Re: vim: problem when searching and displaying certain lines with :global

On 15/06/12 06:15, ping wrote:
> still I'm thinking the exact syntax of this is kind of hard to
> understand...for my uneducated eyes at least...
>
> :g#classifier-group\>.*\n\s*[1-9]\d* packets, [1-9]\d* bytes#.,+1p
>
> //this means we are "extracting" the matched lines only, means what ever
> we'll do next based on this, we'll ignore those un-matched lines, it
> seems not the case...
> :g#classifier-group\>.*\n\s*[1-9]\d* packets, [1-9]\d* bytes#

the above means "every time there is a match for the pattern between the
#. If (as is more usual) it were shown between / it would be

/classifier-group\>.*\n\s*[1-9]\d* packets, [1-9]\d* bytes/

which would mean matching the following in sequence:

"classifier-group"
an end of word
any number of characters (as many as possible) on the same line
one line break
any number of spaces and/or tabs (as many as possible)
a character between 1 and 9 inclusive
any number of digits (as many as possible)
" packets, "
a character between 1 and 9 inclusive
any number of digits (as many as possible)
" bytes "

To replace "one line break" by "any number of lines, zero or more, as
few as possible" replace \n by \_$\_.\{-}\_^ which means

an end-of-line, also if not at the end of the pattern
any number of anything, including line breaks, as few as possible
a start-of-line, also if not at the start of the pattern

>
> //this is very tricky part for me
> .,+1p
>
> "." is "current line", for me this clearly should mean the "current
> matched line", which is actually 2 real lines here since we are running
> the multi-line regex.
> but obviously in this context, the "." was used to describe "only the
> 1st line out of all matched lines", right?

It means "every matched line". Since you got a multi-line pattern, it
means (IIUC) "the first line of every match".

>
> and that "+1":
> the "1st matched line" plus "1 more" line, but shouldn't that offset
> also be used from within the pool of matched lines? or regardless of
> match or not?

That offset is relative to the part before the comma, i.e. it means "the
line after the first line of every match".

> my test shows if you put +2 it will print non-matched lines too:

If you put +2 it will always print 3 lines starting at the first line of
every match.

>
> :g/classifier-group.*\n.*[1-9]\d* packets, [1-9]\d* bytes/.,+2p
> 41 classifier-group dhcp entry 1
> 42 313 packets, 118332 bytes
> 43 rate-limit-profile dhcplimit <--non-matched line
> 369 classifier-group jnpr-VIDEO-TRAFFIC entry 41
> 370 58658 packets, 8889186 bytes
> 371 rate-limit-profile video-upstream <--non-matched line
>
> so the right logic here looks is:
>
> :g/.../ find some matched line(S),
> no matter how many lines got matched, take only 1st line, trash all others
> use that as the start of the range
> use another offset (here +1) based on original text (not matched lines),
> as end of range
> print
>
>
> Then what if I want:
> the line containing classifier-group
> followed by a line x packets, y bytes
> followed by a line rate-limit-profile
> but I only want 1st & 3rd line under these constraint, since only these
> are interested lines?

that's harder: a :p command can print any number of *consecutive* lines.
But the :global command regards a | as part of its argument, so you
could have

:g/pattern/p|.+2p

to always print the (first) matching line and the second line after it.

See :help :Bar

Similarly, to print every line containing /pat1/ and (every time) the
first line containing /pat2/ after it, you could (IIUC) use

:g/pat1/p|/pat2/p

>
> (so following patterns will be ignored)
> classifier-group dhcp entry 1
> rate-limit-profile dhcplimit
> )
>
>
> regards
> ping

Oh, and BTW the preferred reply style in these groups is to put the
reply text below what you're replying to, and snip away irrelevant text
from older messages.


Best regards,
Tony.
--
The human animal differs from the lesser primates in his passion for
lists of "Ten Best".
-- H. Allen Smith

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