使用 QProcess 管道(或命令链)

Piping (or command chaining) with QProcess(使用 QProcess 管道(或命令链))

问题描述

我正在使用 Qt 并对其进行 bash，需要执行如下操作:

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();

问题出在管道(|")中，进程没有返回任何内容.如果没有(|")，比如

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

"cat file" 

一切正常.我试过了.喜欢

everything is ok. I tried smth. like

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

但结果是一样的.如果我复制命令并在 bash 中运行它，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

问题是您不能使用 QProcess 运行系统命令，而只能运行单个进程.因此，解决方法是将您的命令作为参数传递给 bash:

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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