Question

I am developing an application for work that allows the users to quickly set environment variables on a terminal basis. By setting the path in each terminal we ensure files with the same name in different directories aren’t causing application testing to be problematic. I am Using Qt to build the program which is c++ based and all the datatypes are foundationally the same.

I am using the following code to invoke commands in the terminal from which the application launches from using system(). I can run commands into the bash just fine with code; however, I run into a problem when I attempt to use a command with arguments. This is probably why source doesn’t seem to work right as the source command is followed by the filename. It would appear that I drop the argument appended after the bash command.

My Code:

void assignTerminalToPath(QString path)
{
    QString data = "";
    QString currentUsersHomeDirectory = QDir::homePath();
    QString tmpScriptLocation = currentUsersHomeDirectory;
    QByteArray ba;
    tmpScriptLocation += "/.tmpSourceFile";
    QFile tmpSourceFile(tmpScriptLocation);
    if(tmpSourceFile.open(QFile::WriteOnly | QFile::Truncate))
    {
        QTextStream output(&tmpSourceFile);
        data.append("export PATH=.:");
        data.append(path);
        data.append(":$PATH");
        output << QString("#!/bin/bash\n");
        output << data;
        tmpSourceFile.close();
    }
    data.clear();
    data.append("/bin/bash -c source ");
    data.append(tmpScriptLocation);
    ba = data.toLatin1();
    const char *cStr = ba.data();
    system(cStr);
}

Perhaps I’m not referencing bash correctly and I need something outside of -c?

Reference Execute shell/bash command using C/C++

Thanks for any help in advance!

Answer 1

source is not a program that you can call, it is embedded bash command. It is designed to be processed by bash without invoking another copy of bash, such that environment variables can be changed in current bash copy.

However, you cannot call source as part of system(). And even if you did succeed at that, its effects to change environment variables would be completely lost for caller app once system() has returned.