Section: Administration Commands (8)Updated: March 2007Local indexUp
cereal-admin - administer cereal sessions
cereal-admin command [args]
cereal-admin is a program to administer cereal sessions. A
cereal session is a special (restricted) screen(1) session attached to
a serial terminal. Each cereal session is owned by a particular user
(USER) who is allowed to "attach" to the cereal screen session and
interact with the specified serial terminal via screen. Each cereal
session is also associated with a particular log group (LOGGROUP)
whose members are allowed to "follow" the logs of the session.
Cereal was designed to monitor serial lines connected to the serial
consoles of remote machines. The cereal system is outlined at:
Create a new session named SESSION on tty TTY, with baud rate BAUD.
USER is the user that will own the session, and LOGGROUP is the group
that will be able to follow the session non-interactively (ie. read
the logs). Once created, the session will be in a "stopped" state.
`c' may be used in place of `create'.
start [options] SESSION [SESSION]...
Start session(s). For each session specified, the session directory
is registered in the runsvdir directory. The screen session will be
attached to the serial terminal and logging of the terminal will
begin. `s' may be used in place of `start'. options: -a (--all) to
enable all sessions.
restart [options] SESSION [SESSION]...
Restart session(s). This sends running sessions a "restart" signal,
and starts session that are not running. This can be used when
changes have been made to the screenrc, for instance. `r' may be used
in place of `restart'. options: -a (--all) to disable all sessions,
-r (--running) to restart just the currently running sessions.
stop [options] SESSION [SESSION]...
Stop session(s). This kills the screen session attached to the serial
terminal by sending it an "exit" signal, and then unregistering the
session directory from the runsvdir directory. `k' may be used in
place of `stop'. options: -a (--all) to disable all sessions.
destroy [options] SESSION [SESSION]...
Destroy session(s) entirely. This will destroy the session directory,
including all history of the session and the logs. `d' may be used in
place of `destroy'. options: -a (--all) to remove all sessions.
List session(s). With no arguments, will list all sessions. The
leading three characters in the list indicate: whether the session is
running (+) or not (-) or in some unknown state (?), whether the user
can attach to the session (a) or not (-), whether the user can follow
the session (f) or not (-). If the session state is unknown (?), it's
usually because the user asking for information about the session
can't read the session stat file. `l' may be used in place of `list'.
Output a brief usage summary. `h' or `?' may be used in place of
Logs are handled by
For information on how to control session log handling, please see
svlogd(8) and/or log-limits.txt from the documentation of this
Default cereal screenrc file.
Configuration file to set parameters for session creation and
Special screenrc file for session SESSION. The presence of this file
overrides the default screenrc file /etc/cereal/screenrc.
Exit status is 0 if OK, 1 if minor problems, 2 if serious trouble.
Written by Jameson Rollins and Daniel Kahn Gillmor.
If the invoking user does not have read and execute access to the
cereal session's supervise directory, `cereal-admin list' may not
always indicate that session's status accurately.