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Diffstat (limited to 'doc/guix.texi')
| -rw-r--r-- | doc/guix.texi | 626 |
1 files changed, 602 insertions, 24 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 043aad1b65..94d7a29bdf 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -30,7 +30,7 @@ Copyright @copyright{} 2016 Ben Woodcroft@* Copyright @copyright{} 2016, 2017, 2018 Chris Marusich@* Copyright @copyright{} 2016, 2017, 2018 Efraim Flashner@* Copyright @copyright{} 2016 John Darrington@* -Copyright @copyright{} 2016, 2017 Nils Gillmann@* +Copyright @copyright{} 2016, 2017 ng0@* Copyright @copyright{} 2016, 2017, 2018, 2019 Jan Nieuwenhuizen@* Copyright @copyright{} 2016 Julien Lepiller@* Copyright @copyright{} 2016 Alex ter Weele@* @@ -48,7 +48,7 @@ Copyright @copyright{} 2017 Maxim Cournoyer@* Copyright @copyright{} 2017, 2018 Tobias Geerinckx-Rice@* Copyright @copyright{} 2017 George Clemmer@* Copyright @copyright{} 2017 Andy Wingo@* -Copyright @copyright{} 2017, 2018 Arun Isaac@* +Copyright @copyright{} 2017, 2018, 2019 Arun Isaac@* Copyright @copyright{} 2017 nee@* Copyright @copyright{} 2018 Rutger Helling@* Copyright @copyright{} 2018 Oleg Pykhalov@* @@ -4760,14 +4760,24 @@ symlinks, as well as empty mount points for virtual file systems like procfs. @end table +@cindex relocatable binaries @item --relocatable @itemx -R Produce @dfn{relocatable binaries}---i.e., binaries that can be placed -anywhere in the file system hierarchy and run from there. For example, -if you create a pack containing Bash with: +anywhere in the file system hierarchy and run from there. + +When this option is passed once, the resulting binaries require support for +@dfn{user namespaces} in the kernel Linux; when passed +@emph{twice}@footnote{Here's a trick to memorize it: @code{-RR}, which adds +PRoot support, can be thought of as the abbreviation of ``Really +Relocatable''. Neat, isn't it?}, relocatable binaries fall to back to PRoot +if user namespaces are unavailable, and essentially work anywhere---see below +for the implications. + +For example, if you create a pack containing Bash with: @example -guix pack -R -S /mybin=bin bash +guix pack -RR -S /mybin=bin bash @end example @noindent @@ -4786,12 +4796,23 @@ In that shell, if you type @code{ls /gnu/store}, you'll notice that altogether! That is probably the simplest way to deploy Guix-built software on a non-Guix machine. -There's a gotcha though: this technique relies on the @dfn{user -namespace} feature of the kernel Linux, which allows unprivileged users -to mount or change root. Old versions of Linux did not support it, and -some GNU/Linux distributions turn it off; on these systems, programs -from the pack @emph{will fail to run}, unless they are unpacked in the -root file system. +@quotation Note +By default, relocatable binaries rely on the @dfn{user namespace} feature of +the kernel Linux, which allows unprivileged users to mount or change root. +Old versions of Linux did not support it, and some GNU/Linux distributions +turn it off. + +To produce relocatable binaries that work even in the absence of user +namespaces, pass @option{--relocatable} or @option{-R} @emph{twice}. In that +case, binaries will try user namespace support and fall back to PRoot if user +namespaces are not supported. + +The @uref{https://proot-me.github.io/, PRoot} program provides the necessary +support for file system virtualization. It achieves that by using the +@code{ptrace} system call on the running program. This approach has the +advantage to work without requiring special kernel support, but it incurs +run-time overhead every time a system call is made. +@end quotation @item --expression=@var{expr} @itemx -e @var{expr} @@ -5220,6 +5241,29 @@ with @var{libressl}. Then we use it to define a @dfn{variant} of the This is exactly what the @option{--with-input} command-line option does (@pxref{Package Transformation Options, @option{--with-input}}). +The following variant of @code{package-input-rewriting} can match packages to +be replaced by name rather than by identity. + +@deffn {Scheme Procedure} package-input-rewriting/spec @var{replacements} +Return a procedure that, given a package, applies the given @var{replacements} to +all the package graph (excluding implicit inputs). @var{replacements} is a list of +spec/procedures pair; each spec is a package specification such as @code{"gcc"} or +@code{"guile@@2"}, and each procedure takes a matching package and returns a +replacement for that package. +@end deffn + +The example above could be rewritten this way: + +@example +(define libressl-instead-of-openssl + ;; Replace all the packages called "openssl" with LibreSSL. + (package-input-rewriting/spec `(("openssl" . ,(const libressl))))) +@end example + +The key difference here is that, this time, packages are matched by spec and +not by identity. In other words, any package in the graph that is called +@code{openssl} will be replaced. + A more generic procedure to rewrite a package dependency graph is @code{package-mapping}: it supports arbitrary changes to nodes in the graph. @@ -5791,8 +5835,8 @@ some cases, you will need to unpack the package's source code to a different directory structure than the one indicated by the import path, and @code{#:unpack-path} should be used in such cases. -Packages that provide Go libraries should be installed along with their -source code. The key @code{#:install-source?