Re: alternation option end of string

On 2026-05-02 02:47, Roman Perepelitsa wrote:
> This should do it, if I understood your requirements correctly:
>
> ${${(M)string:#cat(|s*)}[1,4]}
But the length of the string is arbitrary I can't use any sort of length.
>
> Another option would be to capture the interesting part of the match 
> explicitly (requires extended_glob):
>
> [[ $string == (#b)((cat)|(cats)*) ]] && out=$match[2]$match[3] || out=
That tests fine.  Too bad what Mark said about using the '$' to test for 
the end of the string seems not to work, it would have been simpler.  In 
my actual situation I'm testing for a comma then a number, and only a 
number,  either at the end of the string OR followed by another comma 
and then anything or nothing else:

     [[ $remainder == (#b)(,(<->)|,(<->),*) ]] && s_idx=$match[2]$match[3]

In practice I'm breaking filenames into a base, an index and any 
following comment, it's part of my backup system.  It's been 99% perfect 
for a long time, but there's always another gotcha and one showed up a 
few days ago and it's an exercise to get it bloody perfect, which I did, 
but it was a bit convoluted.  Your way is much better.  Here's some 
tortures:

INPUT: file
base:       file
idx:
comment:

INPUT: file,
base:       file
idx:
comment:

INPUT: file,8
base:       file
idx:        8
comment:

INPUT: file,88
base:       file
idx:        88
comment:

INPUT: file,8,comment
base:       file
idx:        8
comment:    comment

INPUT: file,88,comment
base:       file
idx:        88
comment:    comment

INPUT: file,8a
base:       file
idx:
comment:    8a

INPUT: file,a8
base:       file
idx:
comment:    a8

INPUT: file,a8,comment
base:       file
idx:
comment:    a8,comment

INPUT: file,8a,comment
base:       file
idx:
comment:    8a,comment

INPUT: file,8a,com,ment
base:       file
idx:
comment:    8a,com,ment

INPUT: file,8,com,ment
base:       file
idx:        8
comment:    com,ment

INPUT: file,8,comm,9
base:       file
idx:        8
comment:    comm,9

INPUT: file,8,comm,9a
base:       file
idx:        8
comment:    comm,9a

INPUT: file,8,comm,a9
base:       file
idx:        8
comment:    comm,a9

... but there's probably still some lurking gotcha that might sneak 
thru. Hard to think up every possible torture.