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Bedrock Linux 1.0alpha4 Flopsie

Bedrock Linux 1.0alpha4 Flopsie Configuration Instructions

rc.conf

The rc.conf configuration file covers the general system-wide configuration options, especially boot configuration options. It is located at /bedrock/etc/rc.conf. It is sourced as a bourne shell script, so be careful with your syntax - there should be no spaces around the equals signs used for establishing a setting. Change the text to the right of the equals sign to set the value.

TZ

Sets timezone using the POSIX TZ environmental variable standard. For details on the nuances of the POSIX TZ environmental variable, see:

e.g.: TZ=EST+5EDT,M3.2.0/2:00:00,M11.1.0/2:00:00

HWCLOCK

Sets whether the hardware clock is set to local time or UTC. Traditionally UNIX systems use UTC, but Windows uses local. If you are dual-booting with Windows, local may be preferable. Set to LOCAL or UTC accordingly.

e.g.: HWCLOCK=UTC

LANG

Sets the language/locale information.

e.g.: LANG=en_US.UTF-8

FSCK

if FSCK=1, Bedrock will attempt to run fsck at boot. Otherwise, Bedrock will skip running fsck at boot. If you are using an initrd which runs fsck, it could be beneficial to set FSCK=0 to avoid running fsck twice at boot.

e.g.: FSCK=1

NPATH

Sets the normal user POSIX PATH variable. These are the directories in which programs look for executables. If you aren't sure what to put here, you almost certainly want the value in the example below. Note that /etc/profile (which should be sourced by your shell when it starts) will add items to the beginning and end of this variable to make it play with Bedrock specific functionality.

e.g.: NPATH=/usr/local/bin:/usr/bin:/bin

SPATH

Sets additional directories for the super user's (aka root's) POSIX PATH variable. Same general idea as above, but for the root user who probably needs access to the s* directories that the non-root user does not.

e.g.: SPATH=/usr/local/sbin:/usr/sbin:/sbin

clients.conf

The existence of a (root owned, non-root-unwritable) file at

/bedrock/etc/clients.d/clientname.conf

indicates configuration for an (enabled) client. If the filename is, instead,

/bedrock/etc/clients.d/clientname.conf.disabled

then the client is considered disabled (so one cannot use it with brc). However, it will contain configuration necessary to re-enable it (with brs).

General Format

The contents of the configuration files are simply a series of "key = value" lines. Blank lines and lines starting with "#" are ignored. Baring newlines, it is flexible about whitespace.

There are three recognized keys in Bedrock Linux 1.0alpha4 Flopsie: "bind", "union", and "framework".

Bind

Most of any given client's files are separated from the rest of the system via chroot. This way they will not conflict with each other. However, many things should be shared between clients to ensure they can interoperate with other clients, such as /home and /tmp. "bind" items are lists of files and directories which the given client should share with the rest of the system via bind-mounts.

The values on the right side of the equals sign can be comma separated to list multiple items per line.

There are two things to keep in mind when using bind items:

Example:

bind = /proc, /sys, /dev, /dev/pts, /dev/shm, /bedrock
bind = /bedrock/clients/bedrock, /home, /root, /lib/modules, /tmp, /var/tmp

Union

Union is similar in purpose to bind. However, it is different in two ways:

Thus, the majority of shared items should use bind (to maximize performance), except those which need to be updated via rename().

The first item on the right side of the equals sign should be the directory containing the item(s) to be shared, followed by a colon, followed by a comma-separated list of items to be shared relative to the first item without a starting slash. This may be better explained with examples, see below.

Note that the first item listed is a mount point. One cannot use two union items on the same directory or the latter one will be mounted over the former and the former will be inaccessible. Instead, combine them into one line.

Example:

union = /etc: profile, hostname, hosts, passwd, group, shadow, sudoers, resolv.conf

Framework

Multiple clients will likely share similar if not identical bind/union settings. Instead of duplicating many settings, a framework can be used to indicate that a collection of settings stored in

/bedrock/etc/frameworks.d/frameworkname

are to be utilized. Frameworks have the exact same syntax as normal client.conf files (and can refer to each other). Typical Bedrock Linux systems may have one or two frameworks which most client configurations utilize.

A reference framework with recommended defaults for most clients should be available by default at

/bedrock/etc/frameworks.d/default

Example:

framework = default

Following is a list of the files and directories which you should consider for the "bind" and "union" settings in your clients and frameworks. This is not exhaustive - if you can think of something else you would like to share, feel free to do so. Moreover, if you disagree with the recommendation and feel you understand the repercussions of not sharing something, you may skip sharing these directories. Do not blindly take values from this, as many of this are potentially problematic - these are recommended for consideration for use rather than necessarily for use.

