases. It’s similar to a bashrc or profile file on Unix.

ld = { log:display $args } ;
lde = { log:exception-display $args } ;
la = { bundle:list -t 0 $args } ;
ls = { service:list $args } ;
cl = { config:list "(service.pid=$args)" } ;
halt = { system:shutdown -h -f $args } ;
help = { *:help $args | more } ;
man = { help $args } ;
log:list = { log:get ALL } ;

You can see here the aliases available by default:

  • ld is a short form to display log (alias to log:display command)

  • lde is a short form to display exceptions (alias to log:exception-display command)

  • la is a short form to list all bundles (alias to bundle:list -t 0 command)

  • ls is a short form to list all services (alias to service:list command)

  • cl is a short form to list all configurations (alias to config:list command)

  • halt is a short form to shutdown Apache Karaf (alias to system:shutdown -h -f command)

  • help is a short form to display help (alias to *:help command)

  • man is the same as help (alias to help command)

  • log:list displays all loggers and level (alias to log:get ALL command)

You can create your own aliases in the etc/shell.init.script file.

Key binding

Like on most Unix environment, Karaf console support some key bindings:

  • the arrows key to navigate in the commands history

  • CTRL-D to logout/shutdown Karaf

  • CTRL-R to search previously executed command

  • CTRL-U to remove the current line

Pipe

You can pipe the output of one command as input to another one. It’s a pipe, using the | character:

karaf@root()> feature:list | grep -i war
war                           | 3.0.0  |           | standard-3.0.0          | Turn Karaf as a full WebContainer
Grep, more, find, …​

Karaf console provides some core commands similar to Unix environment:

  • shell:head displays the first line of the input

  • shell:source executes commands contained in a script

  • shell:alias creates an alias to an existing command

  • shell:history prints the commands history

  • shell:cat displays the content of a file or URL

  • shell:if allows you to use conditions (if, then, else blocks) in script

  • shell:tac captures stdin and returns it as a string

  • shell:clear clears the current console display

  • shell:info prints various information about the current Karaf instance

  • shell:tail displays the last lines of the input

  • shell:completion displays or change the current completion mode

  • shell:java executes a Java application

  • shell:threads prints the current thread

  • shell:date displays the current date (optionally using a format)

  • shell:watch periodically executes a command and refresh the output

  • shell:each executes a closure on a list of arguments

  • shell:more is a file pager

  • shell:wc prints newline, words, and byte counts for each file

  • shell:env gets/sets the value of a shell session variable

  • shell:echo echoes and prints arguments to stdout

  • shell:new creates a new Java object

  • shell:edit calls a text editor on the current file or URL

  • shell:printf formats and prints arguments

  • shell:exec executes a system command

  • shell:sleep sleeps for a bit then wakes up

  • shell:grep prints lines matching the given pattern

  • shell:sort writes sorted concatenation of all files to stdout

You don’t have to use the fully qualified name of the command, you can directly use the command name as long as it is unique. So you can use 'head' instead of 'shell:head'

Again, you can find details and all options of these commands using help command or --help option.

Scripting

The Apache Karaf Console supports a complete scripting language, similar to bash or csh on Unix.

The each (shell:each) command can iterate in a list:

karaf@root()> list = [1 2 3]; each ($list) { echo $it }
1
2
3

You can create the list yourself (as in the previous example), or some commands can return a list too.

We can note that the console created a "session" variable with the name list that you can access with $list.

The $it variable is an implicit one corresponding to the current object (here the current iterated value from the list).

When you create a list with [], Apache Karaf console creates a Java ArrayList. It means that you can use methods available in the ArrayList objects (like get or size for instance):

karaf@root()> list = ["Hello" world]; echo ($list get 0) ($list get 1)
Hello world

We can note here that calling a method on an object is directly using (object method argument). Here ($list get 0) means $list.get(0) where $list is the ArrayList.

The class notation will display details about the object:

karaf@root()> $list class
...
ProtectionDomain     ProtectionDomain  null
 null
 <no principals>
 java.security.Permissions@6521c24e (
 ("java.security.AllPermission" "<all permissions>" "<all actions>")
)


Signers              null
SimpleName           ArrayList
TypeParameters       [E]

You can "cast" a variable to a given type.

karaf@root()> ("hello world" toCharArray)
[h, e, l, l, o,  , w, o, r, l, d]

If it fails, you will see the casting exception:

karaf@root()> ("hello world" toCharArray)[0]
Error executing command: [C cannot be cast to [Ljava.lang.Object;

You can "call" a script using the shell:source command:

karaf@root> shell:source script.txt
True!

where script.txt contains:

foo = "foo"
if { $foo equals "foo" } {
  echo "True!"
}

{warning} The spaces are important when writing script. For instance, the following script is not correct:

if{ $foo equals "foo" } ...

and will fail with:

karaf@root> shell:source script.txt
Error executing command: Cannot coerce echo "true!"() to any of []

because a space is missing after the if statement. {warning}

As for the aliases, you can create init scripts in the etc/shell.init.script file. You can also named you script with an alias. Actually, the aliases are just scripts.

See the Scripting section of the developers guide for details.

Security

The Apache Karaf console supports a Role Based Access Control (RBAC) security mechanism. It means that depending of the user connected to the console, you can define, depending of the user’s groups and roles, the permission to execute some commands, or limit the values allowed for the arguments.

Console security is detailed in the Security section of this guide.