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                      Bedrock Linux

Bedrock Linux 1.0beta2 Nyla

© Bedrock Linux 2012-2022
Linux® is a registered
trademark of Linus Torvalds

TODO: adjtime

Bedrock Linux 1.0beta2 Nyla Configuration Instructions


The rc.conf configuration file, located at /bedrock/etc/rc.conf, is used to populate a number of important environment variables.


TZ variable indicates timezone information. It can be in one of three forms:

Some software may ignore the TZ environment variable and instead attempt to read /etc/localtime to determine the current timezone. Bedrock Linux will copy /bedrock/etc/localtime to /etc/localtime when enabling a stratum to cover this possibility.


Sets the language/locale information.

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

Note locale information must be installed/generated in every statum, as it is currently set to local to avoid conflicts.


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=/opt/bin:/usr/local/bin:/usr/bin:/bin


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=/opt/sbin:/usr/local/sbin:/usr/sbin:/sbin


This is a list of directories used by the man executable to find man pages. If you alter this from the default, be sure to also change /bedrock/etc/brp.conf as well.

e.g. MANPATH="/usr/local/share/man:/usr/share/man"


This is a list of directories used by the info executable to find info documentation. If you alter this from the default, be sure to also change /bedrock/etc/brp.conf as well.

e.g. INFOPATH="/usr/local/share/info:/usr/share/info"


This is a list of directories that contain directories used by the freedesktop.org standard. For example, the items here could contain "icon" directories which contain icons to be used by GUI programs. For another example, it could contain an "applications" directory which contains .desktop files that are used to populate application menus and mime/default programs. If you alter this from the default, be sure to also change /bedroock/etc/brp.conf as well.

e.g. XDG_DATA_DIRS="/usr/local/share:/usr/share"

strata.conf and strata.d/*

Per-stratum configuration is read from /bedrock/etc/strata.conf and whatever files are found in /bedrock/etc/strata.d/. Typically most strata will use the same, default configuration. However, occasionally it is necessary or useful to adjust it, either for all stratum or just a handful of individual stratum.


share indicates a given path should be considered global, i.e. that everything should see the same set of files at any of these paths rather than their own version. New mount points in any of these directories will also be treated as global (mount --share'd). e.g.:

share = /proc, /sys, /dev, /home, /root, /lib/modules, /tmp, /var/tmp, /mnt
share = /media, /run


bind is similar to share except new mount points made under these directories are not treated as global. This is primarily used to avoid recursion where one global item is mounted within another. In general, anything set to be global in /bedrock should be bind'd rather than share'd. e.g.

bind = /bedrock, /bedrock/brpath, /bedrock/strata/bedrock

Careful with the order - directories should come before what they contain.


One cannot rename() the share or bind items. This is problematic for some files in /etc which (1) have neighboring items which are local (and so we cannot share all of /etc) and (2) which are updated via rename(). Any files which hit the above two situations should be union'd. One can break up share and bind items if the lines get to long, but union items have a picky syntax; keep all of the items that are contained in the same directory on the same line. e.g.:

union = /etc: profile, hostname, hosts, passwd, group, shadow, sudoers, resolv.conf, machine-id, shells, systemd/system/multi-user.target.wants/bedrock.service, locale.conf, motd, issue, os-release, lsb-release, rc.local


Bedrock Linux has hooks to run executables before/after enabling/disabling a stratum. If you would like to do something such as ensure a stratum-specific mount point is mounted before enabling a stratum, these hooks could be utilized to achieve this. For example, you could check if an NFS mount point is mounted on /bedrock/strata/networked-stratum and, if it is not, mount it just before enabling the stratum. You could then unmount it when disabling the stratum. e.g.:

preenable = /bedrock/share/brs/force-symlinks
preenable = /bedrock/share/brs/setup-etc
preenable = /bedrock/share/brs/run-lock


enable indicates if the given stratum should be enabled at boot time. This can either be boot (indicating it should be enabled at boot time) or manual (indicating it will be enabled/disabled manually). e.g.

enable = boot

If multiple enable items are set, the latest one takes precidence. Thus, one can include enable = boot in a framework (frameworks described below) and then override it with a stratum-specific enable = manual.

Generally one would want enable = boot; however, if some stratum is rarely used it may be best left to manual.


init indicates the given stratum can provide an init system. The value should be the command to run at boot if this stratum is chosen to provide init. The value is the entire line after the =; do not place multiple init commands in the same line separated by ,'s as one can do with share. Historically, /sbin/init is utilized as the command to run the init; however, systemd systems seem to prefer /lib/systemd/system without a corresponding symlink at /sbin/init. e.g.:

init = /sbin/init

Note multiple init values can be provided if a given stratum provides multiple init systems; all of the resulting values will be listed in the init-selection menu.