The following directories are expected to be set up by many programs which require them for basic functionality. You almost certainly want these for all of your clients.

bind = /proc, /dev, /dev/pts, /sys

The following should be shared in any client that should be able to run commands in other clients. If you are attempting to set up a limited client without such functionality, this can be skipped.

bind = /bedrock, /bedrock/clients/bedrock
union = /etc: /etc/profile

Many programs create temporary files in these directories. These files are often used to communicate with other programs. To ensure these inter-program communication function across clients, you should share these directories.

bind = /tmp, /var/tmp, /dev/shm

Note that "/dev/shm" should be after "/dev" if you are sharing "/dev".

Most of the user-specific files will be in /home and, for the root user, /root. You probably want these shared across clients.

bind = /home, /root

Some programs will expect these files to be populated. Note that you do not necessarily have to make these the same in all clients, but if you cannot think of a reason to differentiate them, it is probably best to ensure they are the same.

union = /etc: hostname, hosts

The modules for the Linux kernel are traditionally kept in /lib/modules. If multiple clients would like to load these modules (or install non-upstreamed modules), the directory should be shared with all clients. Note that some Linux distributions are moving these to /usr/lib/modules, now, and leaving a symlink at /lib/modules pointing accordingly. This should not be a problem so long as the symlink is there. However, if you have multiple clients which use the same name for their kernels which attempt to install modules there could be a conflict. This is unlikely if you do not use multiple clients of the same distro/release which all have the kernel/modules packages installed, but is something to be careful about nonetheless. If you are using a kernel from a client, you almost certainly want to share this directory with at least that client.

bind = /lib/modules

Like /lib/modules, sharing this directory could be useful if you are using a kernel from a client so the client can keep the kernel you are using up to date. However, this also means if that client or another client which also shares /boot has a problem or there is a conflict, it could potentially make your system unbootable. There also are not very many benefits to sharing this with clients which will not have their kernels used for booting. It might be safest to simply manually copy the kernel files from the /boot of the respective clients into the core where they are out of reach of the client's package managers.

bind = /boot

Like /lib/modules and /boot, it can be useful to use a client's /lib/firmware if you are also using its kernel. However, this can easily conflict with other clients. In general, it is probably best to simply copy files from clients into the core Bedrock's /lib/firmware.

bind = /lib/firmware

Bedrock Linux as a client

There should be a file at /bedrock/clients/bedrock.conf to ensure bedrock is recognized as a client for commands such as bri and poweroff to work. This file can be empty.

Additionally, the root directory should be bind-mounted into /bedrock/clients (as is done in the default /etc/fstab). See the fstab configuration section.

Full Example

framework = default

or

bind = /proc, /sys, /dev, /dev/pts, /dev/shm, /bedrock
bind = /bedrock/clients/bedrock, /home, /root, /lib/modules, /tmp, /var/tmp
union = /etc: profile, hostname, hosts, passwd, group, shadow, sudoers, resolv.conf

udev

By default, Bedrock Linux uses mdev rather than udev. If you would like to use udev instead, ensure you have udev in a client, then do the following:

The next time you reboot, udev should replace mdev.

To replace mdev with udev in the current session without rebooting, simply run sh /etc/init.d/rcS.udev.

fstab

For the most part, this is a /etc/fstab file such as you would find in any other Linux distribution, and documentation for those distributions should apply here as well. This file is primarily used for mounting partitions at boot or setting up the functionality for devices to be easily mounted by an end-user, such as optical drives.

However, there are a few additional things to note:

.brsh.conf

To use the Bedrock Linux meta-shell brsh, create a file in your home directory called .brsh.conf which contains the contents that should be in your $SHELL environment. For example, if you would like to use bash, have ~/.brsh.conf contain just:

/bin/bash

rcS.clients and rcK.clients

To have a client daemon start or stop at boot/shutdown, place the relevant command to do this in /etc/init.d/rcS.clients and /etc/init.d/rcK.clients, respectively. For example, to start Debian squeeze's cups daemon at boot, place the following in your /etc/init.d/rcS.clients:

brc squeeze /etc/init.d/cups start

And, to ensure it properly closes at shutdown, place the following in your /etc/init.d/rcK.clients:

brc squeeze /etc/init.d/cups stop

brp.conf

To specify client priority order for the brp utility, add the clients in the desired order, one per line, in /bedrock/etc/brp.conf.

If a given command is not available in the local client, but is available in another client, and brp has been run, the highest-listed client in brp.conf will indicate which client will provide the command. If no client which provides the command is listed in brp.conf, but there are clients which provide the command, the first one listed by bri -l will provide the command.

For example: - client "debian" does not have command gparted - both clients "arch" and "fedora" have gparted - if arch or fedora runs gparted, each will see their own version of gparted. - if debian runs gparted, it will either run arch's or fedora's, depending on which is listed higher within brp.conf. If neither is listed, the first one listed by bri -l will be chosen.