openssh bugs - Feb 2012 - [Bug 1983] New: add an option for disabling buffering

https://bugzilla.mindrot.org/show_bug.cgi?id=1983

             Bug #: 1983
           Summary: add an option for disabling buffering
    Classification: Unclassified
           Product: Portable OpenSSH
           Version: 5.9p1
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ssh
        AssignedTo: unassigned-bugs at mindrot.org
        ReportedBy: amcnabb at mcnabbs.org


Output is aggressively buffered when no pseudo-terminal is available.
For long-running commands, users have no way of checking how much
progress has been made, even if the command gives regular output. If
ssh had, say, a "LineBuffering" or "DisableBuffering"
option, then
users could control this behavior.

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
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                 CC|                            |djm at mindrot.org

--- Comment #1 from Damien Miller <djm at mindrot.org> 2012-03-09 10:11:15
EST ---
ssh generally tries to get data moved from its buffers at the earliest
possible time. What problem are you experiencing and can you provide a
recipe to reproduce it?

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Darren Tucker <dtucker at zip.com.au> changed:

           What    |Removed                     |Added
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                 CC|                            |dtucker at zip.com.au

--- Comment #2 from Darren Tucker <dtucker at zip.com.au> 2012-03-09
10:15:34 EST ---
Are you sure it's not the remote command that's causing the buffering? 
sshd will send output to the network as soon as it's available,
although it may get buffered in the TCP stack.

this:
$ ssh localhost "tty; while sleep 1; do date; done"

gives me "not a tty" and output at approximately 1 second intervals.

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--- Comment #3 from Andrew McNabb <amcnabb at mcnabbs.org> 2012-03-10
03:13:20 EST ---
I'm sorry; you're completely right. I should have looked into this a
bit more. I opened this because of a user report, and I should have
been more careful. It turns out that the user was running a Python
script, and Python buffers stdout aggressively by default. There are
easy workarounds, none of which involve changing the behavior of ssh.
:)  Sorry for the noise.

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WORKSFORME

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