document this issue as a "common issues".

I'm not sure entirely how common this is,
as somebody who runs into the issue, this might
be the first place I'd look ..

diff --git a/doc/commonissues.rst b/doc/commonissues.rst
index 2efae46c16ad618f88ad6e3057c5d73ab10f6209..67985d04b10a1acce3fc589ef0ae9a271ec10913 100644 (file)
--- a/doc/commonissues.rst
+++ b/doc/commonissues.rst
@@ -101,3 +101,15 @@ The only solution I have found is to use public key authentication with SSH.
 This bypasses the need for a password. I'm not happy with this solution. The
 problem is due to poor support for Solaris Pseudo TTYs in the Python Standard
 Library.
+
+child input not fully received
+------------------------------
+
+You may notice when running for example cat(1) or base64(1), when sending a
+very long input line, that it is not fully recieved, and the BEL ('\a') is
+found in output.
+
+By default the child terminal matches the parent, which is often in "canonical
+mode processing". You may wish to disable this mode. The exact limit of a line
+varies by operating system, and details of disabling canonical mode may be
+found in the docstring of :meth:`~pexpect.spawn.send`.