Causing a "dying gasps from server unexpected"

[Sebastiano Vigna]

I had the problem above with CVS; eventually I discovered it was caused by
external interferences, but since the problem is marked as "if you have
discovered information concerning its cause, please let us know", here's my
.02$:

I use a program called "lifekeeper"
(http://gongolo.usr.dsi.unimi.it/~vigna/lifekeeper/) to keep NAT firewalls
from shutting down idle ssh connections. The program runs in the background
and prints an ASCII NUL every 30s. This keeps the connection alive and has
no visual effect.

However, in my shell startup files I check $PS1 to determine whether the
shell is interactive before starting lifekeeper. I installed erroneously the
check after setting PS1 to a non-empty string, so lifekeeper was started on
*all* shells. As a result, secure shell connections used by CVS had a NUL
dropping every 30s in the middle of stdout. These reproducibly caused the
problem above.

It is likely that anyone starting in the background programs that emit some
output (say, a start message) can experience an analogous behaviour. This of
course is not a problem with cvs--rather, with the user setup, but maybe it
is worth mentioning in the docs.

Greetings,

                                        seba