}, which defaults to +Packages that provide Go libraries should install their source code into +the built output. The key @code{#:install-source?}, which defaults to @code{#t}, controls whether or not the source code is installed. It can be set to @code{#f} for packages that only provide executable files. @end defvr @@ -7759,24 +7803,24 @@ must be compatible. If @var{replacement} is somehow incompatible with @var{package}, then the resulting package may be unusable. Use with care! -@item --with-branch=@var{package}=@var{branch} +@item --with-git-url=@var{package}=@var{url} @cindex Git, using the latest commit @cindex latest commit, building -Build @var{package} from the latest commit of @var{branch}. The @code{source} -field of @var{package} must be an origin with the @code{git-fetch} method -(@pxref{origin Reference}) or a @code{git-checkout} object; the repository URL -is taken from that @code{source}. Git sub-modules of the repository are -fetched, recursively. +Build @var{package} from the latest commit of the @code{master} branch of the +Git repository at @var{url}. Git sub-modules of the repository are fetched, +recursively. -For instance, the following command builds @code{guile-sqlite3} from the -latest commit of its @code{master} branch, and then builds @code{guix} (which -depends on it) and @code{cuirass} (which depends on @code{guix}) against this -specific @code{guile-sqlite3} build: +For example, the following command builds the NumPy Python library against the +latest commit of the master branch of Python itself: @example -guix build --with-branch=guile-sqlite3=master cuirass +guix build python-numpy \ + --with-git-url=python=https://github.com/python/cpython @end example +This option can also be combined with @code{--with-branch} or +@code{--with-commit} (see below). + @cindex continuous integration Obviously, since it uses the latest commit of the given branch, the result of such a command varies over time. Nevertheless it is a convenient way to @@ -7788,6 +7832,22 @@ Checkouts are kept in a cache under @file{~/.cache/guix/checkouts} to speed up consecutive accesses to the same repository. You may want to clean it up once in a while to save disk space. +@item --with-branch=@var{package}=@var{branch} +Build @var{package} from the latest commit of @var{branch}. If the +@code{source} field of @var{package} is an origin with the @code{git-fetch} +method (@pxref{origin Reference}) or a @code{git-checkout} object, the +repository URL is taken from that @code{source}. Otherwise you have to use +@code{--with-git-url} to specify the URL of the Git repository. + +For instance, the following command builds @code{guile-sqlite3} from the +latest commit of its @code{master} branch, and then builds @code{guix} (which +depends on it) and @code{cuirass} (which depends on @code{guix}) against this +specific @code{guile-sqlite3} build: + +@example +guix build --with-branch=guile-sqlite3=master cuirass +@end example + @item --with-commit=@var{package}=@var{commit} This is similar to @code{--with-branch}, except that it builds from @var{commit} rather than the tip of a branch. @var{commit} must be a valid @@ -8781,6 +8841,8 @@ the updater for @uref{https://hackage.haskell.org, Hackage} packages. the updater for @uref{https://www.stackage.org, Stackage} packages. @item crate the updater for @uref{https://crates.io, Crates} packages. +@item launchpad +the updater for @uref{https://launchpad.net, Launchpad} packages. @end table For instance, the following command only checks for updates of Emacs @@ -11077,6 +11139,7 @@ declaration. * Telephony Services:: Telephony services. * Monitoring Services:: Monitoring services. * Kerberos Services:: Kerberos services. +* LDAP Services:: LDAP services. * Web Services:: Web servers. * Certificate Services:: TLS certificates via Let's Encrypt. * DNS Services:: DNS daemons. @@ -17623,6 +17686,484 @@ Local accounts with lower values will silently fail to authenticate. @end deftp +@node LDAP Services +@subsection LDAP Services +@cindex LDAP +@cindex nslcd, LDAP service + +The @code{(gnu services authentication)} module provides the +@code{nslcd-service-type}, which can be used to authenticate against an LDAP +server. In addition to configuring the service itself, you may want to add +@code{ldap} as a name service to the Name Service Switch. @xref{Name Service +Switch} for detailed information. + +Here is a simple operating system declaration with a default configuration of +the @code{nslcd-service-type} and a Name Service Switch configuration that +consults the @code{ldap} name service last: + +@example +(use-service-modules authentication) +(use-modules (gnu system nss)) +... +(operating-system + ... + (services + (cons* + (service nslcd-service-type) + (service dhcp-client-service-type) + %base-services)) + (name-service-switch + (let ((services (list (name-service (name "db")) + (name-service (name "files")) + (name-service (name "ldap"))))) + (name-service-switch + (inherit %mdns-host-lookup-nss) + (password services) + (shadow services) + (group services) + (netgroup services) + (gshadow services))))) +@end example + +@c %start of generated documentation for nslcd-configuration + +Available @code{nslcd-configuration} fields are: + +@deftypevr {@code{nslcd-configuration} parameter} package nss-pam-ldapd +The @code{nss-pam-ldapd} package to use. