Cross-version regular expression...

[Ray Van Dolson]

I'm trying to get regular expression matching working on both bash v3
as well as v4.

The following works on v4 (under RHEL6), but not under bash 3.00.15
(under RHEL4):

[[ "6Server" =~ ([0-9]+)(.*) ]]

This works on 3.00.15, but not under RHEL6's bash (4.1.2):

[[ "6Server" =~ '([0-9]+)(.*)' ]]

The prior actually throws a syntax error, so I can't even code around
the syntax based on evaluation of $BASH_VERSINFO.

Any thoughts on how to do this in a portable way?

Thanks,
Ray

Re: Cross-version regular expression...

[Ray Van Dolson]

On Wed, Apr 13, 2011 at 12:28:39PM -0700, Greg Wooledge wrote:
> On Wed, Apr 13, 2011 at 11:19:22AM -0700, Ray Van Dolson wrote:
> > I'm trying to get regular expression matching working on both bash v3
> > as well as v4.
> 
> Put the RE in a variable.
> 
> > The following works on v4 (under RHEL6), but not under bash 3.00.15
> > (under RHEL4):
> > 
> > [[ "6Server" =~ ([0-9]+)(.*) ]]
> 
> Put the RE in a variable.
> 
> > This works on 3.00.15, but not under RHEL6's bash (4.1.2):
> > 
> > [[ "6Server" =~ '([0-9]+)(.*)' ]]
> 
> Put the RE in a variable.  Don't quote the right hand side.  If you quote
> the right hand side, it becomes == matching instead of =~ matching.
> 
> re='([0-9]+)(.*)'
> [[ 6Server =~ $re ]]
> 

Thanks Greg!