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