Currently I'm trying to understand capabilities in Linux by reading http://man7.org/linux/man-pages/man7/capabilities.7.html

I created a small C++ application with the capability CAP_DAC_READ_SEARCH+eip

The capability works fine for the application. But I have a system() call inside

system("cat /dev/mtdX > targetFile"); 

How I can inherit the capability to this call?

Edit:

I know that system() is driven by fork() + execl(). In the documentation is mentioned, that with fork() the child process get the same capabilities as the parent process. But why is the read capability not inherited?