com.trolltech.qt.core
Class QProcess

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.core.QIODevice
                      extended by com.trolltech.qt.core.QProcess
All Implemented Interfaces:
QtJambiInterface

public class QProcess
extends QIODevice

The QProcess class is used to start external programs and to communicate with them. To start a process, pass the name and command line arguments of the program you want to run as arguments to start(). For example:

        QObject parent = QApplication.instance();
...
        String program = "./path/to/my/favorite/program";

        List<String> arguments = new Vector<String>();
        arguments.add("-style");
        arguments.add("motif");

        QProcess myProcess = new QProcess(parent);
        myProcess.start(program, arguments);
QProcess then enters the Starting state, and when the program has started, QProcess enters the Running state and emits started() .

QProcess allows you to treat a process as a sequential I/O device. You can write to and read from the process just as you would access a network connection using QTcpSocket. You can then write to the process's standard input by calling write(), and read the standard output by calling read(), readLine(), and getChar(). Because it inherits QIODevice, QProcess can also be used as an input source for QXmlReader, or for generating data to be uploaded using QFtp.

Note: On Windows CE, reading and writing to a process is not supported.

When the process exits, QProcess reenters the NotRunning state (the initial state), and emits finished() .

The finished() signal provides the exit code and exit status of the process as arguments, and you can also call exitCode() to obtain the exit code of the last process that finished, and exitStatus() to obtain its exit status. If an error occurs at any point in time, QProcess will emit the error() signal. You can also call error() to find the type of error that occurred last, and state() to find the current process state.

Communicating via Channels

Processes have two predefined output channels: The standard output channel (stdout) supplies regular console output, and the standard error channel (stderr) usually supplies the errors that are printed by the process. These channels represent two separate streams of data. You can toggle between them by calling setReadChannel(). QProcess emits readyRead() when data is available on the current read channel. It also emits readyReadStandardOutput() when new standard output data is available, and when new standard error data is available, readyReadStandardError() is emitted. Instead of calling read(), readLine(), or getChar(), you can explicitly read all data from either of the two channels by calling readAllStandardOutput() or readAllStandardError().

The terminology for the channels can be misleading. Be aware that the process's output channels correspond to QProcess's read channels, whereas the process's input channels correspond to QProcess's write channels. This is because what we read using QProcess is the process's output, and what we write becomes the process's input.

QProcess can merge the two output channels, so that standard output and standard error data from the running process both use the standard output channel. Call setProcessChannelMode() with MergedChannels before starting the process to activative this feature. You also have the option of forwarding the output of the running process to the calling, main process, by passing ForwardedChannels as the argument.

Certain processes need special environment settings in order to operate. You can set environment variables for your process by calling setEnvironment(). To set a working directory, call setWorkingDirectory(). By default, processes are run in the current working directory of the calling process.

Synchronous Process API

QProcess provides a set of functions which allow it to be used without an event loop, by suspending the calling thread until certain signals are emitted: Calling these functions from the main thread (the thread that calls QApplication::exec()) may cause your user interface to freeze.

The following example runs gzip to compress the string "Qt rocks!", without an event loop:

        QProcess gzip = new QProcess();
        List<String> args = new Vector<String>();
        args.add("-c");

        gzip.start("gzip", args);
        if (!gzip.waitForStarted())
            return false;

        gzip.write(new QByteArray("Qt rocks!"));
        gzip.closeWriteChannel();

        if (!gzip.waitForFinished())
            return false;

        QByteArray result = gzip.readAll();
    

Notes for Windows Users

Some Windows commands (for example, dir) are not provided by separate applications, but by the command interpreter itself. If you attempt to use QProcess to execute these commands directly, it won't work. One possible solution is to execute the command interpreter itself (cmd.exe on some Windows systems), and ask the interpreter to execute the desired command.

See also:
QBuffer, QFile, and QTcpSocket.


Nested Class Summary
static class QProcess.DetachedProcessInfo
           
static class QProcess.ExitStatus
          This enum describes the different exit statuses of QProcess.
static class QProcess.ProcessChannel
           
static class QProcess.ProcessChannelMode
          This enum describes the process channel modes of QProcess.
static class QProcess.ProcessError
          This enum describes the different types of errors that are reported by QProcess.
static class QProcess.ProcessState
          This enum describes the different states of QProcess.
 
