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Read sysctl Key (sys.ctlbyname)

Declaration​

data = sys.ctlbyname(key)

Parameters​

  • key
    String. Full sysctl key name, for example kern.boottime or hw.memsize.

Returns​

  • data
    String. Raw byte data returned by the key. Returns nil when the key cannot be read.

Description​

Calls the underlying sysctlbyname to fetch kernel or hardware runtime parameters.
Use this to retrieve sysctl values, inspect kernel state, or capture metrics. The raw data often needs additional unpacking.

Examples​

local raw = sys.ctlbyname('hw.machine')
if type(raw) == 'string' then
    nLog('Device type: '..raw:gsub('%z+$', ''))
else
    nLog('Failed to read hw.machine')
end

local sec, usec = string.unpack('li', sys.ctlbyname('kern.boottime'))
nLog('Seconds since boot', os.time() - sec)