plan9-gpl/sys/man/4/consolefs

.TH CONSOLEFS 4
.SH NAME
consolefs, C, clog  \- file system for console access
.SH SYNOPSIS
.B aux/consolefs
[
.B -m
.I mntpt
] [
.B -c
.I consoledb
]
.PP
.B C
.I system
.PP
.B aux/clog
console log
.I system
.SH DESCRIPTION
To ease administration of multiple machines one might attach
many serial console lines to a single computer.
.I Consolefs
is a file system that lets multiple users simultaneously access
these console lines.
The consoles and permissions to access them are defined in the
file
.I consoledb
(default
.BR /lib/ndb/consoledb ).
The format of
.I consoledb
is the same as that of other
.B /lib/ndb
files,
.IR ndb (6).
Consoles are defined by entries of the form:
.PP
.EX
	console=dirty dev=/dev/eia205
		uid=bignose
		gid=support
		speed=56200
		cronly=
.EE
.PP
Each
.IR console / dev
pair represents the name of a console and the device
associated with it.
.I Consolefs
presents a single level directory with up to three files
per console:
.IR console ,
.IB console ctl\f1,
and
.IB console stat\f1.
Writes of
.I console
are equivalent to writes of
.I dev
and reads and writes of
.IB console ctl
and 
.IB console stat
are equivalent to reads and writes of
.IB dev ctl
and
.IB dev stat
respectively.
.IB Console ctl
and
.IB console stat
will not exist if the underlying
.I dev
does not provide them.
.I Consolefs
broadcasts anything it reads from
.I dev
to all readers of
.IR console .
Therefore, many users can
.IR con (1)
to a 
.IR console ,
see all output, and enter commands.
.PP
The
.I cronly=
attribute causes newlines typed by the user to be sent to
the console as returns.
The
.I speed=x
attribute/value pair specifies a bit rate for the
console.  The default is 9600 baud.
The
.I openondemand=
attribute causes the console device
.RI ( dev )
to be opened only when the corresponding
.IB mntpt / console
file is open.
.PP
Access to the console is controlled by the
.I uid
and
.I gid
attributes/value pairs.
The uid values are user account names.
The gid values are the names of groups defined in
.I consolefs
by entries of the form:
.PP
.EX
	group=support
		uid=bob
		uid=carol
		uid=ted
		uid=alice
.EE
.PP
Groups are used to avoid excessive typing.  Using
.I gid=x
is equivalent to including a
.I uid=y
for each user
.I y
that is a member of
.IR x .
.PP
To keep users from inadvertently interfering with one another,
notification is broadcast to all readers whenever a user
opens or closes
.IR name .
For example, if user
.B boris
opens a console that users
.B vlad
and
.B barney
have already opened, all will read the message:
.PP
.EX
	[+boris, vlad, barney]
.EE
.PP
If
.B vlad
then closes,
.B boris
and 
.B barney
will read:
.PP
.EX
	[-vlad, boris, barney]
.EE
.PP
.I Consolefs
posts the client end of its 9P channel in
.BR /srv/consolefs
and mounts this locally in
.I mntpt
(default
.BR /mnt/consoles );
remote clients must
.B mount
(see
.IR bind (1))
this file to see the consoles.
.PP
The
.IR rc (1)
script
.B C
automates this procedure.
It uses
.IR import (4)
to connect to
.B /mnt/consoles
on the machine connected to all the consoles, then uses
.IR con (1)
to connect to the console of the machine
.IR system.
The script must be edited at installation
by the local administration to identify the
system that holds
.BR /mnt/consoles .
.PP
.I Aux/clog
opens the file
.I console
and writes every line read from it, prefixed
by the ASCII time to the file
.IR log .
.PP
An example of 2 consoles complete with console logging is:
.IP
.EX
% cat /lib/ndb/consoledb
group=sys
	uid=glenda
console=bootes dev=/dev/eia0 gid=sys
console=fornax dev=/dev/eia1 gid=sys
% aux/consolefs
% ls -p /mnt/consoles
bootes
bootesctl
fornax
fornaxctl
% clog /mnt/consoles/fornax /sys/log/fornax &
% clog /mnt/consoles/bootes /sys/log/bootes &
.EE
.PP
The console server's default name space must 
mount the consoles for 
.I C
to import.
This can be arranged by adding
.IP
.EX
mount /srv/consoles /mnt/consoles
.EE
.LP
to
.BR /lib/namespace.$sysname .
.SH FILES
.TF /lib/ndb/consoledb
.TP
.B /srv/consoles
Client end of pipe to server.
.TP
.B /mnt/consoles
Default mount point.
.TP
.B /lib/ndb/consoledb
Default user database.
.SH SOURCE
.B /sys/src/cmd/aux/consolefs.c
.br
.B /rc/bin/C
.br
.B /sys/src/cmd/aux/clog.c
.SH BUGS
.PP
Changing the gid's or uid's while
.I consolefs
is running
is detected by
.IR consolefs .
However, to add new consoles
one must restart
.IR consolefs .