After talking with a coworker it seems that "grep" returns a \n after its
output. That was the bugger keeping my initial efforts from working.
On Friday, May 18, 2018 at 11:06:46 AM UTC-4, John Fox wrote:
>
> Drilling down farther for the heck of it
>
> os/exec/exec.go
> func (c *Cmd) Output() ([]byte, error) { if c.Stdout != nil {
>
> return nil, errors.New("exec: Stdout already set")
>
> }
>
> var stdout bytes.Buffer
>
> c.Stdout = &stdout
>
> captureErr := c.Stderr == nil
>
> if captureErr {
>
> c.Stderr = &prefixSuffixSaver{N: 32 << 10}
>
> }
>
> err := c.Run()
>
> if err != nil && captureErr {
>
> if ee, ok := err.(*ExitError); ok {
>
> ee.Stderr = c.Stderr.(*prefixSuffixSaver).Bytes()
>
> }
>
> }
>
> return stdout.Bytes(), err
>
> }
>
>
> stdout.Bytes() = bytes.Buffer.Bytes()
> bytes/buffer.go
>
> // Bytes returns a slice of length b.Len() holding the unread portion of the
> buffer.// The slice is valid for use only until the next buffer modification
> (that is,// only until the next call to a method like Read, Write, Reset, or
> Truncate).// The slice aliases the buffer content at least until the next
> buffer modification,// so immediate changes to the slice will affect the
> result of future reads.
> func (b *Buffer) Bytes() []byte { return b.buf[b.off:] }
>
> // A Buffer is a variable-sized buffer of bytes with Read and Write
> methods.// The zero value for Buffer is an empty buffer ready to use.
> type Buffer struct {
> buf []byte // contents are the bytes buf[off : len(buf)]
> off int // read at &buf[off], write at &buf[len(buf)]
> bootstrap [64]byte // memory to hold first slice; helps small buffers
> avoid allocation.
> lastRead readOp // last read operation, so that Unread* can work
> correctly.
> // FIXME: it would be advisable to align Buffer to cachelines to avoid
> false
> // sharing.
> }
>
> I am still not sure where the "10" or '\n' came from, but I know enough to
> get the program working. I am really enjoying getting to learn this language
> and excited for all that I can get it to do, even if it comes with the
> expected frustrations and head against wall banging.
>
>
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