[j-nsp] why is "show log messages | last 10" so slow?

[Hugo Slabbert]

On Mon 2018-Oct-29 16:28:12 +0000, Anderson, Charles R <cra at wpi.edu> wrote:

>Why is "show log messages | last 10" so slow with a large log file when I 
>can go to the shell and run "tail -10 /var/log/messages" much more 
>quickly?

Because it's an action that is done after the pipe rather than being the 
action itself, so it's equivalent to `cat /var/log/messages | tail -n 10` 
not directly to `tail -n 10 /var/log/messages`.  It's a generic pipe action 
that can be applied to any text output, e.g. the output of a regular 
operational "show" command, but it's not a top-level command that does file 
processing itself like `tail` can.

>Maybe JUNOS can borrow the implementation of the "tail" command to make it 
>quicker.

They'd have to add a new top-level command or perhaps add a parameter to 
the `file show` operation, I'd think.  Probably doable, but not sure how 
much traction the feature request would get.

-- 
Hugo Slabbert       | email, xmpp/jabber: hugo at slabnet.com
pgp key: B178313E   | also on Signal
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