Re: Wanted: bash enhancement... non-blocking 'wait'

[Philip Prindeville]

 On 9/3/10 10:44 AM, Eric Blake wrote:
> On 09/02/2010 04:44 PM, Philip Prindeville wrote:
> > I wanted to check in and see if there was a chance of this feature being
> > accepted upstream before I spent any time on it... so here goes.
> >
> > The "wait [n]" command is handy, but would be even handier is:
> >
> > wait [[-a] n]
> >
> > instead, which asynchronously checks to see if process 'n' has completed.
>
> What's wrong with using the existing 'kill -0 pid' to check if pid still 
> exists, rather than inventing a new argument to 'wait'?

Well, in theory, if you waited long enough (to look for the process), and it 
had exited and a new process with that id was created, you'd detect the wrong 
process.

At least with 'wait' you're guaranteed it's still in your process-group, right?

Besides, 'wait' is just a lot easier to read and understand... not everyone 
knows the system call semantics of kill().