On Thu, 8 Jan 2009, Edmund R. MacKenty wrote: > On Thursday 08 January 2009 14:13, John McKown wrote: > >Well, shoot. That never even occurred to me. What I thought that would do > >was: > > > >Change stderr to go where stdout currently goes, then change stdout to go > >into the pipe. I based this on the fact that if I do: > > > >command 2>&1 1>x.tmp > > > >Then stderr still comes to my terminal. It does not go to x.tmp. I guess > >there is some special code in bash to recognize the redirection & piping > >as "special". > > Actually, there's no special case for this. The rule is that the shell > processes I/O redirections left-to-right. The "2>&1" syntax just means" make > file descriptor 2 (stderr) refer to whatever file descriptor 1 (stdout) > refers to. It doesn't change stdout at all. File descriptor 1 already > refers to the pipe because the shell creates the pipes as it is parsing the > pipeline, before it parses the simple commands within the pipeline. > > I hope that makes sense! :-) > - MacK.
Ah! The little light goes on. That makes perfect sense. I was simply parsing the command from left to right, so that the redirection happened before the pipe, in my mind. -- Q: What do theoretical physicists drink beer from? A: Ein Stein. Maranatha! John McKown ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
