Re: backreferences

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Oct 15, 11:28am, Ray Andrews wrote:
} Subject: backreferences
}
}     sstring="before inside after"
}     if [[ "$sstring" = (#b)([^i]#inside)(*) ]];
} 
} ... all good.  But is is possible to populate 'match'
} without the 'if' test?

The [[ ]] syntax is not part of the "if" syntax; "if" is followed by
a command whose exit status is tested, so [[ ]] is a command.  Thus
you can simply write

    [[ "$sstring" = (#b)([^i]#inside)(*) ]]

by itself.  You do need the [[ ]] context to invoke pattern matching.

} Better question:
} 
} In this construction " [^i] " is it possible to use a
} string rather than a character in the exclusion test?

I'm not sure what you're asking.  In a pattern, [string] is a character
class (match any of s,t,r,i,n,g) and [^string] is the inverse of that
character class, but that whole subexpression always matches only one
character in the tested string.

So "use a string rather than a character" might mean that you want to
construct a character class by writing something similar to [^$class] 
where the parameter $class needs to be expanded, or it might mean that
you're trying to not-match multiple characters in the tested string in
a certain order.  In the latter case you want ^(string), or more often
(^(string)), but you also must setopt EXTENDED_GLOB.