On 3/2/21 8:20 AM, Tom Rini wrote:
On Mon, Mar 01, 2021 at 06:07:36PM -0500, Sean Anderson wrote:
On 3/1/21 1:26 PM, Heinrich Schuchardt wrote:
On 3/1/21 3:17 PM, Tom Rini wrote:
On Sun, Feb 28, 2021 at 06:51:53PM -0500, Sean Anderson wrote:
On 2/28/21 6:40 PM, Heinrich Schuchardt wrote:
Am 28. Februar 2021 22:29:51 MEZ schrieb Sean Anderson <sean...@gmail.com>:
If there were no variable substitutions in a command, then initial
assignments would be misinterpreted as commands, instead of being
skipped
over. This is demonstrated by the following example:
=> foo=bar echo baz
The commit message does not explain why this patch is needed.
This is a bug I noticed while writing some tests of hush.
What shall be the value off foo after this line?
It should be bar. This is an existing difference when compared with
bash. For example, without this patch, we have
=> foo=bar echo $foo
bar
=> echo $foo
bar
This seems really awkward. In bash I get:
$ foo=bar ./test.sh
bar
$ echo $foo
$
Where test.sh
#!/bin/sh
echo $foo
I did not expect an assignment made before a command to stick.
Yeah, this is because hush does not have the concept of per-command
assignments (scope). So everything happens in the global scope.
What will be the output of
foo=bar echo ${foo}
with and without your patch?
It is the same.
Please, provide an example where the patch makes a difference.
Best regards
Heinrich
bash works as you describe. dash and busybox-sh both function like
this:
$ foo=bar echo $foo
$ echo $foo
$
That we error out entirely is different from everyone. Is that a good
thing? Maybe. I know I've caught myself making thinkos due to that
logic. It does also violate the principal of least surprise, that we
don't act like anything else. But I would suggest the behavior of
busybox-sh (what we forked long long ago) is what we should model here
rather than be more bash-like. I'm not all that firm on this opinion
frankly, especially given the one-line nature of the change to bring us
that behavior and I assume dash/busybox are acting like pure sh would in
this case, which we aren't anyhow.
Ok, I'd like to clear things up. Here is the current behavior of U-Boot:
=> foo=bar echo $foo
bar
=> echo $foo
bar
=> baz=bar echo qux
Unknown command 'baz=bar' - try 'help'
I see this as well (which isn't what I said in another part of this
thread, so I re-checked just now).
with this patch, this changes to
=> foo=bar echo $foo
bar
=> echo $foo
bar
=> baz=bar echo qux
qux
This patch *only* affects cases where there is an assignment at the
beginning of the line, but there is *no* variable reference in the
command. I know this is an edge case, but the current logic is clearly
wrong here.
OK. But I don't see that behavior in bash 4.4.20 (Ubuntu 18.04). Where
does one get a shell that works like you're changing our hush to?
I'm not changing hush to work like the first two examples, it's already like
this.
Only the third example is affected by this patch.
--Sean
