Paramater subsiution

Paramater subsiution

[Lewis Butler]

Given:

name="file 1234 - name"
echo ${I% - name}

I can easily get 'file', but how would I get "name" instead given that:

	o name and 1234 are variable lengths and values 
	o "file" and " - " are constant across all the input


I've trued using 

${i:s/file \[0-9\]+ - //}
${i:s/file \[0-9\]\[0-9\]\[0-9\]\[0-9\] - //}
${i:s/file [0-9]+ - //}
${i:s/file [0-9][0-9][0-9][0-9] - //}
${i:s/file [^ ]+ - //}

And similar to no avail, though:

${i:s/file //} 

prints "1234 - name"


-- 
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<mailto:lbutler@covisp.net>
tel:+1.303.219.0564

Re: Paramater subsiution

[Gamma]

Jun 27, 2021 17:42:48 Lewis Butler <lbutler@covisp.net>:

> Given:
>
> name="file 1234 - name"
> echo ${I% - name}
>
> I can easily get 'file', but how would I get "name" instead given that:
>
>   o name and 1234 are variable lengths and values
>   o "file" and " - " are constant across all the input

echo ${i##* - }

Removes the longest prefix ending with ' - '.

Check man zshexpn for more.

Re: Paramater subsiution

[Lawrence Velázquez]

On Sun, Jun 27, 2021, at 6:47 PM, Gamma wrote:
> echo ${i##* - }
> 
> Removes the longest prefix ending with ' - '.

${i#* - } would also work and would permit "name" to be completely
arbitrary (assuming that "file 1234" could not possibly contain
" - " as a substring).

https://zsh.sourceforge.io/Doc/Release/Expansion.html#Parameter-Expansion

On Sun, Jun 27, 2021, at 6:40 PM, Lewis Butler wrote:
> I've trued using
> 
> ${i:s/file \[0-9\]+ - //}
> ${i:s/file \[0-9\]\[0-9\]\[0-9\]\[0-9\] - //}
> ${i:s/file [0-9]+ - //}
> ${i:s/file [0-9][0-9][0-9][0-9] - //}
> ${i:s/file [^ ]+ - //}

First, you probably wanted ${i/foo/bar} rather than ${i:s/foo/bar}.
The latter matches foo literally unless the HIST_SUBST_PATTERN
option is set.  It's also less appropriate in a conceptual sense.

Second, these substitution features use patterns ("globs"), not
regular expressions.  Bracket expressions are treated specially
([...], not \[...\]), but '+' generally is not.  You can find details
here, including how you could achieve the same effect as '+' (if
you really must):

https://zsh.sourceforge.io/Doc/Release/Expansion.html#Filename-Generation

But you should use Gamma's solution (or my variant), which is simple
and highly portable.

-- 
vq

Re: Paramater subsiution

[Lewis Butler]

On 27 Jun 2021, at 16:47, Gamma <GammaFunction@vivaldi.net> wrote:
> Jun 27, 2021 17:42:48 Lewis Butler <lbutler@covisp.net>:
> 
>> Given:
>> 
>> name="file 1234 - name"
>> echo ${I% - name}
>> 
>> I can easily get 'file', but how would I get "name" instead given that:
>> 
>>   o name and 1234 are variable lengths and values
>>   o "file" and " - " are constant across all the input
> 
> echo ${i##* - }

<thunks head on desk>

> Removes the longest prefix ending with ' - '.
> 
> Check man zshexpn for more.

I swear I knew that at one point, but missed it several times in reading the man page.

Thank you.

-- 
ɹןʇnqן
<mailto:lbutler@covisp.net>
tel:+1.303.219.0564