Extracting Informations from strings

Extracting Informations from strings

[Stefan Reichör]

Hi!

I want to parse the output from acpi:
  Battery 1: charging, 95%, charging at zero rate - will never fully charge.

I want to extract the "95%" from the output above.

How can I achieve this from within zsh?


Stefan.

Re: [zsh] Extracting Informations from strings

[Artur Penttinen]

On Mon, 21 Jun 2004, Stefan [iso-8859-1] ReichЖr wrote:

> Date: Mon, 21 Jun 2004 09:02:44 +0200
> From: "Stefan [iso-8859-1] ReichЖr" <xsteve@riic.at>
> To: zsh-users@sunsite.dk
> Subject: [zsh] Extracting Informations from strings
>
> Hi!
>
> I want to parse the output from acpi:
>   Battery 1: charging, 95%, charging at zero rate - will never fully charge.
>
> I want to extract the "95%" from the output above.
>
> How can I achieve this from within zsh?

  # print "Battery 1: charging, 95%, charging at zero rate - will never fully charge." |  cut -d, -f2
   95%
  #

-- 
artur penttinen

Re: [zsh] Extracting Informations from strings

[Vincent Stemen]

On Mon, Jun 21, 2004 at 10:24:16AM +0300, Artur Penttinen wrote:
> On Mon, 21 Jun 2004, Stefan [iso-8859-1] Reich?r wrote:
> 
> > Date: Mon, 21 Jun 2004 09:02:44 +0200
> > From: "Stefan [iso-8859-1] Reich?r" <xsteve@riic.at>
> > To: zsh-users@sunsite.dk
> > Subject: [zsh] Extracting Informations from strings
> >
> > Hi!
> >
> > I want to parse the output from acpi:
> >   Battery 1: charging, 95%, charging at zero rate - will never fully charge.
> >
> > I want to extract the "95%" from the output above.
> >
> > How can I achieve this from within zsh?
> 
>   # print "Battery 1: charging, 95%, charging at zero rate - will never fully charge." |  cut -d, -f2
>    95%
>   #
> 
> -- 
> artur penttinen

You can also do this directly without calling cut.

output="Battery 1: charging, 95%, charging at zero rate - will never fully charge."

output=${${=output}[4]}     # Split $output and extract the 4th field
print ${output%,}           # Remove the comma

-- 
Vincent Stemen
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Read how Network Solutions (NSI) was involved in stealing our domain name.
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Re: Extracting Informations from strings

[Peter Stephenson]

Stefan =?iso-8859-1?Q?Reich=F6r?= wrote:
> Hi!
> 
> I want to parse the output from acpi:
>   Battery 1: charging, 95%, charging at zero rate - will never fully charge.
> 
> I want to extract the "95%" from the output above.
> 
> How can I achieve this from within zsh?

Within zsh, you need something like (assuming the output is in $string):

setopt extendedglob
local match mbegin mend
if [[ $string = (#b)"Battery "*" charging, "(<->)"%"* ]]; then
  print "Charge is ${match[1]}%"
fi

It's up to you how closely you want to match the output, I've matched a
lot of it with *'s.

This works from zsh 4.0.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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Re: Extracting Informations from strings

[Bart Schaefer]

On Mon, 21 Jun 2004, Peter Stephenson wrote:

> Stefan =?iso-8859-1?Q?Reich=F6r?= wrote:
> >   Battery 1: charging, 95%, charging at zero rate - will never fully charge.
> > 
> > I want to extract the "95%" from the output above.
> 
> setopt extendedglob
> local match mbegin mend
> if [[ $string = (#b)"Battery "*" charging, "(<->)"%"* ]]; then
>   print "Charge is ${match[1]}%"
> fi

To do this without extendedglob and backreferences is, I think, simpler:

	print Charge is ${(M)${(M)string%%<->%,*}##<->%}

This is (where <-> matches a string of digits):

	${(M)string%%<->%,*}	Longest suffix beginning with <->%
	${(M)...##<->%}		Longest prefix of that matching <->%

I'd only resort to backreferences when the substring to be extracted is
ambiguous (e.g. "... charging, 95%, charging at 17%, ...") or when
extracting multiple fields (e.g. both the battery number and the charge
percentage).