Allow timeout for Exec to avoid hanging

[rcowham]

It would be nice to be able to specify a timeout to avoid commands hanging during execution.

Maybe something like the existing WithEnv(), but instead WithTimeout() or WithWaitDelay() to support the new (Go 1.20) WaitDelay?

https://pkg.go.dev/os/exec#Cmd.WaitDelay

[bitfield]

Great suggestions, @rcowham! There's been some previous discussion on this, if you haven't already seen it: in #207 and #105, for example. Would you like to review those and see if you can propose a concrete example program to demonstrate your idea?

Good feature proposals tend to satisfy as many as possible of the following criteria:

1. Show that the lack of such a feature is a significant problem for a significant number of users
2. Propose a feature that addresses the problem in a satisfactory way
3. Include a runnable example program that shows how the proposed syntax or API would be used to solve the problem for a realistic use case
4. Show that this is significantly better than any exisitng solution without the feature

[rcowham]

For my use cases, a timeout on the whole pipeline is sufficient - just want to avoid an indefinite hang. Clearly this can be done by me putting it on a thread, and killing the process if required - but if library can do it...

err := script.Exec(cmd).WithTimeout(3*time.Second)
if err == script.Timeout {
   // do something
} else if err != nil {
    // do something else
}

s, err := script.Exec(cmd).WithTimeout(3*time.Second).Slice()
// Similar error handling as above

errbuf := new(bytes.Buffer)
p := script.NewPipe().WithStderr(errbuf).WithTimeout(3*time.Second)
result, err := p.Exec(cmd).<other methods>
// Similar error handling as above

[bitfield]

A context would be the more idiomatic way to do this, wouldn't it?

[rcowham]

A context would be fine - wasn't sure from reading other issues if that was the preferred way...

[bitfield]

Just a reminder that this is with you (or whoever wants to work on it) to complete the four steps I outlined.