The QProcess class is used to start external programs and to communicate with them. 更多...
继承 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 (). Arguments are supplied as individual strings in a QStringList .
For example, the following code snippet runs the analog clock example in the Motif style on X11 platforms by passing strings containing "-style" and "motif" as two items in the list of arguments:
QObject *parent;
...
QString program = "./path/to/Qt/examples/widgets/analogclock";
QStringList arguments;
arguments << "-style" << "motif";
QProcess *myProcess = new QProcess(parent);
myProcess->start(program, arguments);
QProcess 然后进入 Starting state, and when the program has started, QProcess enters the 运行 状态并发射 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 ()，和 getChar ()。因为它继承 QIODevice , QProcess can also be used as an input source for QXmlReader ，或 for generating data to be uploaded using QFtp .
注意： On VxWorks, Windows CE and Symbian, reading and writing to a process is not supported.
当进程退出时，QProcess 重新进入 NotRunning state (the initial state), and emits finished ().
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 状态。
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 通过调用 setReadChannel ()。QProcess 发射 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 ()，或 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.
注意： On VxWorks, communicating via channels with a process is not supported.
注意： On Symbian, setting environment or working directory is not supported. The working directory will always be the private directory of the running process.
注意： On QNX, setting the working directory may cause all application threads, with the exception of the QProcess caller thread, to temporarily freeze, owing to a limitation in the 操作系统。
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.
以下范例运行 gzip to compress the string "Qt rocks!", without an event loop:
QProcess gzip;
gzip.start("gzip", QStringList() << "-c");
if (!gzip.waitForStarted())
return false;
gzip.write("Qt rocks!");
gzip.closeWriteChannel();
if (!gzip.waitForFinished())
return false;
QByteArray result = gzip.readAll();
某些 Windows 命令 (例如， 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 命令。
QProcess support is only available on RTP mode, and only a limited functionality is provided. When using QProcess to launch Qt applications, the launched application has to have the following code:
#include <signal.h>
Add following to your class constructor:
QObject.connect(QApplication.instance(), SIGNAL(unixSignal(int)), qApp, SLOT(quit())); QCoreApplication.watchUnixSignal(SIGKILL, true); QCoreApplication.watchUnixSignal(SIGTERM, true);
On Symbian, processes which use the functions kill () 或 terminate () must have the PowerMgmt platform security capability. If the client process lacks this capability, these functions will fail.
Platform security capabilities are added via the TARGET.CAPABILITY qmake variable.
此枚举描述不同退出状态为 QProcess .
| 常量 | 值 | 描述 |
|---|---|---|
| QProcess.NormalExit | 0 | 进程正常退出。 |
| QProcess.CrashExit | 1 | 进程崩溃。 |
另请参阅 exitStatus ().
This enum describes the process channels used by the running process. Pass one of these values to setReadChannel () 去设置 current read channel of QProcess .
| 常量 | 值 | 描述 |
|---|---|---|
| QProcess.StandardOutput | 0 | The standard output (stdout) of the running process. |
| QProcess.StandardError | 1 | The standard error (stderr) of the running process. |
另请参阅 setReadChannel ().
This enum describes the process channel modes of QProcess 。将这些值之一传递给 setProcessChannelMode () to set the current read channel mode.
| 常量 | 值 | 描述 |
|---|---|---|
| QProcess.SeparateChannels | 0 | QProcess manages the output of the running process, keeping standard output and standard error data in separate internal buffers. You can select the QProcess 's current read channel by calling setReadChannel (). This is the default channel mode of QProcess . |
| QProcess.MergedChannels | 1 | QProcess merges the output of the running process into the standard output channel ( stdout ). The standard error channel ( stderr ) will not receive any data. The standard output and standard error data of the running process are interleaved. |
| QProcess.ForwardedChannels | 2 | QProcess forwards the output of the running process onto the main process. Anything the child process writes to its standard output and standard error will be written to the standard output and standard error of the main process. |
另请参阅 setProcessChannelMode ().
