util
Class Shell

java.lang.Object
  util.Shell

public class Shell
extends Object

Utility class which acts like a system shell manipulable from Java code.

Field Summary

protected File	cwd The current working directory.
protected int	lastExitValue The exit value of the last command executed.
protected PrintStream	stderr The stream to use for standard error.
protected InputStream	stdin The stream to use for standard input.
protected PrintStream	stdout The stream to use for standard output.

Constructor Summary

Shell()

Method Summary

Shell	chdir(File dir) Change directory.
Process	fork(String... cmdLine) Run a process within this shell, in the background.
File	getCwd() Get the current directory.
int	getLastExitValue()
PrintStream	getStdErr()
InputStream	getStdIn()
PrintStream	getStdOut()
int	run(String... cmdLine) Run a process within this shell.
int	runClass(Class<?> cls, String... args) Run a Java class as a process within this shell.
Shell	setStdErr(PrintStream stderr)
Shell	setStdIn(InputStream stdin)
Shell	setStdOut(PrintStream stdout)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cwd

protected File cwd

The current working directory.

stdout

protected PrintStream stdout

The stream to use for standard output.

stderr

protected PrintStream stderr

The stream to use for standard error.

stdin

protected InputStream stdin

The stream to use for standard input.

lastExitValue

protected int lastExitValue

The exit value of the last command executed.

Constructor Detail

Shell

public Shell()

Method Detail

getCwd

public File getCwd()

Get the current directory. Analogous to pwd.

Returns:

The current working directory.

chdir

public Shell chdir(File dir)
            throws IOException

Change directory. Analogous to cd.

Parameters:

dir - The directory to change to.

Returns:

this, for chaining.

Throws:

IOException - If cwd is not a directory or does not exist.

getStdErr

public PrintStream getStdErr()

Returns:

The stream to be used as standard error by processes spawned by this shell.

setStdErr

public Shell setStdErr(PrintStream stderr)

Parameters:

stderr - A stream which will receive anything a child process sends to its standard error stream. By default this will be System.err, that is, the system-wide standard error stream.

Returns:

this, for chaining.

getStdIn

public InputStream getStdIn()

Returns:

The stream to be used as standard input by processes spawned by this shell.

setStdIn

public Shell setStdIn(InputStream stdin)

Parameters:

stdin - A stream to be connected to standard input for child processes. By default this will be System.in, that is, the system-wide standard input stream.

Returns:

this, for chaining.

getStdOut

public PrintStream getStdOut()

Returns:

The stream to be used as standard output by processes spawned by this shell.

setStdOut

public Shell setStdOut(PrintStream stdout)

Parameters:

stdout - A stream which will receive anything a child process sends to its standard output stream. By default this will be System.err, that is, the system-wide standard output stream.

Returns:

this, for chaining.

run

public int run(String... cmdLine)
        throws IOException,
               InterruptedException

Run a process within this shell.

Parameters:

cmdLine - The command line, split into its arguments. No shell-like processing - word splitting, variable substitution, etc. - will be performed.

Returns:

The exit code returned by the program.

Throws:

IOException - If the program cannot be found or run.

InterruptedException - If this thread is interrupted while the program is running.

fork

public Process fork(String... cmdLine)
             throws IOException

Run a process within this shell, in the background.

Parameters:

cmdLine - The command line, split into its arguments. No shell-like processing - word splitting, variable substitution, etc. - will be performed.

Returns:

The process, or null if it could not be started.

Throws:

IOException - If the program cannot be found or run.

runClass

public int runClass(Class<?> cls,
                    String... args)
             throws IOException,
                    InterruptedException

Run a Java class as a process within this shell.

Parameters:

cls - The class to run. Must declare a method with signature public static void main(String[]).

args - Arguments to pass to the class's main method.

Returns:

The exit value returned by the VM.

Throws:

IOException - For any problems relating to I/O (not being able to access the class file, etc.)

InterruptedException - If this thread is interrupted while the class is running.

IllegalArgumentException - If cls does not declare a method with the correct signature.

getLastExitValue

public int getLastExitValue()

Returns:

The exit value of the last process run by this shell.