a.connect( this, SLOT(show()), this, SLOT( smb_conf()));

#include <QApplication>
#include "share.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    share *dialog = new share;
 
    dialog->show();
    return app.exec();
}

#ifndef SHARE_H
#define SHARE_H

#include "ui_share.h"


class share : public QDialog, private Ui::dialogs
{
    Q_OBJECT

public:
    share(QDialog *parent = 0);

public slots:
    void getPath();
    void smb_conf();
};

#endif

#include <QtGui>
#include "share.h"

share::share(QDialog *parent)
{
    setupUi(this);
    
    connect( pushButton_2, SIGNAL( clicked() ), this, SLOT( getPath() ) );
}

void share::getPath() {
    QString path;
    
    path = QFileDialog::getExistingDirectory(
        this,
        "Choose a folder",
    QDir::currentPath()
    );
 
lineEdit_3->setText( path );
    
}


void share::smb_conf () {
        
    int unsigned i = 0, linecounter = 0;
    QString tx;

    QString name[30];
    QFile fa ("/home/tintix/Desktop/smb.conf");

        ---------//Что-то происходит//--------------
      
        lineEdit->setText(name[0]);
}