This enum describes the different types of errors that are reported by QProcess .
| 常量 | 值 | 描述 |
|---|---|---|
| QProcess.FailedToStart | 0 | The process failed to start. Either the invoked program is missing, or you may have insufficient permissions to invoke the program. |
| QProcess.Crashed | 1 | The process crashed some time after starting successfully. |
| QProcess.Timedout | 2 | The last waitFor...() function timed out. The state of QProcess is unchanged, and you can try calling waitFor...() again. |
| QProcess.WriteError | 4 | An error occurred when attempting to write to the process. For example, the process may not be running, or it may have closed its input channel. |
| QProcess.ReadError | 3 | An error occurred when attempting to read from the process. For example, the process may not be running. |
| QProcess.UnknownError | 5 | An unknown error occurred. This is the default return value of error (). |
另请参阅 error ().
此枚举描述不同状态为 QProcess .
| 常量 | 值 | 描述 |
|---|---|---|
| QProcess.NotRunning | 0 | 进程未运行。 |
| QProcess.Starting | 1 | The process is starting, but the program has not yet been invoked. |
| QProcess.Running | 2 | The process is running and is ready for reading and writing. |
另请参阅 state ().
parent argument, if not None, causes self to be owned by Qt instead of PyQt.
构造 QProcess object with the given parent .
重实现自 QIODevice.atEnd ().
Returns true if the process is not running, and no more data is available for reading; otherwise returns false.
重实现自 QIODevice.bytesAvailable ().
重实现自 QIODevice.bytesToWrite ().
重实现自 QIODevice.canReadLine ().
此函数运转于当前读取通道。
另请参阅 readChannel () 和 setReadChannel ().
重实现自 QIODevice.close ().
Closes all communication with the process and kills it. After calling this function, QProcess will no longer emit readyRead ()，和 data can no longer be read or written.
关闭读取通道 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.
另请参阅 closeWriteChannel () 和 setReadChannel ().
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; more.start("more"); more.write("Text to display"); more.closeWriteChannel(); // QProcess will emit readyRead() once "more" starts printing
The write channel is implicitly opened when start () 被调用。
另请参阅 closeReadChannel ().
此函数被弃用。
Returns the environment that QProcess will use when starting a process, or 空 QStringList if no environment has been set using setEnvironment () 或 setEnvironmentHash(). If no environment has been set, the environment of the calling process will be used.
注意： The environment settings are ignored on Windows CE and Symbian, as there is no concept of an environment.
另请参阅 processEnvironment (), setEnvironment ()，和 systemEnvironment ().
返回最后发生的错误类型。
另请参阅 state ().
启动程序 program 采用自变量 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 from the calling process.
On Windows, arguments that contain spaces are wrapped in quotes.
If the process cannot be started, -2 is returned. If the process crashes, -1 is returned. Otherwise, the process' exit code is returned.
这是重载函数。
启动程序 program 在新的进程中。 program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces.
返回最后完成进程的退出代码。
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.
该函数在 Qt 4.1 引入。
重实现自 QIODevice.isSequential ().
This method is also a Qt slot with the C++ signature void kill() .
杀除当前进程，导致它立即退出。
On Windows, kill() uses TerminateProcess, and on Unix and Mac OS X, the SIGKILL signal is sent to the process.
On Symbian, this function requires platform security capability PowerMgmt . If absent, the process will panic with KERN-EXEC 46.
注意： Killing running processes from other processes will typically cause a panic in Symbian due to platform security.
另请参阅 Symbian Platform Security Requirements and terminate ().
Returns the native process identifier for the running process, if available. If no process is currently running, 0 is returned.
Returns the channel mode of the QProcess standard output and standard error channels.
该函数在 Qt 4.2 引入。
另请参阅 setProcessChannelMode (), ProcessChannelMode ，和 setReadChannel ().
Returns the environment that QProcess will use when starting a process, or an empty object if no environment has been set using setEnvironment () 或 setProcessEnvironment (). If no environment has been set, the environment of the calling process will be used.
注意： The environment settings are ignored on Windows CE, as there is no concept of an environment.
该函数在 Qt 4.6 引入。
另请参阅 setProcessEnvironment (), setEnvironment ()，和 QProcessEnvironment.isEmpty ().
Regardless of the current read channel, this function returns all data available from the standard error of the process as a QByteArray .
另请参阅 readyReadStandardError (), readAllStandardOutput (), readChannel ()，和 setReadChannel ().
Regardless of the current read channel, this function returns all data available from the standard output of the process as a QByteArray .
