We normally do cat /proc/kmsg or dmesg to see the kernel logs from user space.
I understand the dmesg is a circular buffer which copies from kmsg. But is kmsg also not a circular buffer?
What is the difference and relation between them?
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Peter Mortensen
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Saurabh Sengar
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Have a look at [How to read ring buffer within linux kernel space?](http://stackoverflow.com/questions/9533708/how-to-read-ring-buffer-within-linux-kernel-space) for a great answer with nice references. – Mike Satteson Jan 30 '15 at 13:32
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Loosely speaking dmesg is a program that dumps /proc/kmsg. In addition, it provides some filtering capabilities to weed out logs that the user isn't interested in.
R.D.
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ye I know dmesg copies from /proc/kmsg. But as dmesg; is kmsg also a circular buffer ? – Saurabh Sengar Feb 02 '15 at 09:15
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2circular buffer is implemented by kernel itself, dmesg is just a util to read this circular via kernel interface /proc/kmsg – yuanjianpeng Oct 08 '19 at 01:58
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The output of /proc/kmsg can be directed to a file when collecting large amount of logs so that no logs are lost.
dmesg is circular buffer and previous logs get overwritten once the buffer is full.
Peter Mortensen
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Tarun Gupta
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