Re: alternation option end of string

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

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.