The free command gets its information from /proc/meminfo. Performance-wise, it doesn't really matter if a few additional lines need to be parsed.
Hello, Thank you Florian. Actually, I already knew it's the same, I just thought that he could use the free command instead of parsing it himself. You're right. Performance-wise, it's pretty much the same.
Sorry, I didn't express myself properly. I didn't mean to criticize free. What I meant to say was that the time it takes to parse /proc/meminfo or free is negligible. It doesn't need to be any more efficient. free parses /proc/meminfo. libgtop parses /proc/meminfo. Querying the information probably takes much more time than parsing it.
Your suggestion to use free may indeed be useful if the original poster wants parsing to be slightly simpler and does not mind the additional dependency. My impression was that they considered parsing to be too inefficient.
there's also `sysinfo(2)` -- damjan