When enabling a stratum, Bedrock Linux will mount some filesystems (e.g. from other stratum.conf settings such as share), and then proceed to unmount filesystems when disabling the stratum. To manage this sanely, Bedrock Linux expects the stratum to have no mount points when disabled.

If there is some exception where Bedrock Linux should accept a pre-existing mount point when enabling a stratum, or leave some mount point mounted when disabling a stratum, this can be indicated via the unmanaged setting. For example, of a stratum's root directory is mounted over NFS, one could indicate Bedrock Linux should not touch a mount point at root via:

unmanaged = /

Nonetheless it is useful to manage such mount points, e.g. ensure the NFS mount is mounted at stratum enable. To do this use the preenable and postdisable hooks.


"framework" is used to inherit settings placed in /bedrock/etc/frameworks.d/framework-name. This is useful to avoid excessive repetition when multiple strata share the same settings. e.g.

framework = default

Most strata should use framework = default, with the notable exception of the global stratum which should use framework = global.

aliases.conf and aliases.d/*

Aliases can be created for strata. In most contexts the alias can be used in place of the stratum, e.g. with brc and bri. Bedrock Linux requires some aliases for tracking singleton strata, but you are free to create others to your liking.

Alias information is read from /bedrock/etc/aliases.conf and from the files found in /bedrock/etc/aliases.d/. Simply indicate the desired alias name followed by an = and then the stratum it is aliased to. For example, Debian releases are often referred to by their current state in the development process in addition to their name. Thus:

oldstable = wheezy
stable    = jessie
testing   = stretch
unstable  = sid

When stretch becomes stable, the aliases can be adjusted accordingly so "stable" points to the new stable release.


The file at /bedrock/etc/brp.conf is responsible for managing the filesystem at /bedrock/brpath filesystem which is the underlying mechanism for the implicit access rules. The brpath filesystem is used to make files from other strata accessible, altering them as necessary so things "just work". If any strata provides a file, this file could be made accessilbe through the /bedrock/brpath filesystem for the other strata.

The [pass], [brc-wrap] and [exec-filter] headings should contain key-value pairs separated by an equals sign. The keys will indicate files/directories that should show up at /bedrock/brpath, and the values will indicate files/directories that will be unioned to populate the mount point's files.

For the keys, a trailing "/" indicates the item should be a directory (and thus the values will be used to populate files in the directory). Otherwise, the item is treated as a file and the values indicate possible files it could represent.

For the values, a prefixed stratum (e.g. "stratum:/path/to/file") indicates the value corresponds to that specific stratum's file/directory. Otherwise, all of the enabled strata will be searched as possible sources for the file.

The [stratum-order] heading should be followed by a list of strata, one per line. These indicate the priority order for values that do not have a stratum: prefix. Note this does not have to be an exhaustive list - any enabled strata not listed will still be used; they will simply be treated as lower priority than the those listed.

An example brp.conf:

# Nothing special with this "pass" category, it just passes files through
# untouched.
/man/      = /usr/local/share/man,   /usr/share/man
/info/     = /usr/local/share/info,  /usr/share/info
/icons/    = /usr/local/share/icons, /usr/share/icons
/firmware/ = /lib/firmware
/zoneinfo/ = /usr/share/zoneinfo

# This will wrap all items it finds in a script that calls brc to set the local
# context.  This is important for executables to "just work".
/bin/  = /usr/local/bin,  /usr/bin,  /bin
/sbin/ = /usr/local/sbin, /usr/sbin, /sbin

# By convention, items in "/pin/" are given a higher priority than even local
# files.  This is used, for example, to ensure a given executable which is
# strongly related to the init system is always tied to the init system.
/pin/bin/systemctl  = init:/usr/bin/systemctl,  init:/bin/systemctl
/pin/bin/rc-service = init:/usr/bin/rc-service, init:/bin/rc-service
/pin/bin/rc-status  = init:/usr/bin/rc-status,  init:/bin/rc-status
/pin/bin/rc-update  = init:/usr/bin/rc-update,  init:/bin/rc-update

