services: Use system groups where applicable.

* gnu/services/avahi.scm (avahi-service): Add 'system?' field to
  'user-group' form.
* gnu/services/base.scm (guix-service): Likewise.
* gnu/services/dbus.scm (dbus-service): Likewise.
* gnu/services/networking.scm (tor-service): Likewise.

system: Recognize more file system flags.

* guix/build/linux-initrd.scm (MS_NOSUID, MS_NODEV, MS_NOEXEC): New
  variables.
  (mount-flags->bit-mask): New procedure.
  (mount-file-system)[flags->bit-mask]: Remove.
  Use 'mount-flags->bit-mask' instead.
  In /etc/mtab, use the empty string when OPTIONS is false.
* gnu/services/base.scm (file-system-service): Add #:flags parameter and
  honor it.
* gnu/system.scm (other-file-system-services): Pass FLAGS to
  'file-system-service'.

system: Add 'file-system' decl. for /dev/pts, and use the right options.

Fixes <http://bugs.gnu.org/18081>.

* gnu/system/file-systems.scm (%devtmpfs-file-system): Add
  'needed-for-boot?' field.
  (%tty-gid, %pseudo-terminal-file-system): New variables.
  (%base-file-systems): Add %PSEUDO-TERMINAL-FILE-SYSTEM.
* gnu/services/base.scm (udev-service): Remove dependency on
  'file-system-/dev'.
* gnu/system/shadow.scm (%base-groups): Add 'id' field for group 'tty'.
* guix/build/linux-initrd.scm (boot-system): Remove 'mount' call for
  /dev/pts.
* doc/guix.texi (File Systems): Add %pseudo-terminal-file-system.

system: Add 'create-mount-point?' file system option.

* gnu/system/file-systems.scm (<file-system>)[create-mount-point?]: New
  field.
* gnu/services/base.scm (file-system-service): Add #:create-mount-point?
  parameter and honor it.
* gnu/system.scm (other-file-system-services): Update
  'file-system-service' call accordingly.
* doc/guix.texi (File Systems): Document it.

system: Add '%devtmpfs-file-system' for udev, and '%base-file-systems'.

Suggested by Adam Pribyl <pribyl@lowlevel.cz>.

* gnu/services/base.scm (udev-service)[requirement]: Add
  'file-system-/dev'.
* gnu/system/file-systems.scm (%devtmpfs-file-system,
  %base-file-systems): New variables.
* gnu/system/install.scm (installation-services)[file-systems]: Use
  %base-file-systems.
* build-aux/hydra/demo-os.scm (file-systems): Likewise.
* doc/guix.texi (System Installation): Show %BASE-FILE-SYSTEMS in the
  example.
  (Using the Configuration System): Likewise.
  (File Systems): Document %base-file-systems, %devtmpfs-file-system,
  %binary-format-file-system, and %fuse-control-file-system.

services: Allow 'check-file-system' to work for non-boot-time file systems.

* gnu/services/base.scm (file-system-service)[start]: Set $PATH so that
  fsck.* can be found.  Reported by "DusXMT".

services: Add 'console-font-service'.

* gnu/services/base.scm (unicode-start, console-font-service): New
  procedures.
  (%base-services): Call 'console-font-service' for TTY1 to TTY6.
* gnu/system/install.scm (installation-services): Add comment about the
  console font.  Call 'console-font-service' for TTY1 to TTY6.

services: syslog: Don't write trivial error messages to /dev/console.

* gnu/services/base.scm (syslog-service): Change "*.err" to "*.alert".

services: Add options to 'guix-service'.

* gnu/services/base.scm (guix-service): Add #:use-substitutes? and
  #:extra-options parameters, and honor them.
* doc/guix.texi (Base Services): Adjust accordingly.

services: Provide a 'loopback' service by default.

* gnu/services/networking.scm (static-networking-service): Add
  #:provision parameter; use it.
* gnu/services/base.scm (%base-services): Call
  'static-networking-service' for "lo".

services: Use more Texinfo markup in docstrings.

* gnu/services/base.scm (host-name-service): Use Texinfo markup.
  (mingetty-service): Comment on #:allow-empty-passwords?.  Improve
  markup.
  (syslog-service, guix-service): Use Texinfo markup.
* gnu/services/networking.scm (static-networking-service): Likewise.
* gnu/services/xorg.scm (slim-service): Likewise.

services: udev: Improve synchronization when starting.

* gnu/services/base.scm (udev-service)[start]: Add 'wait-for-udevd', and
  call it before running 'udevadm trigger'.  Pass --action=add to
  'udevadm trigger'.  Call 'udevadm settle' after 'udevadm trigger'.

services: Update to use the dmd 0.2 API.

* gnu/services/avahi.scm (avahi-service)[start]: Wrap command in a
  list.
* gnu/services/dbus.scm (dbus-service)[start]: Likewise.
* gnu/services/ssh.scm (lsh-service): Likewise.
* gnu/services/base.scm (mingetty-service)[start]: Likewise.
  (nscd-service)[start]: Likewise.
  (syslog-service)[start]: Likewise.
  (guix-service)[start]: Likewise.
  (udev-service)[start]: Use 'exec-command' instead of 'execl'.
* gnu/services/xorg.scm (slim-service)[start]: Likewise, and use
  #:environment-variables.

services: udev: Make sure modules are found, and use "udevadm settle".

* gnu/services/base.scm (udev-service): Set $LINUX_MODULE_DIRECTORY.  In
  the parent, invoke "udevadm settle" before "udevadm trigger".

system: Add a 'system?' field to user accounts.

* gnu/system/shadow.scm (<user-account>)[system?]: New field.
* gnu/system.scm (user-account->gexp): Add it.
* guix/build/activation.scm (add-user): Add #:system? parameter and
  honor it.
  (activate-users+groups): Handle the 'system?' part of user tuples.
  Pass it to 'add-user'.  Don't create PROFILE-DIR when SYSTEM? is
  true.
* gnu/services/dbus.scm (dbus-service): Add 'system?' field for
  "messagebus" account.
* gnu/services/base.scm (guix-build-accounts): Likewise.
* gnu/services/avahi.scm (avahi-service): Likewise.

services: Add udev service, and add it to '%base-services'.

* gnu/services/base.scm (udev-service): New procedure.
  (%base-services): Use it.
* gnu/system.scm (%base-packages): Add UDEV.

system: Remove useless 'members' field of 'user-group'.

* gnu/system/shadow.scm (<user-group>)[members]: Remove field.
* gnu/system/install.scm (installation-os)[users]: Remove 'members'
  fields.  Use 'supplementary-groups' for 'guest'.
* build-aux/hydra/demo-os.scm (users): Likewise.
* gnu/services/base.scm (guix-service): Remove 'members' field.

Merge branch 'master' into core-updates

services: Use a fixed GID for the build group and use that for the store.

This partly reverts commit 185f669 ("services: Make sure the store's
group is the build group.")

* gnu/services/base.scm (guix-service)[activate]: Remove 'chown' call.
  Add 'id' field to 'user-group' form.
* guix/build/install.scm (directives): Set the store's GID to 30000.

services: Make sure the store's group is the build group.

* gnu/services/base.scm (guix-service)[activate]: New variable.  Add
  'chown' call for (%store-prefix).  Set the 'activate' field to
  ACTIVATE.
* guix/build/install.scm (directives): Add comment about STORE's group.