Dear all,
thank you very much for your quick replies. The solution:
alias @echo-on='set -x'
alias @echo-off='{ set +x; } 2>/dev/null'
PS4=
Solves the problem, and relieves from writing "echo COMMAND" before each
command that should be shown.
-Angelo Borsotti
On Wed, 12 Jun 2024 at 23:21, Koichi Murase <myoga.mur...@gmail.com> wrote:
> 2024年6月13日(木) 5:20 Angelo Borsotti <angelo.borso...@gmail.com>:
> > This is not the same as debugging, for which set -x is devoted.
> > "set -x" makes the ensuing commands be printed, but prefixed
> > with "+ ", which makes the result look ugly,
>
> PS4= (as Greg has replied)
>
> > not to mention that
> > the following "set +x" is echoed too (there are hacks to suppress
> > the "set +x" output, but they are just hacks).
>
> What are the hacks? What are the problems with them? You can have aliases:
>
> alias @echo-on='set -x'
> alias @echo-off='{ set +x; } 2>/dev/null'
>
> > I would stress the importance of this: the purpose of scripts is
> > to execute commands, informing the caller of what they execute,
> > purged of all the builtins and other calculations the script does
> > in order to come to the commands.
>
> I don't think the purpose of scripts is to execute only the external
> commands in general. The tasks implemented by builtins and other
> calculations are allowed to be the purpose of scripts.
>
> > Many solutions are posted in the internet, all of them are hacks with
> > lots of edge cases that make them fail in presence of commands
> > containing special characters, redirections, substitutions, etc.
>
> Have you tried `set -v'? `set -v' is not a hack, (though there doesn't
> seem to be a way to suppress echoing set +v).
>
> The detailed design of how the logged commands should be filtered and
> formatted depends on the purpose of each user. We already have `set
> -x' and `set -v'. We can adjust the format by PS4 for `set -x'. It's
> unrealistic to add a new option for every new preference of detailed
> filtering and formatting. If it is really needed, you can implement
> your filtering through the DEBUG trap, but it would finally be best to
> explicitly write `echo COMMAND' before every COMMAND that you think is
> important (unless you are lazy). It's stable and flexible.
>
> --
> Koichi
>
