* gnu/system.scm (<operating-system>)[groups]: Change default to just
the 'root' group.
[sudoers]: New field.
(etc-directory): Add #:sudoers parameter. Add 'sudoers' to the
file union.
(operating-system-etc-directory): Pass #:sudoers to 'etc-directory'.
(%setuid-programs): Add 'sudo'.
(%sudoers-specification): New variable.
* gnu/system/linux.scm (base-pam-services): Add 'sudo'.
* build-aux/hydra/demo-os.scm: Add 'groups' field; add 'guest' to the
'wheel' group.
* gnu/system.scm (<operating-system>)[pam-services, setuid-programs]:
New fields.
(etc-directory)[bashrc]: Prepend /run/setuid-programs to $PATH.
(operating-system-etc-directory): Honor
'operating-system-pam-services'.
(%setuid-programs): New variable.
(operating-system-boot-script): Add (guix build utils) to the set of
imported modules. Call 'activate-setuid-programs' in boot script.
* gnu/system/linux.scm (base-pam-services): New procedure.
* guix/build/activation.scm (%setuid-directory): New variable.
(activate-setuid-programs): New procedure.
* build-aux/hydra/demo-os.scm: Add 'pam-services' field.
* gnu/services.scm (<service>)[inputs]: Remove.
* gnu/system.scm (links): Remove.
(etc-directory): Add PASSWD and SHADOW to #:inputs.
(operating-system-boot-script): Pass ETC to 'dmd-configuration-file'.
(operating-system-derivation): Remove EXTRAS from the union.
* gnu/system/linux.scm (pam-service->configuration): Rewrite in terms of
'gexp->derivation'. Compute the contents on the build side. Expect
'arguments' to contain a list of gexps.
(pam-services->directory): Rewrite in terms of 'gexp->derivation'.
(unix-pam-service): Change 'arguments' to a list of one gexp.
* gnu/system/shadow.scm (<user-account>)[inputs]: Remove.
[shell]: Change default value to a gexp.
(passwd-file): Rewrite in terms of 'gexp->derivation'. Compute
contents on the build side.
* gnu/services/base.scm (host-name-service, mingetty-service,
nscd-service, syslog-service, guix-service): Change 'start' and 'stop'
to gexps; remove 'inputs' field.
(guix-build-accounts): Change 'shell' field to a gexp.
* gnu/services/networking.scm (static-networking-service): Change
'start' and 'stop' to gexps; remove 'inputs' field.
* gnu/services/xorg.scm (slim-service): Likewise.
* gnu/services/dmd.scm (dmd-configuration-file): Expect ETC to be a
derivation. Change 'config' to a gexp. Use 'gexp->file' instead of
'text-file'.
* doc/guix.texi (Defining Services): Update nscd example with gexps, and
without 'inputs'. Add xref to "G-Expressions".
* gnu/system/vm.scm (system-qemu-image): Build a 'motd' and an 'issue'
file. Pass 'unix-pam-service' that motd. Have /etc/issue point to
the 'issue' file.