Nested classes/interfaces inherited from class com.trolltech.qt.core.QIODevice
QIODevice.OpenMode, QIODevice.OpenModeFlag
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 QSignalEmitter.Signal1 error
          This signal takes 1 generic argument(s).
 QSignalEmitter.Signal1 finished
          This signal takes 1 generic argument(s).
 QSignalEmitter.Signal2 finishedWithStatusCode
          This signal takes 2 generic argument(s).
 QSignalEmitter.Signal0 readyReadStandardError
          This signal is emitted when the process has made new data available through its standard error channel (stderr).
 QSignalEmitter.Signal0 readyReadStandardOutput
          This signal is emitted when the process has made new data available through its standard output channel (stdout).
 QSignalEmitter.Signal0 started
          This signal is emitted by QProcess when the process has started, and state() returns Running .
 QSignalEmitter.Signal1 stateChanged
          This signal takes 1 generic argument(s).
 
Fields inherited from class com.trolltech.qt.core.QIODevice
aboutToClose, bytesWritten, readChannelFinished, readyRead
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QProcess()
          Constructs a QProcess object with the given parent.
QProcess(QObject parent)
          Constructs a QProcess object with the given parent.
 
Method Summary
 void closeReadChannel(QProcess.ProcessChannel channel)
          Closes the read channel channel.
 void closeWriteChannel()
          Schedules the write channel of QProcess to be closed.
 java.util.List environment()
          Returns the environment that QProcess will use when starting a process, or an empty QStringList if no environment has been set using setEnvironment().
 QProcess.ProcessError error()
          Returns the type of error that occurred last.
static int execute(java.lang.String program)
          This is an overloaded member function, provided for convenience.
static int execute(java.lang.String program, java.util.List arguments)
          Starts the program program with the arguments arguments in a new process, waits for it to finish, and then returns the exit code of the process.
 int exitCode()
          Returns the exit code of the last process that finished.
 QProcess.ExitStatus exitStatus()
          Returns the exit status of the last process that finished.
 void kill()
          Kills the current process, causing it to exit immediately.
 QProcess.ProcessChannelMode processChannelMode()
          Returns the channel mode of the QProcess standard output and standard error channels.
 QByteArray readAllStandardError()
          Regardless of the current read channel, this function returns all data available from the standard error of the process as a QByteArray.
 QByteArray readAllStandardOutput()
          Regardless of the current read channel, this function returns all data available from the standard output of the process as a QByteArray.
 QProcess.ProcessChannel readChannel()
          Returns the current read channel of the QProcess.
 void setEnvironment(java.util.List environment)
          Sets the environment that QProcess will use when starting a process to the environment specified which consists of a list of key=value pairs.
 void setProcessChannelMode(QProcess.ProcessChannelMode mode)
          Sets the channel mode of the QProcess standard output and standard error channels to the mode specified.
protected  void setProcessState(QProcess.ProcessState state)
          Sets the current state of the QProcess to the state specified.
 void setReadChannel(QProcess.ProcessChannel channel)
          Sets the current read channel of the QProcess to the given channel.
 void setStandardErrorFile(java.lang.String fileName)
          Redirects the process' standard error to the file fileName.
 void setStandardErrorFile(java.lang.String fileName, QIODevice.OpenMode mode)
          Redirects the process' standard error to the file fileName.
 void setStandardErrorFile(java.lang.String fileName, QIODevice.OpenModeFlag[] mode)
          This is an overloaded method provided for convenience.
 void setStandardInputFile(java.lang.String fileName)
          Redirects the process' standard input to the file indicated by fileName.
 void setStandardOutputFile(java.lang.String fileName)
          Redirects the process' standard output to the file fileName.
 void setStandardOutputFile(java.lang.String fileName, QIODevice.OpenMode mode)
          Redirects the process' standard output to the file fileName.
 void setStandardOutputFile(java.lang.String fileName, QIODevice.OpenModeFlag[] mode)
          This is an overloaded method provided for convenience.
 void setStandardOutputProcess(QProcess destination)
          Pipes the standard output stream of this process to the destination process' standard input.
protected  void setupChildProcess()
          This function is called in the child process context just before the program is executed on Unix or Mac OS X (i.
 void setWorkingDirectory(java.lang.String dir)
          Sets the working directory to dir.
 void start(java.lang.String program)
          This is an overloaded member function, provided for convenience.
 void start(java.lang.String program, java.util.List arguments)
          Starts the program program in a new process, passing the command line arguments in arguments.
 void start(java.lang.String program, java.util.List arguments, QIODevice.OpenMode mode)
          Starts the program program in a new process, passing the command line arguments in arguments.
 void start(java.lang.String program, java.util.List arguments, QIODevice.OpenModeFlag[] mode)
          This is an overloaded method provided for convenience.
 void start(java.lang.String program, QIODevice.OpenMode mode)
          This is an overloaded member function, provided for convenience.
 void start(java.lang.String program, QIODevice.OpenModeFlag[] mode)
          This is an overloaded method provided for convenience.
static boolean startDetached(java.lang.String program)
          This is an overloaded member function, provided for convenience.
static boolean startDetached(java.lang.String program, java.util.List arguments)
          Starts the program program with the given arguments in a new process, and detaches from it.
static QProcess.DetachedProcessInfo startDetached(java.lang.String program, java.util.List arguments, java.lang.String workingDirectory)
           
