Re: subsitutions and beginning of lines.

[Ray Andrews <rayandrews@eastlink.ca>]

On 10/11/2015 01:09 PM, Peter Stephenson wrote:
> On Sun, 11 Oct 2015 12:12:26 -0700
> Ray Andrews <rayandrews@eastlink.ca> wrote:
>> ${var// /}
>>
>> When doing that sort of substitution, is is possible to test for newlines?
>> I'm playing with a function that grabs history and I'm trying to strip
>> off the leading numbers.  At one point I have the output captured in a
>> variable and various forms of substitution come close, but the substitution
>> treats the entire variable as one entity whereas I want the substitution
>> to be performed fresh on each new line of output.  I can't find any
>> specific newline character.  OTOH if the variable was an array there'd
>> probably be some way of processing each line as a separate entity, which
>> would serve fine. I know I'm close, but I can't quite bag it.
> If I'm following, you are indeed nearly there: you need to split the
> variable to an array on newlines, while not splitting on anything else.
> To do that, you quote the array, then force the splitting which ensures it
> only gets split on what you tell it and not other other random spaces:
>
> var="1:one two
> 2:three four"
> print -l -- ${(f)"${var}"}
>
> The -l prints one element per line for clarity.
>
> You've now got the lines you want as if they were array elements.  You
> can then surround that substitution with the sort you first thought of.
> For example, to strip the "number:",
>
> print -l -- ${${(f)"${var}"}##<->:}
>
> where, as you now know, <-> matches any set of digits.
>
> pws
Thanks Peter,  I just came up with this:

     echo "${(F)var[@]//#???????/}"

... it seems the numeric leader is always the same width, so mine is 
more stupidly
linear, but it was my enlightenment as to '<->' that got me going with this.
I pretty much understand it; the trick was to get the substitution on 
each element.
And get the newline as the separator.  I'll study your version too.

BTW, I just rediscovered your:

A User's Guide to the Z-Shell
Peter Stephenson
2003/03/23

In the fog of war I'd considered it to be 'the manual' back when I first 
started,
then when I started reading the real manual I had this powerful 
sensation that
the manual had gone downhill.  Now I'm realizing that they're not the same
tome after all and I must say that yours is a pleasure to read which 
can't be
said of the manual.  Is there an update?