Re: [PATCH] core.5: explain the new situation with argument splitting

Re: [PATCH] core.5: explain the new situation with argument splitting

[Michael Kerrisk (man-pages)]

Hello Paul,

On 8/7/19 3:45 AM, Paul Wise wrote:
> It changed in Linux v5.3-rc3 commit 315c69261dd3 from
> splitting after template expansion to splitting beforehand.

Thanks. Patch applied.

Cheers,

Michael

> ---
>  man5/core.5 | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/man5/core.5 b/man5/core.5
> index d3efca3f8..ddc0352b8 100644
> --- a/man5/core.5
> +++ b/man5/core.5
> @@ -267,6 +267,20 @@ file.
>  If the first character of this file is a pipe symbol (\fB|\fP),
>  then the remainder of the line is interpreted as the command-line for
>  a user-space program (or script) that is to be executed.
> +.PP
> +.\" 315c69261dd3fa12dbc830d4fa00d1fad98d3b03
> +Since kernel 5.3.0, the pipe template is split on spaces into an
> +argument list before the template parameters are expanded.
> +In earlier kernels the template parameters are expanded first and
> +the resulting string is split on spaces into an argument list.
> +This means that in earlier kernels executable names added by the
> +%e and %E template parameters could get split into multiple arguments.
> +So the core dump handler needs to put the executable names as the last
> +argument and ensure it joins all parts of the executable name using spaces.
> +Executable names with multiple spaces in them are not correctly represented
> +in earlier kernels so the core dump handler needs to use mechanisms to find
> +the executable name.
> +.PP
>  Instead of being written to a disk file, the core dump is given as
>  standard input to the program.
>  Note the following points:
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/