[OE-core] [PATCH] terminal.bbclass: use var-SHELL as the shebang of wrapper script

[Hongxu Jia]

On 2018年09月05日 10:41, Andre McCurdy wrote:
> On Tue, Sep 4, 2018 at 7:16 PM, Hongxu Jia <hongxu.jia at windriver.com> wrote:
>> On 2018年09月05日 09:59, Andre McCurdy wrote:
>>> On Tue, Sep 4, 2018 at 6:02 PM, Hongxu Jia <hongxu.jia at windriver.com>
>>> wrote:
>>>> On 2018年09月05日 03:14, Andre McCurdy wrote:
>>>>> Maybe I'm missing something, but what's the advantage of using SHELL
>>>>> to run this little wrapper script rather than hardcoding /bin/sh ?
>>>>>
>>>>> Task shell scripts created by bitbake use hardcoded /bin/sh (see
>>>>> bitbake/lib/bb/build.py -> shell_trap_code())
>>>> Keep align with the devshell as the comments mentioned above
>>> Yeah, I've read the comments. I still don't really understand why.
>>>
>>>> The devshell.bbclass set var-SHELL to var-DEVSHELL, and terminal.bbclass
>>>> initial var-SHELL with `bash'. Keep sync with it, use var-SHELL rather
>>>> than hardcoded `/bin/sh' as the shebang of wrapper script.
>>>>
>>>> On Ubuntu host, default shell is dash (/bin/sh -> dash), even though
>>>> we assign var-SHELL with `/bin/bash', the wrapper script is still
>>>> dashism.
>>> What exactly is a dashism?
>>
>> In another word, it does not support bashism.
>>
>> Here is a case which `export -f' is bashism although
>>
>> devshell using bash, but /bin/sh -> dash
>>
>> [case]
>>
>> function foobar { echo foobar; };
>>   export -f foobar
>> bitbake -c devshell virtual/kernel
>>
>> [case]
>>
>>
>> BTW, I've sent anther patch to fix it `[OE-core] [PATCH]
>> devshell.bbclass/terminal.bbclass: add a shell check at devshell'
> OK, but run.do_terminal.xxx is a trivial wrapper which (apart from
> exporting environment variables) just contains something like:
>
>    do_terminal() {
>    exec pseudo /bin/bash
>    }
>
>    do_terminal
>
> I'm not sure what the problem is running that with /bin/sh, regardless
> of whether /bin/sh points to bash or dash?

Isn't clear? In above case, even though `exec pseudo /bin/bash',

since /bin/sh points to dash, the devshell started failed

[snip]

bitbake -c devshell virtual/kernel
Trying to run: screen -r devshell_23640
Cannot open your terminal '/dev/pts/39' - please check.

[snip]

Since `export -f' is bashism, use dash to load wrapper script failed


//Hongxu