另请参阅 readyReadStandardOutput (), readAllStandardError (), readChannel ()，和 setReadChannel ().
返回当前读取通道为 QProcess .
另请参阅 setReadChannel ().
重实现自 QIODevice.readData ().
此函数被弃用。
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; QStringList env = QProcess.systemEnvironment(); env << "TMPDIR=C:\\MyApp\\temp"; // Add an environment variable env.replaceInStrings(QRegExp("^PATH=(.*)", Qt.CaseInsensitive), "PATH=\\1;C:\\Bin"); process.setEnvironment(env); process.start("myapp");
注意： This function is less efficient than the setProcessEnvironment () 函数。
另请参阅 environment (), setProcessEnvironment (), and systemEnvironment ().
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; builder.setProcessChannelMode(QProcess.MergedChannels); builder.start("make", QStringList() << "-j2"); if (!builder.waitForFinished()) qDebug() << "Make failed:" << builder.errorString(); else qDebug() << "Make output:" << builder.readAll();
该函数在 Qt 4.2 引入。
另请参阅 processChannelMode (), ProcessChannelMode ，和 setReadChannel ().
Sets the environment that QProcess will use when starting a process to the environment 对象。
For example, the following code adds the C:\\BIN directory to the list of executable paths ( PATHS ) on Windows and sets TMPDIR :
QProcess process; QProcessEnvironment env = QProcessEnvironment.systemEnvironment(); env.insert("TMPDIR", "C:\\MyApp\\temp"); // Add an environment variable env.insert("PATH", env.value("Path") + ";C:\\Bin"); process.setProcessEnvironment(env); process.start("myapp");
Note how, on Windows, environment variable names are case-insensitive.
该函数在 Qt 4.6 引入。
另请参阅 processEnvironment (), QProcessEnvironment.systemEnvironment (), and setEnvironment ().
设置当前状态为 QProcess 到 state 指定。
另请参阅 state ().
设置当前读取通道为 QProcess 到给定 channel 。 current input channel is used by the functions read (), readAll (), readLine ()，和 getChar (). It also determines which channel triggers QProcess to emit readyRead ().
另请参阅 readChannel ().
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.
见 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.
该函数在 Qt 4.2 引入。
另请参阅 setStandardInputFile (), setStandardOutputFile (), and setStandardOutputProcess ().
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.
该函数在 Qt 4.2 引入。
另请参阅 setStandardOutputFile (), setStandardErrorFile (), and setStandardOutputProcess ().
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 ， file will be truncated. Otherwise (if mode is QIODevice.Append ), the file will be appended to.
Calling setStandardOutputFile() after the process has started 不起作用。
该函数在 Qt 4.2 引入。
另请参阅 setStandardInputFile (), setStandardErrorFile (), and setStandardOutputProcess ().
Pipes the standard output stream of this process to the destination process' standard input.
以下 Shell 命令：
command1 | command2
Can be accomplished with QProcesses with the following code:
QProcess process1; QProcess process2; process1.setStandardOutputProcess(&process2); process1.start("command1"); process2.start("command2");
该函数在 Qt 4.2 引入。
This function is called in the child process context just before the program is executed on Unix or Mac OS X (i.e., after fork() , but before execve() ). Reimplement this function to do last minute initialization of the child process. 范例：
class SandboxProcess : public QProcess { ... protected: void setupChildProcess(); ... }; void SandboxProcess.setupChildProcess() { // Drop all privileges in the child process, and enter // a chroot jail. #if defined Q_OS_UNIX .setgroups(0, 0); .chroot("/etc/safe"); .chdir("/"); .setgid(safeGid); .setuid(safeUid); .umask(0); #endif }
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().
警告： 此函数被调用由 QProcess on Unix and Mac OS X only. On Windows and QNX, it is not called.
把工作目录设为 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.
注意： The working directory setting is ignored on Symbian; the private directory of the process is considered its working directory.
注意： On QNX, this may cause all application threads to temporarily freeze.
另请参阅 workingDirectory () 和 start ().
启动给定 program in a new process, if none is already running, passing the command line arguments in arguments 。 OpenMode is set to mode .
QProcess object will immediately enter the Starting state. If the process starts successfully, QProcess will emit started (); otherwise, error () will be emitted. If the QProcess object is already running a process, a warning may be printed at the console, and the existing process will continue running.
