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JavaScript Shell
The JavaScript shell provides a simple way to run scripts in batch mode or an interactive environment for exploratory programming.
Invoking the Shell
java org.mozilla.javascript.tools.shell.Main [options] script-filename-or-url [script-arguments]
where options are:
-e script-source- Executes script-source as a JavaScript script.
-f script-filename-or-url- Reads script-filename-or-url content and execute it as a JavaScript script.
-opt optLevel-O optLevel- Optimizes at level optLevel, which must be an integer between 0 and 9. See Optimization for more details.
-version versionNumber- Specifies the language version to compile with. The string versionNumber must be one of 100, 110, 120, 130, or 140. See JavaScript Language Versions for more information on language versions.
-strict- Enable strict mode.
-continuations- Enable experiments support for continuations and set the optimization level to -1 to force interpretation mode.
If the shell is invoked with the system property rhino.use_java_policy_security set to true and with a security manager installed, the shell restricts scripts permissions based on their URLs according to Java policy settings. This is available only if JVM implements Java2 security model.
Predefined Properties
Scripts executing in the shell have access to some additional properties of the top-level object.
- arguments
- The
argumentsobject is an array containing the strings of all the arguments given at the command line when the shell was invoked. - help()
- Executing the help function will print usage and help messages.
- defineClass(className)
- Define an extension using the Java class named with the string argument className. Uses ScriptableObject.defineClass() to define the extension.
- deserialize(filename)
- Restore from the specified file an object previously written
by a call to
serialize. - load([filename, ...])
- Load JavaScript source files named by string arguments. If multiple arguments are given, each file is read in and executed in turn.
- loadClass(className)
- Load and execute the class named by the string argument className. The class must be a class that implements the Script interface, as will any script compiled by jsc.
- print([expr ...])
- Evaluate and print expressions. Evaluates each expression, converts the result to a string, and prints it.
- readFile(path [, characterCoding)
- Read given file and convert its bytes to a string using the specified character coding or default character coding if explicit coding argument is not given.
- readUrl(url [, characterCoding)
- Open an input connection to the given string url, read all its bytes and convert them to a string using the specified character coding or default character coding if explicit coding argument is not given.
- runCommand(commandName, [arg, ...] [options])
- Execute the specified command with the given argument and options as a separate process and return the exit status of the process. For details, see JavaDoc for org.mozilla.javascript.tools.shell.Global#runCommand.
- seal(object)
- Seal the specified object so any attempt to add, delete or modify its properties would throw an exception.
- serialize(object, filename)
- Serialize the given object to the specified file.
- spawn(functionOrScript)
- Run the given function or script in a different thread.
- sync(function)
- creates a synchronized function (in the sense of a Java
synchronized method) from an existing function. The new function
synchronizes on the
thisobject of its invocation. - quit()
- Quit shell. The shell will also quit in interactive mode if an end-of-file character is typed at the prompt.
- version([number])
- Get or set JavaScript version number. If no argument is supplied, the current version number is returned. If an argument is supplied, it is expected to be one of 100, 110, 120, 130, or 140 to indicate JavaScript version 1.0, 1.1, 1.2, 1.3, or 1.4 respectively.
Example
Invocation
Here the shell is invoked three times from the command line. (The system
command prompt is shown as $.) The first invocation executes a
script specified on the command line itself. The next invocation has no
arguments, so the shell goes into interactive mode, reading and evaluating
each line as it is typed in. Finally, the last invocation executes a script
from a file and accesses arguments to the script itself.
$ java org.mozilla.javascript.tools.shell.Main -e print('hi')
hi
$ java org.mozilla.javascript.tools.shell.Main
js> print('hi')
hi
js> 6*7
42
js> function f() {
return a;
}
js> var a = 34;
js> f()
34
js> quit()
$ cat echo.js
for (i in arguments) {
print(arguments[i])
}
$ java org.mozilla.javascript.tools.shell.Main echo.js foo bar
foo
bar
$
spawn and sync
The following example creates 2 threads via
spawn and uses sync
to create a synchronized version of the function
test.
js> function test(x) {
print("entry");
java.lang.Thread.sleep(x*1000);
print("exit");
}
js> var o = { f : sync(test) };
js> spawn(function() {o.f(5);});
Thread[Thread-0,5,main]
entry
js> spawn(function() {o.f(5);});
Thread[Thread-1,5,main]
js>
exit
entry
exit
runCommand
Here is few examples of invoking runCommand
under Linux.
js> runCommand('date')
Thu Jan 23 16:49:36 CET 2003
0
// Using input option to provide process input
js> runCommand("sort", {input: "c\na\nb"})
a
b
c
0
js> // Demo of output and err options
js> var opt={input: "c\na\nb", output: 'Sort Output:\n'}
js> runCommand("sort", opt)
0
js> print(opt.output)
Sort Output:
a
b
c
js> var opt={input: "c\na\nb", output: 'Sort Output:\n', err: ''}
js> runCommand("sort", "--bad-arg", opt)
2
js> print(opt.err)
/bin/sort: unrecognized option `--bad-arg'
Try '/bin/sort --help' for more information.
js> runCommand("bad_command", "--bad-arg", opt)
js: "<stdin>", line 18: uncaught JavaScript exception: java.io.IOException:
bad_command: not found
js> // Passing explicit environment to the system shell
js> runCommand("sh", "-c", "echo $env1 $env2", { env: {env1: 100, env2: 200}})
100 200
0
js> // Use args option to provide additional command arguments
js> var arg_array = [1, 2, 3, 4];
js> runCommand("echo", { args: arg_array})
1 2 3 4
0
Examples for Windows are similar:
js> // Invoke shell command
js> runCommand("cmd", "/C", "date /T")
27.08.2005
0
js> // Run sort collectiong the output
js> var opt={input: "c\na\nb", output: 'Sort Output:\n'}
js> runCommand("sort", opt)
0
js> print(opt.output)
Sort Output:
a
b
c
js> // Invoke notepad and wait until it exits
js> runCommand("notepad")
0