C / C++ / MFC

const char *command = "rfkill list > textEdit";
system(command)
// or even just
system("rfkill list > textEdit");

    const char *command = "rfkill list ";
    outputs so console  OK 
     qDebug() <<" system call result " << QString::number(system(command) );
     command = "rfkill list  >> /tmp/temp";
outputs to temporary file OK 
     qDebug() <<" system call result " << QString::number(system(command) );
     command = "rfkill list |tee >> /tmp/temp";
no console output , may have added to test file - not checked 
     qDebug() <<" system call result " << QString::number(system(command) );
     command = "rfkill list >> textEdit";
no output anywhere 
     qDebug() <<" system call result " << QString::number(system(command) );

TEST  set data 
0: hci0: Bluetooth
	Soft blocked: no
	Hard blocked: no
2: hci1: Bluetooth
	Soft blocked: no
	Hard blocked: no
 system call result  "0"
 system call result  "0"
 system call result  "0"
 system call result  "0"

SYNOPSIS
       tee [OPTION]... [FILE]...

rfkill list | tee tempFile

11:19:00: Running steps for project HCI_VERSION_622...
11:19:00: Configuration unchanged, skipping qmake step.

11:19:00: Starting: "/usr/bin/make" -j4

/home/qy/Qt/6.2.2/gcc_64/bin/qmake -o Makefile ../HCI_VERSION_622/HCI_VERSION_622.pro -spec linux-g++ CONFIG+=debug CONFIG+=qml_debug

rm -f libHCI_VERSION_622.so.1.0.0 libHCI_VERSION_622.so libHCI_VERSION_622.so.1 libHCI_VERSION_622.so.1.0

g++ -Wl,-rpath,/home/qy/Qt/6.2.2/gcc_64/lib -Wl,-rpath-link,/home/qy/Qt/6.2.2/gcc_64/lib -shared -Wl,-soname,libHCI_VERSION_622.so.1 -o libHCI_VERSION_622.so.1.0.0 main.o mainwindow_hci_v_622.o moc_mainwindow_hci_v_622.o  /home/qy/Qt/6.2.2/gcc_64/lib/libQt6Widgets.so /home/qy/Qt/6.2.2/gcc_64/lib/libQt6Gui.so /home/qy/Qt/6.2.2/gcc_64/lib/libQt6Concurrent.so /home/qy/Qt/6.2.2/gcc_64/lib/libQt6Core.so -lpthread -lGL

ln -s libHCI_VERSION_622.so.1.0.0 libHCI_VERSION_622.so
ln -s libHCI_VERSION_622.so.1.0.0 libHCI_VERSION_622.so.1
ln -s libHCI_VERSION_622.so.1.0.0 libHCI_VERSION_622.so.1.0

11:19:02: The process "/usr/bin/make" exited normally.
11:19:02: Elapsed time: 00:02.

Member 14968771 wrote:

-shared -Wl,-soname,libHCI_VERSION_622.so.1 -o libHCI_VERSION_622.so.1.0.0 main.o mainwindow_hci_v_622.o moc_mainwindow_hci_v_622.o

$ cat bad_alloc.cpp
 #include <iostream>

int main()
{
    size_t lim = 2;
    while(true)
    {
        int *arr = new int[lim];
        delete[] arr;
        lim *= 2;
    }
    return 0;
}
$ # That will eventually try to allocate too much memory
$ # compile with gdb, in 32 bit mode to get a quick crash
$ g++ -m32 -ggdb  bad_alloc.cpp -o bad_alloc
$ # debug the program
$ gdb bad_alloc
 #
 # GDB startup messages snipped out
 #
Reading symbols from bad_alloc...
(gdb) run
Starting program: /home/ebacon/tmp/c++/bad_alloc 
terminate called after throwing an instance of 'std::bad_array_new_length'
  what():  std::bad_array_new_length

Program received signal SIGABRT, Aborted.
0xf7fce559 in __kernel_vsyscall ()
Missing separate debuginfos, use: dnf debuginfo-install glibc-2.32-10.fc33.i686 libgcc-10.3.1-1.fc33.i686
(gdb) # take a look at the backtrace
(gdb) bt
 #0  0xf7fce559 in __kernel_vsyscall ()
 #1  0xf7d2759a in raise () from /lib/libc.so.6
 #2  0xf7d0f3d0 in abort () from /lib/libc.so.6
 #3  0x0804c829 in __gnu_cxx::__verbose_terminate_handler() [clone .cold] ()
 #4  0x080dee78 in __cxxabiv1::__terminate(void (*)()) ()
 #5  0x080def01 in std::terminate() ()
 #6  0x0804dbb0 in __cxa_throw ()
 #7  0x0804a7ee in __cxa_throw_bad_array_new_length ()
 #8  0x0804d9f7 in main () at bad_alloc.cpp:8
(gdb) # all the frames except the last are part of the STL, 
(gdb) # so we're probably only interested in frame 8 
(gdb) frame 8
 #8  0x0804d9f7 in main () at bad_alloc.cpp:8
8               int *arr = new int[lim];
(gdb) # The 8 in the line above refers to line 8 of the source 
(gdb) # print the value of lim 
(gdb) p lim
$1 = 536870912
(gdb) quit
A debugging session is active.
        Inferior 1 [process 3076940] will be killed.
Quit anyway? (y or n) y
$

QProcess::execute("hcitool", "-i chio scan --flush");

<pre>OProcess.start("/bin/sh", QStringList() << "-c" << "hcitool -i hci0 scan --flush  | tee >> /tmp/temp");                   no tee ourput to console - not that important 
qDebug() << OProcess.state();    returns "process starting" expected 
qDebug() << OProcess.state();    returns "process starting" sort of expected
OProcess.waitForFinished();
//OProcess.state();
qDebug() << OProcess.state();    return process  not running expected

OProcess.execute("hcitool-i hci0 scan --flush >>/tmp/temp");
qDebug() << OProcess.state(); return process  not running not surprised 
OProcess.waitForFinished();
OProcess.state();
qDebug() << OProcess.state();  return process  not running obvious