Zsh Mailing List Archive
Messages sorted by: Reverse Date, Date, Thread, Author

Re: subsitutions and beginning of lines.

On 10/11/2015 01:09 PM, Peter Stephenson wrote:

On Sun, 11 Oct 2015 12:12:26 -0700
Ray Andrews <rayandrews@xxxxxxxxxxx> 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?
Messages sorted by: Reverse Date, Date, Thread, Author