Re: 5.1 regression?

[Greg Wooledge]

On Mon, Aug 01, 2022 at 04:37:18PM +0900, Dominique Martinet wrote:
> Harald Dunkel wrote on Mon, Aug 01, 2022 at 09:08:40AM +0200:
> > a colleague pointed me to a changed behavior of bash 5.1.4 in Debian 11.
> > ----
> > #! /bin/bash
> > # set -x
> > 
> > insert()
> > {
> >    local data="$1"
> >    local lineNumber="$2"
> > 
> >    head -n "$lineNumber"
> 
> The problem is that stdin is eaten up by this head command.
> 
> What changed is that bash used to store stdin input in a temporary file,
> so head could seek back to the actual position in the stream after the
> first three lines but that no longer works:

Specifically, this part of the bash 5.1 changelog:

c. Here documents and here strings now use pipes for the expanded document if
   it's smaller than the pipe buffer size, reverting to temporary files if it's
   larger.