Re: Weird set -u error

[Tim Woodall <debianuser@woodall.me.uk>]

On Fri, 26 Aug 2022, Tim Woodall wrote:

> $ cat Makefile.test
...
>

Many thanks everybody for all of the help understanding this.

Not this exact issue but effectively the same was reported in bug
#944780 and the unbound variable in /etc/bash.bashrc was reported in
#941248

I've now submitted a patch to #944780 that I think fixes all of the
cases where this fails, viz

bash -c 'echo $SHLVL' &
( bash -c 'echo $SHLVL' )
$( bash -c 'echo $SHLVL' )
bash -c 'echo $SHLVL' | cat
coproc bash -c 'echo $SHLVL'

All of which incorrectly (IMO) fail to increment SHLVL

I found this amusing case where I can decrement SHLVL below 1. I haven't
managed to get it to go negative.

$ echo $SHLVL
1
$ cat Makefile.test
all:
        echo $$SHLVL
$ make -f Makefile.test | cat
echo $SHLVL
0
$

Tim.