Strictly speaking, the question was about checking the lockedness of std::mutex directly. However, if encapsulating it in a new class is allowed, it’s very easy to do so: class mutex : public std::mutex { public: #ifndef NDEBUG void lock() { std::mutex::lock(); m_holder = std::this_thread::get_id(); } #endif // #ifndef NDEBUG #ifndef NDEBUG void unlock() { m_holder … Read more
You’ll need the Linux kernel sources in order to see the actual source of the system calls. Manual pages, if installed on your local system, only contain the documentation of the calls and not their source itself. Unfortunately for you, system calls aren’t stored in just one particular location in the whole kernel tree. This … Read more
Escape the .: sed ‘s/foo\./foo_/g’ file.php Example: ~$ cat test.txt foo.bar ~$ sed ‘s/foo\./foo_/g’ test.txt foo_bar
Update (Sep. 17, 2017): NVIDIA recently published an article detailing how to use OpenGL on headless systems, which is a very similar use case as the question describes. In summary: Link to libOpenGL.so and libEGL.so instead of libGL.so. (Your linker options should therefore be -lOpenGL -lEGL Call eglGetDisplay, then eglInitialize to initialize EGL. Call eglChooseConfig … Read more
Make file executable: chmod +x file Find location of perl: which perl This should return something like /bin/perl sometimes /usr/local/bin Then in the first line of your script add: #!”path”/perl with path from above e.g. #!/bin/perl Then you can execute the file ./file There may be some issues with the PATH, so you may want … Read more
The function getlogin_r() defined in unistd.h returns the username. See man getlogin_r for more information. Its signature is: int getlogin_r(char *buf, size_t bufsize); Needless to say, this function can just as easily be called in C or C++.
When you source the file, the assignments will be set but the variables are not exported unless the allexport option has been set. If you want all the variables to be exported, it is much simpler to use allexport and source the file than it is to read the file and use export explicitly. In … Read more
Apparently ubuntu and ruby don’t always catch dependencies like they should. From the first google hit (yeah, I clicked on this stack-overflow in place #2 before checking out the first result.) Navigate to the Ruby source and enter: sudo apt-get install libreadline5-dev cd ext/readline ruby extconf.rb make sudo make install So, if you’re on another … Read more
You won’t be able to open a server on port 80 without root privileges, this is a restriction on the OS level. So the only solution is to drop root privileges after you have opened the port. Here is a possible solution to drop root privileges in Python: Dropping privileges in Python. This is a … Read more
It is both complicated and differs from Unix to Unix variant. In Linux, for example, a system called Futex (Short for Fast Userspace Mutex) is used. In this system an atomic increment and test operation is performed on the mutex variable in user space. If the result of the operation indicates that there was no … Read more