• the special value {@link #PIPE Redirect.PIPE}
• the special value {@link #INHERIT Redirect.INHERIT}
• a redirection to read from a file, created by an invocation of {@link Redirect#from Redirect.from(File)}
• a redirection to write to a file, created by an invocation of {@link Redirect#to Redirect.to(File)}
• a redirection to append to a file, created by an invocation of {@link Redirect#appendTo Redirect.appendTo(File)}

Each of the above categories has an associated unique {@link Type Type}. 

 public ProcessBuilder(List command) 
{
        if (command == null)
            throw new NullPointerException();
        this.command = command;
}

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

Parameters:

command - the list containing the program and its arguments

Throws:

NullPointerException - if the argument is null

 public ProcessBuilder(String command) 
{
        this.command = new ArrayList< String >(command.length);
        for (String arg : command)
            this.command.add(arg);
}

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 {@code command} array, in the same order. It is not checked whether {@code command} corresponds to a valid operating system command.

Parameters:

command - a string array containing the program and its arguments

 public List command() 
{
        return 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.

 public ProcessBuilder command(List command) 
{
        if (command == null)
            throw new NullPointerException();
        this.command = command;
        return this;
}

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

 public ProcessBuilder command(String command) 
{
        this.command = new ArrayList< String >(command.length);
        for (String arg : command)
            this.command.add(arg);
        return this;
}

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 {@code command} array, in the same order. It is not checked whether {@code command} corresponds to a valid operating system command.

 public File directory() 
{
        return directory;
}

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

 public ProcessBuilder directory(File directory) 
{
        this.directory = directory;
        return this;
}

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

 public Map environment() 
{
        SecurityManager security = System.getSecurityManager();
        if (security != null)
            security.checkPermission(new RuntimePermission("getenv.*"));
        if (environment == null)
            environment = ProcessEnvironment.environment();
        assert environment != null;
        return 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 System#getenv() ). Subprocesses subsequently started by this object's #start() method will use this map as their environment.

The returned object may be modified using ordinary Map operations. These modifications will be visible to subprocesses started via the #start() method. Two {@code ProcessBuilder} instances always contain independent process environments, so changes to the returned map will never be reflected in any other {@code ProcessBuilder} instance or the values returned by 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 NullPointerException . Attempting to query the presence of a key or value which is not of type String will throw a 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 UnsupportedOperationException or 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 Object#equals and Object#hashCode methods.

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

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

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

 ProcessBuilder environment(String[] envp) 
{
        assert environment == null;
        if (envp != null) {
            environment = ProcessEnvironment.emptyEnvironment(envp.length);
            assert environment != null;
            for (String envstring : envp) {
                // Before 1.5, we blindly passed invalid envstrings
                // to the child process.
                // We would like to throw an exception, but do not,
                // for compatibility with old broken code.
                // Silently discard any trailing junk.
                if (envstring.indexOf((int) '\u0000") != -1)
                    envstring = envstring.replaceFirst("\u0000.*", "");
                int eqlsign =
                    envstring.indexOf('=", ProcessEnvironment.MIN_NAME_LENGTH);
                // Silently ignore envstrings lacking the required `='.
                if (eqlsign != -1)
                    environment.put(envstring.substring(0,eqlsign),
                                    envstring.substring(eqlsign+1));
            }
        }
        return this;
}

 public ProcessBuilder inheritIO() 
{
        Arrays.fill(redirects(), Redirect.INHERIT);
        return this;
}

Sets the source and destination for subprocess standard I/O to be the same as those of the current Java process.

This is a convenience method. An invocation of the form

 {@code
pb.inheritIO()
}

behaves in exactly the same way as the invocation

 {@code
pb.redirectInput(Redirect.INHERIT)
.redirectOutput(Redirect.INHERIT)
.redirectError(Redirect.INHERIT)
}

This gives behavior equivalent to most operating system command interpreters, or the standard C library function {@code system()}.

 public ProcessBuilder.Redirect redirectError() 
{
        return (redirects == null) ? Redirect.PIPE : redirects[2];
}

Returns this process builder's standard error destination. Subprocesses subsequently started by this object's #start() method redirect their standard error to this destination. The initial value is Redirect.PIPE .

 public ProcessBuilder redirectError(ProcessBuilder.Redirect destination) 
{
        if (destination.type() == Redirect.Type.READ)
            throw new IllegalArgumentException(
                "Redirect invalid for writing: " + destination);
        redirects()[2] = destination;
        return this;
}

Sets this process builder's standard error destination. Subprocesses subsequently started by this object's #start() method send their standard error to this destination.

If the destination is Redirect.PIPE (the initial value), then the error output of a subprocess can be read using the input stream returned by Process#getErrorStream() . If the destination is set to any other value, then Process#getErrorStream() will return a null input stream.

