os/exec: Stdout/Stderr doc cleanup.

Following comments on CL 76320.

Breaks Cmd.Std{out,err} doc into three paragraphs and updates Cmd.Stdin
formatting to match.

Fixes an erroneous reference to Stdin in the output goroutine comment, while
keeping the wording consistent between Stdin and Stdout/Stderr.

Change-Id: I186a0e2d4b85dfb939443a17e62a1eb2ef64b1bf
Reviewed-on: https://go-review.googlesource.com/79595
Reviewed-by: Rob Pike <r@golang.org>

diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index 4a5789647fa098ca307b61ae4b4c53373f7e1f6b..8a49fe3b58eb68889225e8395360348859f0beae 100644 (file)
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -77,9 +77,12 @@ type Cmd struct {
        Dir string
 
        // Stdin specifies the process's standard input.
+       //
        // If Stdin is nil, the process reads from the null device (os.DevNull).
+       //
        // If Stdin is an *os.File, the process's standard input is connected
        // directly to that file.
+       //
        // Otherwise, during the execution of the command a separate
        // goroutine reads from Stdin and delivers that data to the command
        // over a pipe. In this case, Wait does not complete until the goroutine
@@ -92,14 +95,13 @@ type Cmd struct {
        // If either is nil, Run connects the corresponding file descriptor
        // to the null device (os.DevNull).
        //
-       // If either is an *os.File, the process's standard output or standard
-       // error, respectively, are connected directly to that file. Otherwise,
-       // if either is not nil, during the execution of the command a separate
-       // goroutine reads from the process's standard output or standard error
-       // and delivers that to Stdout or Stderr. In this case, Wait does not
-       // complete until the goroutine stops copying, either because it has
-       // reached the end of Stdin (EOF or a read error) or because writing to
-       // the pipe returned an error.
+       // If either is an *os.File, the corresponding output from the process
+       // is connected directly to that file.
+       //
+       // Otherwise, during the execution of the command a separate goroutine
+       // reads from the process over a pipe and delivers that data to the
+       // corresponding Writer. In this case, Wait does not complete until the
+       // goroutine reaches EOF or encounters an error.
        //
        // If Stdout and Stderr are the same writer, and have a type that can
        // be compared with ==, at most one goroutine at a time will call Write.