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While running ss -m command, which shows the memory usage of a socket. I got the following output.

ESTAB  0  0    mem:(r0,w0,f0,t0)

Can someone please explain me what these four character 'r' 'w' 'f' 't' denotes here?

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I'm no expert, but this seems to have come before here :… – chrskly Feb 7 '13 at 15:29

Per this excellent question and answer over on Unix & Linux:

r represents the read (inbound) buffer
w represents the write (outbound) buffer
f represents the "forward allocated memory" (memory available to the socket)
t represents the transmit queue (stuff waiting to be sent or waiting on an ACK)

There is more detail (and some great reference resources) on the question.

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