Linux c++: apis vs /proc files?

Question

Im working on an app to collect and send various bits of system info (partition space/free, laptop battery info, etc). Im not having much success getting this information in the form of direct c++ api.. though its all available via files in /proc (or similar).

So - I'm wondering whether reading/parsing these files in my c++ app is the appropriate way to get this info or should I keep trying to discover APIs? ( NOTE: I am working with statvfs ).

So far it looks like it's easier to gather this sort of info in Win32. Seems strange.

Answer 1

It is best practice by far to stick with an API in the following order of precedence.

• Your language API (not much help for you here, but say for strings, a C99 string function is better to use than a library string facility specified by a Posix or other OS standard.)

• Posix operating software APIs

• Documented kernel API's

• Undocumented kernel APIs (at least these will break, say, ioctl users if they change, so they probably won't change)

• /proc

• /dev/kmem, /dev/mem

There is no reason to believe that /proc trolling will be portable or even the same from release to release. Not every system will even have a /proc mounted!

Having said all that, it is much easier to just scrape stuff off of /proc and if it's the only available interface then you should go ahead and use it.qa

Finally, the ordering of the last two isn't completely clear, because /proc isn't available for a post-mortem kernel crash dump analysis, but tools that can peek in the core dump will still work.

Answer 2

I though that /proc was the API (everything is a file...)

Answer 3

As you have noticed, a lot of Linux systems information is in /proc. And you're correct that there often isn't a C API for retrieving that information (though there is usually a shell command if you're inclined to stick with bash instead of C++). In the worst-case scenario, you might be stuck parsing through /proc, though you might be able to get some sample code in the form of open-source shell commands for the particular item you want.