 QProcess.ProcessState state()
          Returns the current state of the process.
static java.util.List systemEnvironment()
          Returns the environment of the calling process as a list of key=value pairs.
 void terminate()
          Attempts to terminate the process.
 boolean waitForFinished()
          Blocks until the process has finished and the finished() signal has been emitted, or until msecs milliseconds have passed.
 boolean waitForFinished(int msecs)
          Blocks until the process has finished and the finished() signal has been emitted, or until msecs milliseconds have passed.
 boolean waitForStarted()
          Blocks until the process has started and the started() signal has been emitted, or until msecs milliseconds have passed.
 boolean waitForStarted(int msecs)
          Blocks until the process has started and the started() signal has been emitted, or until msecs milliseconds have passed.
 java.lang.String workingDirectory()
          If QProcess has been assigned a working directory, this function returns the working directory that the QProcess will enter before the program has started.
 
Methods inherited from class com.trolltech.qt.core.QIODevice
atEnd, bytesAvailable, bytesToWrite, canReadLine, close, errorString, getByte, isOpen, isReadable, isSequential, isTextModeEnabled, isWritable, open, open, openMode, peek, peek, pos, putByte, read, read, readAll, readData, readLine, readLine, readLine, readLineData, reset, seek, setErrorString, setOpenMode, setOpenMode, setTextModeEnabled, size, ungetByte, waitForBytesWritten, waitForReadyRead, write, write, writeData
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Field Detail

error

public final QSignalEmitter.Signal1 error

This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <com.trolltech.qt.core.QProcess$ProcessError(named: error)>:

This signal is emitted when an error occurs with the process. The specified error describes the type of error that occurred.


finished

public final QSignalEmitter.Signal1 finished

This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <java.lang.Integer(named: exitCode)>:

This is an overloaded member function, provided for convenience.

Use finished(int exitCode, QProcess::ExitStatus status) instead.


finishedWithStatusCode

public final QSignalEmitter.Signal2 finishedWithStatusCode

This signal takes 2 generic argument(s). We list their type and the name they go by in the description of this signal. <java.lang.Integer(named: exitCode), >:

This is an overloaded member function, provided for convenience.

Use finished(int exitCode, QProcess::ExitStatus status) instead.


readyReadStandardError

public final QSignalEmitter.Signal0 readyReadStandardError
This signal is emitted when the process has made new data available through its standard error channel (stderr). It is emitted regardless of the current read channel.

See also:
readAllStandardError(), and readChannel().


readyReadStandardOutput

public final QSignalEmitter.Signal0 readyReadStandardOutput
This signal is emitted when the process has made new data available through its standard output channel (stdout). It is emitted regardless of the current read channel.

See also:
readAllStandardOutput(), and readChannel().


started

public final QSignalEmitter.Signal0 started
This signal is emitted by QProcess when the process has started, and state() returns Running .


stateChanged

public final QSignalEmitter.Signal1 stateChanged

This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <com.trolltech.qt.core.QProcess$ProcessState(named: newState)>:

This signal is emitted whenever the state of QProcess changes. The newState argument is the state QProcess changed to.

Constructor Detail

QProcess

public QProcess()
Constructs a QProcess object with the given parent.


QProcess

public QProcess(QObject parent)
Constructs a QProcess object with the given parent.

