Messages in this thread | | | Date | Wed, 06 May 2015 14:26:09 +0200 | From | "Michael Kerrisk (man-pages)" <> | Subject | Re: [PATCH man-pages] pty.7: clarify asynchronous nature of PTY IO. |
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Hi Neil,
On 05/06/2015 12:59 AM, NeilBrown wrote: > > A PTY is not like a pipe - there may be delayed between > data being written at one end and it being available at the other. > This became particularly apparent after > commit f95499c3030f ("n_tty: Don't wait for buffer work in read() loop") > > in Linux 3.12 > > Signed-off-by: NeilBrown <neilb@suse.de> > > ---
Thanks! Applied and tweaked a very little.
> Peter: does this seem reasonable and accurate to you?
I've got the patch sitting in a branch, in case Peter has suggestions for changes.
> MichaelK: Would you prefer the commit ID in the man page. It isn't so much > a deliberate change as a code improvement which caused problems for certain > use cases which depended on undefined behaviour. > Thread at https://lkml.org/lkml/2015/5/1/35
No, it's fine as is, thanks.
Cheers,
Michael
> diff --git a/man7/pty.7 b/man7/pty.7 > index 1332d11d9ca2..6c9ae182925c 100644 > --- a/man7/pty.7 > +++ b/man7/pty.7 > @@ -56,6 +56,12 @@ terminal emulators, > and > .BR expect (1). > > +Data flow between master and slave is handle asynchronously, much like > +data flow with a physical TTY. Data written to the slave will be > +available at the master promptly, but may not be available > +immediately. Similarly there may be a small processing delay between > +a write to the master, and the effect being visible at the slave. > + > Historically, two pseudoterminal APIs have evolved: BSD and System V. > SUSv1 standardized a pseudoterminal API based on the System V API, > and this API should be employed in all new programs that use >
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
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