Hi Chet, > > On 7/18/2011 10:14 AM, Ralph Corderoy wrote: > > > Is this happening because the built-in printf is using putchar(3) > > > in the PC() macro and stdio thinks file descriptor 1 is still to a > > > tty so it's persisting in line buffering? It would seem nicer if > > > fewer write(2)s were done when stdout isn't a tty, and not just > > > for UDP use. > > Almost exactly right, except replace "unbuffered" with "line-buffered > output". Bash uses stdio and sets stdout and stderr to line-buffered. > The advantage of fully-buffered mode shows itself when writing large > amounts of data, which the shell does not do very often. The > advantage of line-buffered mode is better response.
I see why it's line-buffered when writing to a terminal, but when bash changes where stdout points it has the option to setvbuf(3) or similar too based on what it knows about the destination, e.g. /dev/pts/3 versus /tmp/foo versus /dev/udp/0x7f000001/4242. Does it never do this then, and just leave things as line-buffered all the time? Cheers, Ralph.