注意： Processes are started asynchronously, which means the started () 和 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.
注意： No further splitting of the arguments is performed.
Windows: Arguments that contain spaces are wrapped in quotes.
另请参阅 pid (), started ()，和 waitForStarted ().
这是重载函数。
启动程序 program in a new process, if one is not already running. 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; process.start("del /s *.txt"); // same as process.start("del", QStringList() << "/s" << "*.txt"); ...
program string can also contain quotes, to ensure that arguments containing spaces are correctly supplied to the new process. For example:
QProcess process; process.start("dir \"My Documents\"");
若 QProcess object is already running a process, a warning may be printed at the console, and the existing process will continue running.
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; process.start("dir \"\"\"My Documents\"\"\"");
OpenMode is 设为 mode .
启动程序 program 采用自变量 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.
The process will be started in the directory workingDirectory .
注意： On QNX, this may cause all application threads to temporarily freeze.
注意： On VxWorks, this will start RTP process always with priority set to 220.
If the function is successful then * pid is set to the process identifier of the started process.
启动程序 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.
注意： 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.
这是重载函数。
启动程序 program 在新的进程中。 program is a single string of text containing both the program name and its arguments. The arguments are separated by one or more spaces.
program string can also contain quotes, to ensure that arguments containing spaces are correctly supplied to the new process.
返回进程的当前状态。
另请参阅 stateChanged () 和 error ().
Returns the environment of the calling process as a list of key=value pairs. Example:
QStringList environment = QProcess.systemEnvironment(); // environment = {"PATH=/usr/bin:/usr/local/bin", // "USER=greg", "HOME=/home/greg"}
This function does not cache the system environment. Therefore, it's possible to obtain an updated version of the environment if low-level C library functions like setenv ot putenv have been called.
However, note that repeated calls to this function will recreate the list of environment variables, which is a non-trivial operation.
注意： 对于新代码，推荐使用 QProcessEnvironment.systemEnvironment ()
该函数在 Qt 4.1 引入。
另请参阅 QProcessEnvironment.systemEnvironment (), environment ()，和 setEnvironment ().
This method is also a Qt slot with the C++ signature void terminate() .
试图终止进程。
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 ().
On Symbian, this function requires platform security capability PowerMgmt . If absent, the process will panic with KERN-EXEC 46.
注意： Terminating running processes from other processes will typically cause a panic in Symbian due to platform security.
另请参阅 Symbian Platform Security Requirements and kill ().
重实现自 QIODevice.waitForBytesWritten ().
阻塞直到进程已完成且 finished () signal has been emitted, or until msecs 毫秒已过去。
Returns true if the process finished; otherwise returns false (若操作超时，若发生错误，或者若此 QProcess 已完成)。
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.
警告： Calling this function from the main (GUI) thread might cause your user interface to freeze.
若 msecs 为 -1，此函数不会超时。
另请参阅 finished (), waitForStarted (), waitForReadyRead (), and waitForBytesWritten ().
重实现自 QIODevice.waitForReadyRead ().
阻塞直到进程启动且 started () signal has been emitted, or until msecs 毫秒已过去。
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.
警告： Calling this function from the main (GUI) thread might cause your user interface to freeze.
若 msecs 为 -1，此函数不会超时。
另请参阅 started (), waitForReadyRead (), waitForBytesWritten ()，和 waitForFinished ().
若 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.
另请参阅 setWorkingDirectory ().
重实现自 QIODevice.writeData ().
This is the default overload of this signal.
This signal is emitted when an error occurs with the process. 指定 error describes the type of error that occurred.
This is the default overload of this signal.
This signal is emitted when the process finishes. exitCode is the exit code of the process, and exitStatus is the exit status. After the process has finished, the buffers in QProcess are still intact. You can still read any data that the process may have written before it finished.
另请参阅 exitStatus ().
This is the default overload of this signal.
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 .
另请参阅 readAllStandardError () 和 readChannel ().
This is the default overload of this signal.
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 .
另请参阅 readAllStandardOutput () and readChannel ().
This is the default overload of this signal.
此信号被发射由 QProcess 当此过程已开始，且 state () 返回 运行 .
This is the default overload of this signal.
此信号被发射每当状态为 QProcess 改变。 newState argument is the state QProcess 要改变。