Re: [PATCH 2/2] selftests: livepatch: functions.sh: Workaround heredoc on older bash

[Marcos Paulo de Souza]

On Thu, 2026-02-26 at 11:34 -0300, Marcos Paulo de Souza wrote:
> On Thu, 2026-02-26 at 13:40 +0100, Miroslav Benes wrote:
> > Hi,
> > 
> > On Mon, 23 Feb 2026, Marcos Paulo de Souza wrote:
> > 
> > > On Mon, 2026-02-23 at 10:42 -0500, Joe Lawrence wrote:
> > > > On Fri, Feb 20, 2026 at 11:12:34AM -0300, Marcos Paulo de Souza
> > > > wrote:
> > > > > When running current selftests on older distributions like
> > > > > SLE12-
> > > > > SP5 that
> > > > > contains an older bash trips over heredoc. Convert it to
> > > > > plain
> > > > > echo
> > > > > calls, which ends up with the same result.
> > > > > 
> > > > 
> > > > Acked-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> > > 
> > > Thanks for the review Joe!
> > > 
> > > > 
> > > > Just curious, what's the bash/heredoc issue?  All I could find
> > > > via
> > > > google search was perhaps something to do with the temporary
> > > > file
> > > > implementation under the hood.
> > > 
> > > # ./test-ftrace.sh 
> > > cat: -: No such file or directory
> > > TEST: livepatch interaction with ftrace_enabled sysctl ...
> > > ^CQEMU:
> > > Terminated
> > 
> > I cannot reproduce it locally on SLE12-SP5. The patched test-
> > ftrace.sh 
> > runs smoothly without 2/2.
> > 
> > linux:~/linux/tools/testing/selftests/livepatch # ./test-ftrace.sh 
> > TEST: livepatch interaction with ftrace_enabled sysctl ... ok
> > TEST: trace livepatched function and check that the live patch
> > remains in effect ... ok
> > TEST: livepatch a traced function and check that the live patch
> > remains in effect ... ok
> > 
> > GNU bash, version 4.3.48(1)-release (x86_64-suse-linux-gnu)
> > 
> > Does "set -x" in the script give you anything interesting?
> 
> Nope:
> 
> boot_livepatch:/mnt/tools/testing/selftests/livepatch # ./test-
> trace.sh
> + cat     
> cat: -: No such file or directory            
> + set_ftrace_enabled 1                                     
> + local can_fail=0
> 
> 
> Same version here:
> GNU bash, version 4.3.48(1)-release (x86_64-suse-linux-gnu)
> 
> I'm using virtme-ng, so I'm not sure if this is related. At the same
> time it works on SLE15-SP4, using the same virtme-ng, but with a
> different bash:
> GNU bash, version 4.4.23(1)-release (x86_64-suse-linux-gnu)
> 
> So I was blaming bash for this issue...

This patch can be skipped. For the record, I discovered that it only
happens when vng is called using --rw, making it to fail on older bash
since it doesn't create overlays for /tmp. If the overlay is added the
issue is gone.

So, this patch can be skipped. Thanks Miroslav for testing!

> 
> > 
> > Miroslav