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:


cereal-admin takes various subcommands:


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]...

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 `help'.


Logs are handled by svlogd. For information on how to control session log handling, please see svlogd(8) and/or log-limits.txt from the documentation of this package.



Default cereal screenrc file.


Configuration file to set parameters for session creation and management.


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.


Report bugs to <[email protected]>.


Copyright © 2007 Jameson Rollins and Daniel Kahn Gillmor

This is free software. You may redistribute copies of it under the terms of the GNU General Public License <>. There is NO WARRANTY, to the extent permitted by law.

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