Re: Unknown vimrc line: %!awk

On Thu, Mar 19, 2015 at 3:44 AM, Christian Brabandt <cblists@256bit.org> wrote:

Am 2015-03-18 23:38, schrieb Christian Bone:

I haven't used Vim in a while and when I started using it again I
noticed this line in $MYVIMRC

:nnoremap <f3> :%!awk '!a[$0]{a[$0]=1;print}'<bar>noh<cr>

I understand that it's mapping to the F3 key, but I can't figure out
what the rest of the line does. Can anyone tell me?

This pipes your current buffer through awk with the awk oneliner:

'!a[$0]{a[$0]=1;print}'

Which I believe is a kind of uniq function.

E.g. each line will be output, if awk hasn't seen it before.

After that the vim command <bar>noh<cr> is executed. I am not
quite sure about that one, I suspect it is trying to use :noh
(e.g. disable search highlighting using the :noh command), but
I wonder why the ':' is missing.

Best,
Christian

     I think there are two problems.

     First, the second "!" gets replaced by the previous external command.  I think you want to escape it:  '\!a[$0]{...}'.

     Second, when the :nnoremap command is executed, the <bar> becomes a "|" character (pipe) and the <cr> becomes an end-of-line character ... but the latter is the only thing terminating the :!, meaning that the "|" is part of the external command.  So, after applying the awk filter, you apply the noh filter.  I don't know about you, but I have never heard of noh.

     To get something that does not generate errors, I would try this:

nnoremap <F3> :%!awk '\!a[$0]{a[$0]=1;print}'<cr>:noh<cr>

I do not know if that matches the original intent.  The awk command does seem to do what Christian described.

:help :!

:help 'cpoptions' 

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