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The Groovy Shell, aka. groovysh is a command-line application which allows easy access to evaluate Groovy expressions, define classes and run simple experiments.
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Features
- No need for
gocommand to execute buffer. - Rich cross-platform edit-line editing, history and completion thanks to JLine.
- ANSI colors (prompt, exception traces, etc).
- Simple, yet robust, command system with online help, user alias support and more.
- User profile support
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The shell supports several options to control verbosity, ANSI coloring and other features.
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./bin/groovysh --help
usage: groovysh [options] [...]
-C, --color[=FLAG] Enable or disable use of ANSI colors
-D, --define=NAME=VALUE Define a system property
-T, --terminal=TYPE Specify the terminal TYPE to use
-V, --version Display the version
-d, --debug Enable debug output
-h, --help Display this help message
-q, --quiet Suppress superfluous output
-v, --verbose Enable verbose output
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Execute a Command
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./bin/groovysh 'show preferences'
No preferences are set
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Evaluate an Expression
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./bin/groovysh 'System.properties.each { k, v -> println("$k = $v") }'
java.runtime.name = Java(TM) 2 Runtime Environment, Standard Edition
sun.boot.library.path = /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Libraries
java.vm.version = 1.5.0_07-87
awt.nativeDoubleBuffering = true
gopherProxySet = false
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Simple Expressions
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println "Hello"
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Evaluation Result
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Multi-line/complex expressions (like closure or class definitions) may be defined over several lines. When the shell detects that it has a complete expression it will compile and evaluate it.
Define a Class
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class Foo {
def bar() {
println "baz"
}
}
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Use the Class
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foo = new Foo()
foo.bar()
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This will set a shell variable:
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foo = "bar"
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But, this will evaluate a local variable and will not be saved to the shell's environment:
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def foo = "bar"
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Functions
Functions can be defined in the shell, and will be saved for later use.
Defining a function is easy:
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groovy:000> def hello(name) {
groovy:001> println("Hello $name")
groovy:002> }
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And then using it is as one might expect:
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hello("Jason")
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Internally the shell creates a closure to encapsulate the function and then binds the closure to a variable. So variables and functions share the same namespace. |
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The Command List
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groovy:000> help
For information about Groovy, visit:
http://groovy.codehaus.org
Available commands:
help (\h ) Display this help message
? (\? ) Alias to: help
exit (\x ) Exit the shell
quit (\q ) Alias to: exit
import (\i ) Import a class into the namespace
display (\d ) Display the current buffer
clear (\c ) Clear the buffer
show (\S ) Show variables, classes or imports
inspect (\n ) Inspect a variable or the last result with the GUI object browser
purge (\p ) Purge variables, classes, imports or buffers
edit (\e ) Edit the current buffer
load (\l ) Load a file or URL into the buffer
. (\. ) Alias to: load
save (\s ) Save the current buffer to a file
record (\r ) Record the current session to a file
history (\H ) Display, manage and recall edit-line history
alias (\a ) Create an alias
set (\= ) Set (or list) preferences
For help on a specific command type:
help <command>
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While in the interactive shell, you can ask for help for any command to get more details about its syntax or function. Here is an example of what happens when you ask for help for the help command:
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groovy:000> help help
usage: help [<command>]
Display the list of commands or the help text for <command>.
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This only displays the buffer of an incomplete expression. Once the expression is complete, the buffer is rest. The prompt will update to show the size of the current buffer as well.
Example
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groovy:000> class Foo {
groovy:001> def bar
groovy:002> def baz() {
groovy:003> display
001> class Foo {
002> def bar
003> def baz() {
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clear
Clear the current buffer.s the current buffer, resetting the prompt counter to 000. Can be used to recover from compilation errors.
show
Show variables, classes or preferences or imports.
show variables
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groovy:000> show variables
Variables:
_ = true
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| Tip | ||
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To use
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Setting a Preference
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set verbosity DEBUG
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Listing Preferences
To list the current set preferences (and their values):
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show preferences
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At the moment, there is no way to list all of the known/available preferences to be set. |
Clearing Preferences (ie. Resetting to Defaults)
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purge preferences
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User Profile Scripts and State
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These shots have been taken over the development of the new shell, so some of the content might look slightly different. Also, note the yellow colors here are the shell's bold color, so the colors might look different depending on how the enclosing shell has its colors setup.
Troubleshooting
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nonefalseoffjline.UnsupportedTerminal
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groovysh --terminal=none
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Problems with Cygwin on Windows
Some people have issues when running groovysh with cygwin. If you have troubles, the following may help:
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stty -icanon min 1 -echo
groovysh --terminal=unix
stty icanon echo
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