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c++linuxposix

How to get source device of mount point in Linux programmatically?

I want to know which device mounted on some directory, like this:

auto device = get_device_of_mount_point("/path/to/some/dir");
std::cout << device << std::endl; // /dev/sda1
Solution

  • Here is a starting point, assuming C++17 is available:

    #include <string_view>
#include <fstream>
#include <optional>

std::optional<std::string> get_device_of_mount_point(std::string_view path)
{
   std::ifstream mounts{"/proc/mounts"};
   std::string mountPoint;
   std::string device;

   while (mounts >> device >> mountPoint)
   {
      if (mountPoint == path)
      {
         return device;
      }
   }

   return std::nullopt;
}

    You can use this function as follows.

    if (const auto device = get_device_of_mount_point("/"))
   std::cout << *device << "\n";
else
   std::cout << "Not found\n";