os/exec: StdoutPipe example fails when run on golang.org

[stevekuznetsov]

On the official doc, the example under func (*Cmd) StdoutPipe fails with error: 2009/11/10 23:00:00 exec: "echo": executable file not found in $PATH when run.

[ianlancetaylor]

What operating system are you using?

[stevekuznetsov]

I'm in Fedora 22 but to be clear this is the embedded example in the web page that fails, not me running anything locally.

[ianlancetaylor]

Ah, I see. Yes, none of the os/exec examples will actually work in the limited environment of the Go playground. We should try to document that somehow.

[odeke-em]

I have a few ideas to help solve this

1. We can document this for each example ie

// Note: This example when run in the playground
// will fail because the playground is sandboxed/limited
// so shell utility lookups will fail.

2a) Easily detect when we are running on the playground like this

import "runtime"

func execPathsUnavailable() bool {
     // Shell lookups and utilities are
     // unavailable on the playground running nacl
     return runtime.GOOS == "nacl"
}

2b) A little more complex:

• Use the execPathsUnavailable() when extracting each example in exec/ detect and inject that comment in (1) before the body of each example.

Please let me know what you think would be a better option. Thanks.

[minux]

os/exec is unavailable in nacl, we could just make the error from os/exec better on nacl.

[stevekuznetsov]

Could the 'run' button for the examples be removed or disabled?

[gopherbot]

CL https://golang.org/cl/18035 mentions this issue.

[bradfitz]

@stevekuznetsov, yes, that's probably the right answer.

If we don't want to invent new annotation syntax, we could even just have a blacklist of code samples in hard-coded in cmd/godoc. If an example is on the blacklist then it'd get to Run button.

[minux]

We just need to blacklist the os/exec package to start with.

[rsc]

If you're running your own godoc then the example runs fine, right?

[gopherbot]

CL https://golang.org/cl/18315 mentions this issue.