This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


java.lang
class ProcessBuilder

java.lang.Object extended by java.lang.ProcessBuilder

public final class ProcessBuilder
extends Object

This class is used to create operating system processes.

Each ProcessBuilder instance manages a collection of process attributes. The {@link #start()} method creates a new {@link Process} instance with those attributes. The {@link #start()} method can be invoked repeatedly from the same instance to create new subprocesses with identical or related attributes.

Each process builder manages these process attributes:

Modifying a process builder's attributes will affect processes subsequently started by that object's {@link #start()} method, but will never affect previously started processes or the Java process itself.

Most error checking is performed by the {@link #start()} method. It is possible to modify the state of an object so that {@link #start()} will fail. For example, setting the command attribute to an empty list will not throw an exception unless {@link #start()} is invoked.

Note that this class is not synchronized. If multiple threads access a ProcessBuilder instance concurrently, and at least one of the threads modifies one of the attributes structurally, it must be synchronized externally.

Starting a new process which uses the default working directory and environment is easy:

 Process p = new ProcessBuilder("myCommand", "myArg").start();
 

Here is an example that starts a process with a modified working directory and environment:

 ProcessBuilder pb = new ProcessBuilder("myCommand", "myArg1", "myArg2");
 Map<String, String> env = pb.environment();
 env.put("VAR1", "myValue");
 env.remove("OTHERVAR");
 env.put("VAR2", env.get("VAR1") + "suffix");
 pb.directory(new File("myDir"));
 Process p = pb.start();
 

To start a process with an explicit set of environment variables, first call {@link java.util.Map#clear() Map.clear()} before adding environment variables.


Constructor Summary

          Constructs a process builder with the specified operating system program and arguments.

          Constructs a process builder with the specified operating system program and arguments.
 
Method Summary
 List

          Returns this process builder's operating system program and arguments.
 ProcessBuilder
command(List command)

          Sets this process builder's operating system program and arguments.
 ProcessBuilder
command(String[] command)

          Sets this process builder's operating system program and arguments.
 File

          Returns this process builder's working directory.
 ProcessBuilder
directory(File directory)

          Sets this process builder's working directory.
 Map

          Returns a string map view of this process builder's environment.
 boolean

          Tells whether this process builder merges standard error and standard output.
 ProcessBuilder
redirectErrorStream(boolean redirectErrorStream)

          Sets this process builder's redirectErrorStream property.
 Process

          Starts a new process using the attributes of this process builder.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ProcessBuilder

public ProcessBuilder(List command)
Constructs a process builder with the specified operating system program and arguments. This constructor does not make a copy of the command list. Subsequent updates to the list will be reflected in the state of the process builder. It is not checked whether command corresponds to a valid operating system command.

Parameters:
command - The list containing the program and its arguments

ProcessBuilder

public ProcessBuilder(String[] command)
Constructs a process builder with the specified operating system program and arguments. This is a convenience constructor that sets the process builder's command to a string list containing the same strings as the command array, in the same order. It is not checked whether command corresponds to a valid operating system command.

Parameters:
command - A string array containing the program and its arguments
Method Detail

command

public List command()
Returns this process builder's operating system program and arguments. The returned list is not a copy. Subsequent updates to the list will be reflected in the state of this process builder.

Returns:
This process builder's program and its arguments

command

public ProcessBuilder command(List command)
Sets this process builder's operating system program and arguments. This method does not make a copy of the command list. Subsequent updates to the list will be reflected in the state of the process builder. It is not checked whether command corresponds to a valid operating system command.

Parameters:
command - The list containing the program and its arguments
Returns:
This process builder

command

public ProcessBuilder command(String[] command)
Sets this process builder's operating system program and arguments. This is a convenience method that sets the command to a string list containing the same strings as the command array, in the same order. It is not checked whether command corresponds to a valid operating system command.

Parameters:
command - A string array containing the program and its arguments
Returns:
This process builder

directory

public File directory()
Returns this process builder's working directory. Subprocesses subsequently started by this object's {@link #start()} method will use this as their working directory. The returned value may be null -- this means to use the working directory of the current Java process, usually the directory named by the system property user.dir, as the working directory of the child process.

