Re: lua to read Linux, Solaris, FreeBSD kernel statistics

[David Favro <lua@...>]

On 02/21/2015 05:59 AM, Stefan Parvu wrote:
> Anyone, any ideas if there is anything done in Lua which can read /proc from Linux or
> sysctl interface from *BSD systems. Im interested to use Lua to fetch system statistics:
>
>   * cpu, memory utilization
>   * disk, nic utilization

I've always just coded up a quick parse of Linux /proc/foo when necessary, 
which is typically very easy using Lua string pattern matching.  If you want 
an API to return various utilization statistics that is platform-independent 
across Linux & BSD, I'm not aware of one but I think you could code it 
yourself very easily.

A Linux-only example below, works on 2.6 and 3.X kernels.  I'm not a VM 
expert, so your interpretation of what constitutes "free memory" may be 
different.

local function get_meminfo()
    local rv = {};
    local f = assert( io.open("/proc/meminfo","r") );
    for l in f:lines() do
        local key, n, units = l:match( "^([^:%s]+):%s+(%d+)%s?(%a?%a?)$" );
        if not key then error("Can't parse line: "..l); end
        n = tonumber(n);
        if units ~= "" then
            if units ~= "kB" then error("Unknown units: "..units); end
        else
            if n ~= 0 then n=n/1024; end
        end
        rv[key] = n;
    end
    f:close();
    return rv;
end;


local mi = get_meminfo();

local free = mi.Buffers + mi.Cached + mi.SwapCached;
print( "Free memory percent: ", 100*free/mi.MemTotal );