Method Detail

closeReadChannel

public final void closeReadChannel(QProcess.ProcessChannel channel)
Closes the read channel channel. After calling this function, QProcess will no longer receive data on the channel. Any data that has already been received is still available for reading.

Call this function to save memory, if you are not interested in the output of the process.

See also:
closeWriteChannel(), and setReadChannel().


closeWriteChannel

public final void closeWriteChannel()
Schedules the write channel of QProcess to be closed. The channel will close once all data has been written to the process. After calling this function, any attempts to write to the process will fail.

Closing the write channel is necessary for programs that read input data until the channel has been closed. For example, the program "more" is used to display text data in a console on both Unix and Windows. But it will not display the text data until QProcess's write channel has been closed. Example:

        QProcess more = new QProcess();
        more.start("more");
        more.write(new QByteArray("Text to display"));
        more.closeWriteChannel();
        // QProcess will emit readyRead() once "more" starts printing
The write channel is implicitly opened when start() is called.

See also:
closeReadChannel().


environment

public final java.util.List environment()
Returns the environment that QProcess will use when starting a process, or an empty QStringList if no environment has been set using setEnvironment(). If no environment has been set, the environment of the calling process will be used.

Note: The environment settings are ignored on Windows CE, as there is no concept of an environment.

See also:
setEnvironment(), and systemEnvironment().


error

public final QProcess.ProcessError error()
Returns the type of error that occurred last.

See also:
state().


exitCode

public final int exitCode()
Returns the exit code of the last process that finished.


exitStatus

public final QProcess.ExitStatus exitStatus()
Returns the exit status of the last process that finished.

On Windows, if the process was terminated with TerminateProcess() from another application this function will still return NormalExit unless the exit code is less than 0.


kill

public final void kill()
Kills the current process, causing it to exit immediately.

On Windows, kill() uses TerminateProcess, and on Unix and Mac OS X, the SIGKILL signal is sent to the process.

See also:
terminate().


processChannelMode

public final QProcess.ProcessChannelMode processChannelMode()
Returns the channel mode of the QProcess standard output and standard error channels.

See also:
setProcessChannelMode(), setReadChannelMode(), ProcessChannelMode , and setReadChannel().


readAllStandardError

public final QByteArray readAllStandardError()
Regardless of the current read channel, this function returns all data available from the standard error of the process as a QByteArray.

See also:
readyReadStandardError() , readAllStandardOutput(), readChannel(), and setReadChannel().


readAllStandardOutput

public final QByteArray readAllStandardOutput()
Regardless of the current read channel, this function returns all data available from the standard output of the process as a QByteArray.

See also:
readyReadStandardOutput() , readAllStandardError(), readChannel(), and setReadChannel().


readChannel

public final QProcess.ProcessChannel readChannel()
Returns the current read channel of the QProcess.

See also:
setReadChannel().


setEnvironment

public final void setEnvironment(java.util.List environment)
Sets the environment that QProcess will use when starting a process to the environment specified which consists of a list of key=value pairs.

For example, the following code adds the C:\\BIN directory to the list of executable paths (PATHS) on Windows:

        QProcess process = new QProcess();
        List<String> env = QProcess.systemEnvironment();
        env.add("TMPDIR=C:\\MyApp\\temp"); // Add an environment variable
        for (String str : env)
            str.replaceAll("^PATH=(.*)", "PATH=\\1;C:\\Bin");
        process.setEnvironment(env);
        process.start("myapp");
        

See also:
environment(), and systemEnvironment().


setProcessChannelMode

public final void setProcessChannelMode(QProcess.ProcessChannelMode mode)
Sets the channel mode of the QProcess standard output and standard error channels to the mode specified. This mode will be used the next time start() is called. For example:
        QProcess builder = new QProcess();
        builder.setProcessChannelMode(QProcess.ProcessChannelMode.MergedChannels);

        List<String> arguments = new Vector<String>();
        arguments.add("-j2");

        builder.start("make", arguments);

        if (!builder.waitForFinished())
            System.err.println("Make failed:" + builder.errorString());
        else
            System.err.println("Make output:" + builder.readAll());

See also:
processChannelMode(), readChannelMode(), ProcessChannelMode , and setReadChannel().


setProcessState

protected final void setProcessState(QProcess.ProcessState state)
Sets the current state of the QProcess to the state specified.

