On Saturday, February 19, 2011 1:50:43 pm Jeremie Le Hen wrote: > Hi, > > I've been annoyed multiple time when running a command such like > iostat -x 1 | grep -v ad10 | cat -n > > The problem stems from two factors: > - grep's stdio sees that its stdout is not a terminal, so stdout is > full buffered and not line-buffered; > - iostat produces output too slowly so the aforementioned buffer takes > numerous seconds to be filled and flushed to the last command. > > This problems is not specific to FreeBSD, it is actually a consequence > of POSIX specification. I've checked this on Solaris and Linux. > > I've attached a small patch for stdio, so if the environment variable > STDIO_IOLBF is set, the output streams will be line-oriented by default. > iostat -x 1 | env STDIO_IOLBF=1 grep -v ad10 | cat -n > > Before send it as a PR, I would like to hear your comments about this, > especially: > - the variable name (no bikeshed please, I just ask this if there is a > naming convention I'm not aware of); > - the documentation: I've put a hint in stdio(3) manpage and put the > full explanation in setvbuf(3).
Many people would find this useful I think. -- John Baldwin _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
