Re: signal-handling problems for "dd": some thoughts

[Paul Jarc]

Jim Meyering <address@hidden> wrote:
> I suppose you're referring to this part of the POSIX spec:
>
>     The signals SIGUSR1 and SIGUSR2 are commonly used by applications for
>     notification of exceptional behavior and are described as ``reserved as
>     application-defined'' so that such use is not prohibited.

This sounds to me like an explicit approval of dd's use of SIGUSR1.

> And so dd shouldn't use SIGUSR1, because some application (e.g., a
> program that invokes dd) might use SIGUSR1 for something unrelated.

You mean a program might send SIGUSR1 to other, unrelated programs
(and therefore not knowing how they handle it)?  Sounds like a bug in
the killer.

> The ideal would be to find an approach that avoids adding a new option
> to each tool that supports a progress bar.

Environment variable?


paul