$ qmake && make 
/usr/lib/qt5/bin/uic mainwindow.ui -o ui_mainwindow.h
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o ExitHelper.o ExitHelper.cpp
ExitHelper.cpp: In static member function ‘static void ExitHelper::killClones(const QStringList&, int)’:
ExitHelper.cpp:59:13: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result]
   59 |  std::system(cmd.c_str());
      |  ~~~~~~~~~~~^~~~~~~~~~~~~
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o main.o main.cpp
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o mainwindow.o mainwindow.cpp
g++ -pipe -O2 -std=gnu++11 -Wall -W -dM -E -o moc_predefs.h /usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/dummy.cpp
/usr/lib/qt5/bin/moc -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB --include /tmp/test1/moc_predefs.h -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -I/tmp/test1 -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtWidgets -I/usr/include/x86_64-linux-gnu/qt5/QtGui -I/usr/include/x86_64-linux-gnu/qt5/QtCore -I/usr/include/c++/9 -I/usr/include/x86_64-linux-gnu/c++/9 -I/usr/include/c++/9/backward -I/usr/lib/gcc/x86_64-linux-gnu/9/include -I/usr/local/include -I/usr/include/x86_64-linux-gnu -I/usr/include ExitHelper.h -o moc_ExitHelper.cpp
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o moc_ExitHelper.o moc_ExitHelper.cpp
/usr/lib/qt5/bin/moc -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB --include /tmp/test1/moc_predefs.h -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -I/tmp/test1 -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtWidgets -I/usr/include/x86_64-linux-gnu/qt5/QtGui -I/usr/include/x86_64-linux-gnu/qt5/QtCore -I/usr/include/c++/9 -I/usr/include/x86_64-linux-gnu/c++/9 -I/usr/include/c++/9/backward -I/usr/lib/gcc/x86_64-linux-gnu/9/include -I/usr/local/include -I/usr/include/x86_64-linux-gnu -I/usr/include mainwindow.h -o moc_mainwindow.cpp
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o moc_mainwindow.o moc_mainwindow.cpp
g++ -Wl,-O1 -o test1 ExitHelper.o main.o mainwindow.o moc_ExitHelper.o moc_mainwindow.o   /usr/lib/x86_64-linux-gnu/libQt5Widgets.so /usr/lib/x86_64-linux-gnu/libQt5Gui.so /usr/lib/x86_64-linux-gnu/libQt5Core.so /usr/lib/x86_64-linux-gnu/libGL.so -lpthread   

$ ls -al test1
-rwxrwxr-x 1 aaa aaa 48896 янв 24 18:58 test1