On Fri, Aug 26, 2022 at 08:17:10AM +0100, Tim Woodall wrote:
> $ cat Makefile.test
> SHELL := /bin/bash -u
> MAKEFLAGS += --no-builtin-rules
> .SUFFIXES:
>
> all:
> echo done
> $ make -f Makefile.test
> echo done
> done
> $ make -f Makefile.test | cat
> echo done
> /etc/bash.bashrc: line 7: PS1: unbound variable
^^^^^^^^^^^
[...]
> Why do I get that unbound variable error? (I know how to fix it, I just
> don't understand why it only happens when I pipe the output)
If I were you, I'd go looking at your /etc/bashrc and see what's around
line 7. Mine says (line numbers added by me):
6 # If not running interactively, don't do anything
7 [ -z "$PS1" ] && return
...and indeed, bash -u complains there, because it tries to expand an
(unset) PS1 before checking it for emptyness.
> And is this a bug? In make?
Arguably it's a bug(let) in /etc/bash.bashrc. This would work better:
[ -z "${PS1:-}" ] && return
But I'll defer to more shell-savvy people for a proper fix.
> The only way I've managed to reproduce this other than as above is by
> explictly sourcing /etc/bash.bashrc where there are a few places where
> set -u can report unbound variables.
I think this /is/ what you are seeing.
Cheers
--
t
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