If the redirectErrorStream attribute has been set {@code true}, then the redirection set by this method has no effect.

 public ProcessBuilder redirectError(File file) 
{
        return redirectError(Redirect.to(file));
}

Sets this process builder's standard error destination to a file.

This is a convenience method. An invocation of the form {@code redirectError(file)} behaves in exactly the same way as the invocation redirectError {@code (Redirect.to(file))}.

 public boolean redirectErrorStream() 
{
        return redirectErrorStream;
}

Tells whether this process builder merges standard error and standard output.

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

 public ProcessBuilder redirectErrorStream(boolean redirectErrorStream) 
{
        this.redirectErrorStream = redirectErrorStream;
        return this;
}

Sets this process builder's {@code redirectErrorStream} property.

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

 public ProcessBuilder.Redirect redirectInput() 
{
        return (redirects == null) ? Redirect.PIPE : redirects[0];
}

Returns this process builder's standard input source. Subprocesses subsequently started by this object's #start() method obtain their standard input from this source. The initial value is Redirect.PIPE .

 public ProcessBuilder redirectInput(ProcessBuilder.Redirect source) 
{
        if (source.type() == Redirect.Type.WRITE ||
            source.type() == Redirect.Type.APPEND)
            throw new IllegalArgumentException(
                "Redirect invalid for reading: " + source);
        redirects()[0] = source;
        return this;
}

Sets this process builder's standard input source. Subprocesses subsequently started by this object's #start() method obtain their standard input from this source.

If the source is Redirect.PIPE (the initial value), then the standard input of a subprocess can be written to using the output stream returned by Process#getOutputStream() . If the source is set to any other value, then Process#getOutputStream() will return a null output stream.

 public ProcessBuilder redirectInput(File file) 
{
        return redirectInput(Redirect.from(file));
}

Sets this process builder's standard input source to a file.

This is a convenience method. An invocation of the form {@code redirectInput(file)} behaves in exactly the same way as the invocation redirectInput {@code (Redirect.from(file))}.

 public ProcessBuilder.Redirect redirectOutput() 
{
        return (redirects == null) ? Redirect.PIPE : redirects[1];
}

Returns this process builder's standard output destination. Subprocesses subsequently started by this object's #start() method redirect their standard output to this destination. The initial value is Redirect.PIPE .

 public ProcessBuilder redirectOutput(ProcessBuilder.Redirect destination) 
{
        if (destination.type() == Redirect.Type.READ)
            throw new IllegalArgumentException(
                "Redirect invalid for writing: " + destination);
        redirects()[1] = destination;
        return this;
}

Sets this process builder's standard output destination. Subprocesses subsequently started by this object's #start() method send their standard output to this destination.

If the destination is Redirect.PIPE (the initial value), then the standard output of a subprocess can be read using the input stream returned by Process#getInputStream() . If the destination is set to any other value, then Process#getInputStream() will return a null input stream.

 public ProcessBuilder redirectOutput(File file) 
{
        return redirectOutput(Redirect.to(file));
}

Sets this process builder's standard output destination to a file.

This is a convenience method. An invocation of the form {@code redirectOutput(file)} behaves in exactly the same way as the invocation redirectOutput {@code (Redirect.to(file))}.

 public Process start() throws IOException 
{
        // Must convert to array first -- a malicious user-supplied
        // list might try to circumvent the security check.
        String[] cmdarray = command.toArray(new String[command.size()]);
        for (String arg : cmdarray)
            if (arg == null)
                throw new NullPointerException();
        // Throws IndexOutOfBoundsException if command is empty
        String prog = cmdarray[0];
        SecurityManager security = System.getSecurityManager();
        if (security != null)
            security.checkExec(prog);
        String dir = directory == null ? null : directory.toString();
        try {
            return ProcessImpl.start(cmdarray,
                                     environment,
                                     dir,
                                     redirects,
                                     redirectErrorStream);
        } catch (IOException e) {
            // It's much easier for us to create a high-quality error
            // message than the low-level C code which found the problem.
            throw new IOException(
                "Cannot run program \"" + prog + "\""
                + (dir == null ? "" : " (in directory \"" + dir + "\")")
                + ": " + e.getMessage(),
                e);
        }
}

Starts a new process using the attributes of this process builder.

The new process will invoke the command and arguments given by #command() , in a working directory as given by #directory() , with a process environment as given by #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 checkExec method is called with the first component of this object's {@code command} array as its argument. This may result in a SecurityException being thrown.

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

• The operating system program file was not found.
• Access to the program file was denied.
• The working directory does not exist.

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 IOException .

Subsequent modifications to this process builder will not affect the returned Process .