See also:
state().


setReadChannel

public final void setReadChannel(QProcess.ProcessChannel channel)
Sets the current read channel of the QProcess to the given channel. The current input channel is used by the functions read(), readAll(), readLine(), and getChar(). It also determines which channel triggers QProcess to emit readyRead() .

See also:
readChannel().


setStandardErrorFile

public final void setStandardErrorFile(java.lang.String fileName,
                                       QIODevice.OpenModeFlag[] mode)
This is an overloaded method provided for convenience.


setStandardErrorFile

public final void setStandardErrorFile(java.lang.String fileName)
Redirects the process' standard error to the file fileName. When the redirection is in place, the standard error read channel is closed: reading from it using read() will always fail, as will readAllStandardError(). The file will be appended to if mode is Append, otherwise, it will be truncated.

See setStandardOutputFile() for more information on how the file is opened.

Note: if setProcessChannelMode() was called with an argument of QProcess::MergedChannels , this function has no effect.

See also:
setStandardInputFile(), setStandardOutputFile(), and setStandardOutputProcess().


setStandardErrorFile

public final void setStandardErrorFile(java.lang.String fileName,
                                       QIODevice.OpenMode mode)
Redirects the process' standard error to the file fileName. When the redirection is in place, the standard error read channel is closed: reading from it using read() will always fail, as will readAllStandardError(). The file will be appended to if mode is Append, otherwise, it will be truncated.

See setStandardOutputFile() for more information on how the file is opened.

Note: if setProcessChannelMode() was called with an argument of QProcess::MergedChannels , this function has no effect.

See also:
setStandardInputFile(), setStandardOutputFile(), and setStandardOutputProcess().


setStandardInputFile

public final void setStandardInputFile(java.lang.String fileName)
Redirects the process' standard input to the file indicated by fileName. When an input redirection is in place, the QProcess object will be in read-only mode (calling write() will result in error).

If the file fileName does not exist at the moment start() is called or is not readable, starting the process will fail.

Calling setStandardInputFile() after the process has started has no effect.

See also:
setStandardOutputFile(), setStandardErrorFile(), and setStandardOutputProcess().


setStandardOutputFile

public final void setStandardOutputFile(java.lang.String fileName,
                                        QIODevice.OpenModeFlag[] mode)
This is an overloaded method provided for convenience.


setStandardOutputFile

public final void setStandardOutputFile(java.lang.String fileName)
Redirects the process' standard output to the file fileName. When the redirection is in place, the standard output read channel is closed: reading from it using read() will always fail, as will readAllStandardOutput().

If the file fileName doesn't exist at the moment start() is called, it will be created. If it cannot be created, the starting will fail.

If the file exists and mode is QIODevice::Truncate , the file will be truncated. Otherwise (if mode is QIODevice::Append ), the file will be appended to.

Calling setStandardOutputFile() after the process has started has no effect.

See also:
setStandardInputFile(), setStandardErrorFile(), and setStandardOutputProcess().


setStandardOutputFile

public final void setStandardOutputFile(java.lang.String fileName,
                                        QIODevice.OpenMode mode)
Redirects the process' standard output to the file fileName. When the redirection is in place, the standard output read channel is closed: reading from it using read() will always fail, as will readAllStandardOutput().

If the file fileName doesn't exist at the moment start() is called, it will be created. If it cannot be created, the starting will fail.

If the file exists and mode is QIODevice::Truncate , the file will be truncated. Otherwise (if mode is QIODevice::Append ), the file will be appended to.

Calling setStandardOutputFile() after the process has started has no effect.

See also:
setStandardInputFile(), setStandardErrorFile(), and setStandardOutputProcess().


setStandardOutputProcess

public final void setStandardOutputProcess(QProcess destination)
Pipes the standard output stream of this process to the destination process' standard input.

The following shell command:

        command1 | command2
Can be accomplished with QProcesses with the following code:
        QProcess process1 = new QProcess();
        QProcess process2 = new QProcess();

        process1.setStandardOutputProcess(process2);

        process1.start("command1");
        process2.start("command2");


setWorkingDirectory

public final void setWorkingDirectory(java.lang.String dir)
Sets the working directory to dir. QProcess will start the process in this directory. The default behavior is to start the process in the working directory of the calling process.

See also:
workingDirectory(), and start().


start

public final void start(java.lang.String program,
                        QIODevice.OpenModeFlag[] mode)
This is an overloaded method provided for convenience.


start

public final void start(java.lang.String program)
This is an overloaded member function, provided for convenience.

