NAME
logd - job output logging daemon
SYNOPSIS
logd [OPTION]...
DESCRIPTION
logd
is started by
init(8)
to receive the output of jobs with
console logged
in their job definition, which is the default if no other
console
setting is given.
Output is timestamped and written, with the job name, to
/var/log/boot
or stored in memory until the file is writable.
OPTIONS
--daemon
Detaches from the terminal and runs in the background.
STARTUP
To eliminate race conditions on startup, such as not being ready to receive
connections when the first job is started, the following procedure is used.
Once ready to receive connections,
logd
raises the
SIGSTOP
signal, putting itself to sleep until continued by another process.
After starting
R logd ,
init(8)
waits for the process to stop if it hasn't already, and then sends it the
SIGCONT
signal so that it can proceed. Only once this has happened, will
init(8)
start other jobs.
When the
--daemon
option is given, this is not performed; instead
logd
will not detach from the console until it is listening on the socket.
SOCKET PROTOCOL
logd
listens on a
unix(7)
stream socket in the abstract namespace, bound to
R /com/ubuntu/upstart/logd .
init(8)
opens a new connection for each job that is to be logged, binding the
socket to the standard input, output and error file descriptors for the job.
Before running the job, it sends the job name on the socket so that it can be
logged along with the messages. This is sent as a
size_t
that contains the length of the name to read, followed by that many
character bytes. The NULL terminator is not sent as part of the protocol,
it is up to the receiver to add that if required.
Further information about the job, such as its description, can be obtained
by opening an ordinary connection to the
init(8)
daemon and querying it using the name received.
AUTHOR
Written by Scott James Remnant.
REPORTING BUGS
Report bugs at https://launchpad.net/products/upstart/+bugs
COPYRIGHT
Copyright 2006 Canonical Ltd.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
