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Re: PATCH: trailing components

On 6/18/19, Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx> wrote:
> Peter Stephenson wrote on Tue, 18 Jun 2019 13:01 +00:00:
>> I needed to preserve a number of trailing components of a path (other
>> than one) and couldn't think of an easy way of doing it.  Rather than
>> craft obscure pattern substitutions, or use an ad-hoc expression to
>> strip the prefix, I came up with a patch to add an optional number after
>> the "t" in history style modifiers to do this.  I put it after rather
>> than before because history-style colon expressions are quite sensitive
>> to what the first character is after the colon.
>> Before I come up with tests and fix up the ensuing failures, you can let
>> me know if there's a better way of doing this to save me the trouble.
> Here are some alternatives, but I'm not claiming any of them is better than
> «${foo:t2}»:
> f() {
>   REPLY=
>   for 1 in {1..$1} ; do REPLY=$2:t/$REPLY; 2=$2:h ; done
> }
> f $N "$foo"; foo=$REPLY
> or
> foo=${(j./.)${${(s./.)foo}[-$N,-1]}}
> (plus or minus handling of runs of several consecutive slashes)
> or
> tmp=$foo
> for i in {1..$N} ; do tmp=$tmp:h ; done
> foo=${foo#$tmp/*}

Here's one (two) more, excluding (including) empty segments in the count,
% a=a/b/c/d///e/g
% echo ${(M)a%%([^/]#(/|)##)(#c5)}
% echo ${(M)a%%([^/]#(/|))(#c5)}

Mikael Magnusson

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