Returns:
This process builder's working directory

directory

public ProcessBuilder directory(File directory)
Sets this process builder's working directory. Subprocesses subsequently started by this object's {@link #start()} method will use this as their working directory. The argument may be null -- this means to use the working directory of the current Java process, usually the directory named by the system property user.dir, as the working directory of the child process.

Parameters:
directory - The new working directory
Returns:
This process builder

environment

public Map environment()
Returns a string map view of this process builder's environment. Whenever a process builder is created, the environment is initialized to a copy of the current process environment (see {@link System#getenv()}). Subprocesses subsequently started by this object's {@link #start()} method will use this map as their environment.

The returned object may be modified using ordinary {@link java.util.Map Map} operations. These modifications will be visible to subprocesses started via the {@link #start()} method. Two ProcessBuilder instances always contain independent process environments, so changes to the returned map will never be reflected in any other ProcessBuilder instance or the values returned by {@link System#getenv System.getenv}.

If the system does not support environment variables, an empty map is returned.

The returned map does not permit null keys or values. Attempting to insert or query the presence of a null key or value will throw a {@link NullPointerException}. Attempting to query the presence of a key or value which is not of type {@link String} will throw a {@link ClassCastException}.

The behavior of the returned map is system-dependent. A system may not allow modifications to environment variables or may forbid certain variable names or values. For this reason, attempts to modify the map may fail with {@link UnsupportedOperationException} or {@link IllegalArgumentException} if the modification is not permitted by the operating system.

Since the external format of environment variable names and values is system-dependent, there may not be a one-to-one mapping between them and Java's Unicode strings. Nevertheless, the map is implemented in such a way that environment variables which are not modified by Java code will have an unmodified native representation in the subprocess.

The returned map and its collection views may not obey the general contract of the {@link Object#equals} and {@link Object#hashCode} methods.

The returned map is typically case-sensitive on all platforms.

If a security manager exists, its {@link SecurityManager#checkPermission checkPermission} method is called with a {@link RuntimePermission}("getenv.*") permission. This may result in a {@link SecurityException} being thrown.

When passing information to a Java subprocess, system properties are generally preferred over environment variables.

Returns:
This process builder's environment

redirectErrorStream

public boolean redirectErrorStream()
Tells whether this process builder merges standard error and standard output.

If this property is true, then any error output generated by subprocesses subsequently started by this object's {@link #start()} method will be merged with the standard output, so that both can be read using the {@link Process#getInputStream()} method. This makes it easier to correlate error messages with the corresponding output. The initial value is false.

Returns:
This process builder's redirectErrorStream property

redirectErrorStream

public ProcessBuilder redirectErrorStream(boolean redirectErrorStream)
Sets this process builder's redirectErrorStream property.

If this property is true, then any error output generated by subprocesses subsequently started by this object's {@link #start()} method will be merged with the standard output, so that both can be read using the {@link Process#getInputStream()} method. This makes it easier to correlate error messages with the corresponding output. The initial value is false.

Parameters:
redirectErrorStream - The new property value
Returns:
This process builder

start

public Process start()
              throws IOException
Starts a new process using the attributes of this process builder.

The new process will invoke the command and arguments given by {@link #command()}, in a working directory as given by {@link #directory()}, with a process environment as given by {@link #environment()}.

This method checks that the command is a valid operating system command. Which commands are valid is system-dependent, but at the very least the command must be a non-empty list of non-null strings.

If there is a security manager, its {@link SecurityManager#checkExec checkExec} method is called with the first component of this object's command array as its argument. This may result in a {@link SecurityException} being thrown.

Starting an operating system process is highly system-dependent. Among the many things that can go wrong are:

In such cases an exception will be thrown. The exact nature of the exception is system-dependent, but it will always be a subclass of {@link IOException}.

Subsequent modifications to this process builder will not affect the returned {@link Process}.

Returns:
A new {@link Process} object for managing the subprocess
Throws:
IOException - If an I/O error occurs


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.