Re: Checking executability for asynchronous commands

[Andreas Kusalananda Kähäri]

On Fri, Dec 25, 2020 at 10:40:17AM +0100, Markus Elfring wrote:
> Hello,
> 
> I am looking for another bit of clarification according to an implementation 
> detail.
> 
> The manual is providing the following information.
> https://git.savannah.gnu.org/cgit/bash.git/tree/doc/bash.1?id=76404c85d492c001f59f2644074333ffb7608532#n627
> 
> “…
>        If  a command is terminated by the control operator &, the shell 
> executes the command in the background in a subshell.  The shell does not 
> wait for the command to finish, and the
>        return status is 0.
> …”
> 
> 
> Thus I observe a behaviour like the following for a simple test with the
> software “bash 5.0.18-3.1” according to a “program” which does not exist here.
> 
> elfring@Sonne:~> xy &
> [1] 4063
> xy: Befehl nicht gefunden
> [1]+  Exit 127                xy
> 
> 
> I imagine that it can be occasionally helpful to determine the execution 
> failure
> in the synchronous way.
> Would it make sense to configure the error reporting for selected asynchronous
> commands so that they would become background processes only after the 
> required
> check for executability?

How would you propose that the shell handle something like the following?

        ( cmd1 && cmd2 ) &

Are you maybe saying 

        cmd &

should be a special case?

-- 
Andreas (Kusalananda) Kähäri
SciLifeLab, NBIS, ICM
Uppsala University, Sweden

.