管道（或命令链）与QProcess [英] Piping (or command chaining) with QProcess

问题描述

我使用的是Qt和bash，需要执行：

I'm using Qt and bash over it, need to execute something like:

bash: cat file | grep string

在Qt中：

QString cmd = "cat file | grep string";
QProcess *process = new QProcess;
process->start(cmd);
process->waitForBytesWritten();
process->waitForFinished();
qDebug() << process->readAll();

问题是在管道（|），并且进程无返回。如果没有（|），如

The problem is in pipe ("|"), and process returs nothing. If there is no ("|"), like

"cat file" 

一切正常。
我试过smth。如

everything is ok. I tried smth. like

"cat file \\| grep string", 
"cat file \| grep string" 

但结果是一样的。如果我复制命令并运行它在bash一切正常。

but result is the same. If I copy the command and run it in bash everything is ok.

QString::toAscii().data()

和其他转换也有不好的结果。

and other transforms also have bad result.

推荐答案

问题是你不能使用QProcess运行系统命令，而只能运行一个进程。因此，解决方法是将您的命令作为bash的参数传递：

The problem is you cannot run a system command with QProcess, but only a single process. So the workaround will be to pass your command as an argument to bash:

process.start("bash", QStringList() << "-c" << "cat file | grep string");

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