Starts the program program in a new process. program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces. For example:

        QProcess process = new QProcess();
        process.start("del /s *.txt");
        // same as process.start("del", List<String>() << "/s" << "*.txt");
        // ...
The program string can also contain quotes, to ensure that arguments containing spaces are correctly supplied to the new process. For example:
        QProcess process = new QProcess();
        process.start("dir \"My Documents\"");
Note that, on Windows, quotes need to be both escaped and quoted. For example, the above code would be specified in the following way to ensure that "My Documents" is used as the argument to the dir executable:
        QProcess process = new QProcess();
        process.start("dir \"\"\"My Documents\"\"\"");
The OpenMode is set to mode.


start

public final void start(java.lang.String program,
                        QIODevice.OpenMode mode)
This is an overloaded member function, provided for convenience.

Starts the program program in a new process. program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces. For example:

        QProcess process = new QProcess();
        process.start("del /s *.txt");
        // same as process.start("del", List<String>() << "/s" << "*.txt");
        // ...
The program string can also contain quotes, to ensure that arguments containing spaces are correctly supplied to the new process. For example:
        QProcess process = new QProcess();
        process.start("dir \"My Documents\"");
Note that, on Windows, quotes need to be both escaped and quoted. For example, the above code would be specified in the following way to ensure that "My Documents" is used as the argument to the dir executable:
        QProcess process = new QProcess();
        process.start("dir \"\"\"My Documents\"\"\"");
The OpenMode is set to mode.


start

public final void start(java.lang.String program,
                        java.util.List arguments,
                        QIODevice.OpenModeFlag[] mode)
This is an overloaded method provided for convenience.


start

public final void start(java.lang.String program,
                        java.util.List arguments)
Starts the program program in a new process, passing the command line arguments in arguments. QProcess will immediately enter the Starting state. If the process starts successfully, QProcess will emit started(); otherwise, error() will be emitted.

On Windows, arguments that contain spaces are wrapped in quotes.

Note: processes are started asynchronously, which means the started() and error() signals may be delayed. Call waitForStarted() to make sure the process has started (or has failed to start) and those signals have been emitted.


start

public final void start(java.lang.String program,
                        java.util.List arguments,
                        QIODevice.OpenMode mode)
Starts the program program in a new process, passing the command line arguments in arguments. The OpenMode is set to mode. QProcess will immediately enter the Starting state. If the process starts successfully, QProcess will emit started() ; otherwise, error() will be emitted.

Note that arguments that contain spaces are not passed to the process as separate arguments.

Windows: Arguments that contain spaces are wrapped in quotes.

Note: Processes are started asynchronously, which means the started() and error() signals may be delayed. Call waitForStarted() to make sure the process has started (or has failed to start) and those signals have been emitted.

See also:
pid(), started() , and waitForStarted().


state

public final QProcess.ProcessState state()
Returns the current state of the process.

See also:
stateChanged() , and error().


terminate

public final void terminate()
Attempts to terminate the process.

The process may not exit as a result of calling this function (it is given the chance to prompt the user for any unsaved files, etc).

On Windows, terminate() posts a WM_CLOSE message to all toplevel windows of the process and then to the main thread of the process itself. On Unix and Mac OS X the SIGTERM signal is sent.

Console applications on Windows that do not run an event loop, or whose event loop does not handle the WM_CLOSE message, can only be terminated by calling kill().

See also:
kill().


waitForFinished

public final boolean waitForFinished()
Blocks until the process has finished and the finished() signal has been emitted, or until msecs milliseconds have passed.

Returns true if the process finished; otherwise returns false (if the operation timed out or if an error occurred).

This function can operate without an event loop. It is useful when writing non-GUI applications and when performing I/O operations in a non-GUI thread.

Warning: Calling this function from the main (GUI) thread might cause your user interface to freeze.

If msecs is -1, this function will not time out.

See also:
finished() , waitForStarted(), waitForReadyRead(), and waitForBytesWritten().


waitForFinished

public final boolean waitForFinished(int msecs)
Blocks until the process has finished and the finished() signal has been emitted, or until msecs milliseconds have passed.

Returns true if the process finished; otherwise returns false (if the operation timed out or if an error occurred).

