Re: Bug report: extended pattern match bug (or "feature" [sic] /inconsistency)

[linda W]

Chet Ramey wrote:

> > I have a file in a directory:
> >
> >    3ddiag-0.703-176.i586.rpm
> >
> > I am attempting to set a variable to the name of this file while not
> > matching other varients of the name.
> >
> > I decided to use the pattern (correct or not):
> >
> >    $a-+([-0-9.a-z])$b)
> >
> > "a" and "b" are set:
> >
> >    a=3ddiag
> >    b=i586.rpm
> >
> > So to set a variable "cur" (indicating current version in current 
> > directory), I used:
> >
> >    cur=$a-+([-0-9.a-z])$b
> >
> > However, in the above context, the regular expression for the path is 
> > not evaluated.
> > What I get is:
> >
> >    echo "$cur"
> >    
>
> Make sure you have the `extglob' option set
---
   If I did not have the "extglob" option set, then the 2nd expansion 
cur=$(echo $a-+([-0-9.a-z])$b) wouldn't
have worked (i.e. it is set).

> and unquote the expansion.
>  
The expansion is unquoted:

cur=$a-+([-0-9.a-z])$b


> Quotes inhibit pathname expansion.
>  
	I know, but to see the "real" value inside "$cur", I have to use quotes, 
otherwise, I get a 2nd expansion when I use "echo" to print out the value of $cur.
That wouldn't show the contents of cur but would show the contents after having 
been
_re_-evaluated_.  The problem I'm trying to show is that the value stored in 
"cur" is
not expanded if I use "straight assignment", but is evaluated if I pre-evaluate it as the 
output of a subprocess.  But a subprocess isn't required to evaluate the expression, since 
typing the express "naked" (not in an assignment), does evalute it correctly the first time:

> a=3ddiag
> b=i586.rpm
> echo $a-+([-0-9.a-z])$b
3ddiag-0.703-176.i586.rpm                       ## expanded correctly on first 
try

I'll show you a different example that uses no quotes but still shows the 
difference:

> export cur=$a-+([-0-9.a-z])$b
> printenv|grep cur            
cur=3ddiag-+([-0-9.a-z])i586.rpm                ## value in cur is stored in 
unexpanded form
> export cur=$(echo $a-+([-0-9.a-z])$b)
> printenv|grep cur                    
cur=3ddiag-0.703-176.i586.rpm                   ## value in cur is stored in 
expanded form


---
sorry for curtness email, gotta run/ late4 appt.
-linda