Re: waiting for process substitutions

[Chet Ramey]

On 6/29/24 8:47 AM, Zachary Santer wrote:
>  From the manual:
> wait [-fn] [-p varname] [id ...]
> Wait for each specified child process and return its termination
> status. Each id may be a process ID or a job specification; if a job
> spec is given, all processes in that job's pipeline are waited for. If
> id is not given, wait waits for all running background jobs and the
> last-executed process substitution, if its process id is the same as
> $!, and the return status is zero. [...]
>
> Why do this? 

Because it sets $!. You should always be able to wait for $!. Originally
there was no way to wait for a process substitution at all.

Why not just wait for all process substitutions?

Process substitutions are word expansions, with a scope of a single
command, and are not expected to survive their read/write file descriptors
becoming invalid. You shouldn't need to `wait' for them; they're not
true asynchronous processes.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

OpenPGP_signature.asc
Description: OpenPGP digital signature