This function can operate without an event loop. It is useful when writing non-GUI applications and when performing I/O operations in a non-GUI thread.

Warning: Calling this function from the main (GUI) thread might cause your user interface to freeze.

If msecs is -1, this function will not time out.

See also:
finished() , waitForStarted(), waitForReadyRead(), and waitForBytesWritten().


waitForStarted

public final boolean waitForStarted()
Blocks until the process has started and the started() signal has been emitted, or until msecs milliseconds have passed.

Returns true if the process was started successfully; otherwise returns false (if the operation timed out or if an error occurred).

This function can operate without an event loop. It is useful when writing non-GUI applications and when performing I/O operations in a non-GUI thread.

Warning: Calling this function from the main (GUI) thread might cause your user interface to freeze.

If msecs is -1, this function will not time out.

See also:
started() , waitForReadyRead(), waitForBytesWritten(), and waitForFinished().


waitForStarted

public final boolean waitForStarted(int msecs)
Blocks until the process has started and the started() signal has been emitted, or until msecs milliseconds have passed.

Returns true if the process was started successfully; otherwise returns false (if the operation timed out or if an error occurred).

This function can operate without an event loop. It is useful when writing non-GUI applications and when performing I/O operations in a non-GUI thread.

Warning: Calling this function from the main (GUI) thread might cause your user interface to freeze.

If msecs is -1, this function will not time out.

See also:
started() , waitForReadyRead(), waitForBytesWritten(), and waitForFinished().


workingDirectory

public final java.lang.String workingDirectory()
If QProcess has been assigned a working directory, this function returns the working directory that the QProcess will enter before the program has started. Otherwise, (i.e., no directory has been assigned,) an empty string is returned, and QProcess will use the application's current working directory instead.

See also:
setWorkingDirectory().


setupChildProcess

protected void setupChildProcess()
This function is called in the child process context just before the program is executed on Unix or Mac OS X (i. ., after fork(), but before execve()). Reimplement this function to do last minute initialization of the child process. Example:
        This code is not relevant for Qt Jambi.
        class SandboxProcess extends QProcess
        {

            protected void setupChildProcess()
            {
            // Drop all privileges in the child process, and enter
            // a chroot jail.
                if (QSysInfo.operatingSystem() == QSysInfo.OS_LINUX) {
                    setgroups(0, 0);
                    chroot("/etc/safe");
                    chdir("/");
                    setgid(safeGid);
                    setuid(safeUid);
                }
            }
        }

You cannot exit the process (by calling exit(), for instance) from this function. If you need to stop the program before it starts execution, your workaround is to emit finished() and then call exit().

Warning: This function is called by QProcess on Unix and Mac OS X only. On Windows, it is not called.


execute

public static int execute(java.lang.String program)
This is an overloaded member function, provided for convenience.

Starts the program program in a new process. program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces.


execute

public static int execute(java.lang.String program,
                          java.util.List arguments)
Starts the program program with the arguments arguments in a new process, waits for it to finish, and then returns the exit code of the process. Any data the new process writes to the console is forwarded to the calling process.

The environment and working directory are inherited by the calling process.

On Windows, arguments that contain spaces are wrapped in quotes.


startDetached

public static boolean startDetached(java.lang.String program)
This is an overloaded member function, provided for convenience.

Starts the program program in a new process. program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces.

The program string can also contain quotes, to ensure that arguments containing spaces are correctly supplied to the new process.


startDetached

public static boolean startDetached(java.lang.String program,
                                    java.util.List arguments)
Starts the program program with the given arguments in a new process, and detaches from it. Returns true on success; otherwise returns false. If the calling process exits, the detached process will continue to live.

Note that arguments that contain spaces are not passed to the process as separate arguments.

Unix: The started process will run in its own session and act like a daemon.

Windows: Arguments that contain spaces are wrapped in quotes. The started process will run as a regular standalone process.


systemEnvironment

public static java.util.List systemEnvironment()
Returns the environment of the calling process as a list of key=value pairs. Example:
        List<String> environment = QProcess.systemEnvironment();
        // environment = {"PATH=/usr/bin:/usr/local/bin",
        //               "USER=greg", "HOME=/home/greg"}

See also:
environment(), and setEnvironment().


startDetached

public static QProcess.DetachedProcessInfo startDetached(java.lang.String program,
                                                         java.util.List arguments,
                                                         java.lang.String workingDirectory)