/pin/sbin/poweroff   = init:/usr/sbin/poweroff,   init:/sbin/poweroff, init:/usr/bin/poweroff, init:/bin/poweroff
/pin/sbin/reboot     = init:/usr/sbin/reboot,     init:/sbin/reboot,   init:/usr/bin/reboot,   init:/bin/reboot
/pin/sbin/shutdown   = init:/usr/sbin/shutdown,   init:/sbin/shutdown, init:/usr/bin/shutdown, init:/bin/shutdown
/pin/sbin/halt       = init:/usr/sbin/halt,       init:/sbin/halt,     init:/usr/bin/halt,     init:/bin/halt
/pin/sbin/systemctl  = init:/usr/sbin/systemctl,  init:/sbin/systemctl
/pin/sbin/rc-service = init:/usr/sbin/rc-service, init:/sbin/rc-service
/pin/sbin/rc-status  = init:/usr/sbin/rc-status,  init:/sbin/rc-status
/pin/sbin/rc-update  = init:/usr/sbin/rc-update,  init:/sbin/rc-update

# This will modify some of the fields in the freedesktop standard .desktop
# items to fix local context issues.
/applications = /usr/local/share/applications, /usr/share/applications

# Add strata here in the order you want them to take priority when multiple
# ones provide a file.  One stratum per line.


strata.conf/strata.d/ indicates which init system(s) a given stratum can provide, if any. The user is then (optionally) prompted during boot to chose which of them to use for the given session. /bedrock/etc/brn.conf can be used to configure a default stratum/command pair for init as well as a timeout for the init selection menu.

timeout indicates the amount of time, in seconds, the user is provided to make a selection before the default is automatically chosen. Set to 0 to indicate no time should be provided - always boot directly into the configured default. Set to -1 to indicate no time limit - nothing will be chosen automatically, the user has as much time as desired.

To chose a default stratum, set the default_stratum = and default_cmd items accordingly. With those set, a user can simply hit enter at the menu and the default item will be chosen. Moreover, if a timeout is set, the default item will be chosen when the timeout expires.


The content below revolves around three configuration files:

The first - /etc/fstab - is global by default. If you are editing it at install time - when you're not yet actually running Bedrock Linux - the file may be at $GLOBAL/etc/fstab (e.g. /bedrock/strata/global/etc/fstab), and not directly at /etc/fstab quite yet. The latter two should be at /bedrock/etc/fstab irrelevant of the circumstances: either you're hijacking such that it is on the root, or you're doing a manual install and have made a symlink for /bedrock.

Bedrock Linux provides a menu on boot to let the user choose which init system to use for the given session. Naturally this menu must be provided before the init system is run, which means it must be provided before /etc/fstab is parsed by the init system. If the init system is on a partition other than the boot-time root partition, this partition must be mounted by something other than /etc/fstab. For these mounts Bedrock Linux provides its own pre-init time fstab file at /bedrock/etc/fstab.

Some users prefer to make a partition specifically for /bedrock/strata or one for each strata within /bedrock/strata (e.g. a partition for /bedrock/strata/gentoo, a partition for /bedrock/strata/slackware, etc). Since these partitions can potentially contain init systems, /bedrock/etc/fstab was created specifically to support these workflows. If you do not have special partitions for/within /bedrock/strata, but rather kept that directory on the root partition, you probably do not need to worry about /bedrock/etc/fstab. However, you may still need to worry about the default framework - keep reading below.

Other common mount points - such as /home and /tmp - can use /etc/fstab just as they are utilized in other distros. Nonetheless, if you would like to have /bedrock/etc/fstab mount partitions such as /home it can do so.

Be sure not to include the same mount item in both /etc/fstab and /bedrock/etc/fstab - any given mount should only appear in one or the other. When you place anything in /bedrock/etc/fstab make sure you do not also have it within /etc/fstab.

For the most part, /bedrock/etc/fstab utilizes the same syntax as the typical /etc/fstab. However, there are a few special things to keep in mind for /bedrock/etc/fstab:

Additionally, the default framework should be made aware of some of these additional mount points; place such changes into /bedrock/etc/frameworks.d/default. Any mount points in /bedrock/ should be configured as bind items. For example, if you made /bedrock/strata its own partition, add

bind = /bedrock/strata

and the /bedrock/strata mounted in in /bedrock/etc/fstab will be made accessible in the other strata. Careful not to double up - ensure there is only one bind item for any given bind directory. For example, by default Bedrock Linux is configured with a bind item for /bedrock/run - no need to make another one for that directory.

Any mount global mount points should be configured as share items. For example, if you made /var/log its own partition and wish for it to be considered global, add

share = /var/log

to the default framework. Again, careful not to double up - ensure there is only one instance of any given share item. For example, /home should be configured as a share item by default and should not be added again.