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number threads +The number of threads to start that can handle requests and perform LDAP +queries. Each thread opens a separate connection to the LDAP server. +The default is to start 5 threads. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} string uid +This specifies the user id with which the daemon should be run. + +Defaults to @samp{"nslcd"}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} string gid +This specifies the group id with which the daemon should be run. + +Defaults to @samp{"nslcd"}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} log-option log +This option controls the way logging is done via a list containing +SCHEME and LEVEL. The SCHEME argument may either be the symbols "none" +or "syslog", or an absolute file name. The LEVEL argument is optional +and specifies the log level. The log level may be one of the following +symbols: "crit", "error", "warning", "notice", "info" or "debug". All +messages with the specified log level or higher are logged. + +Defaults to @samp{("/var/log/nslcd" info)}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} list uri +The list of LDAP server URIs. Normally, only the first server will be +used with the following servers as fall-back. + +Defaults to @samp{("ldap://localhost:389/")}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string ldap-version +The version of the LDAP protocol to use. The default is to use the +maximum version supported by the LDAP library. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string binddn +Specifies the distinguished name with which to bind to the directory +server for lookups. The default is to bind anonymously. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string bindpw +Specifies the credentials with which to bind. This option is only +applicable when used with binddn. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string rootpwmoddn +Specifies the distinguished name to use when the root user tries to +modify a user's password using the PAM module. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string rootpwmodpw +Specifies the credentials with which to bind if the root user tries to +change a user's password. This option is only applicable when used with +rootpwmoddn + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-mech +Specifies the SASL mechanism to be used when performing SASL +authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-realm +Specifies the SASL realm to be used when performing SASL authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-authcid +Specifies the authentication identity to be used when performing SASL +authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-authzid +Specifies the authorization identity to be used when performing SASL +authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean sasl-canonicalize? +Determines whether the LDAP server host name should be canonicalised. If +this is enabled the LDAP library will do a reverse host name lookup. By +default, it is left up to the LDAP library whether this check is +performed or not. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string krb5-ccname +Set the name for the GSS-API Kerberos credentials cache. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} string base +The directory search base. + +Defaults to @samp{"dc=example,dc=com"}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} scope-option scope +Specifies the search scope (subtree, onelevel, base or children). The +default scope is subtree; base scope is almost never useful for name +service lookups; children scope is not supported on all servers. + +Defaults to @samp{(subtree)}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-deref-option deref +Specifies the policy for dereferencing aliases. The default policy is +to never dereference aliases. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean referrals +Specifies whether automatic referral chasing should be enabled. The +default behaviour is to chase referrals. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} list-of-map-entries maps +This option allows for custom attributes to be looked up instead of the +default RFC 2307 attributes. It is a list of maps, each consisting of +the name of a map, the RFC 2307 attribute to match and the query +expression for the attribute as it is available in the directory. + +Defaults to @samp{()}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} list-of-filter-entries filters +A list of filters consisting of the name of a map to which the filter +applies and an LDAP search filter expression. + +Defaults to @samp{()}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number bind-timelimit +Specifies the time limit in seconds to use when connecting to the +directory server. The default value is 10 seconds. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number timelimit +Specifies the time limit (in seconds) to wait for a response from the +LDAP server. A value of zero, which is the default, is to wait +indefinitely for searches to be completed. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number idle-timelimit +Specifies the period if inactivity (in seconds) after which the con‐ +nection to the LDAP server will be closed. The default is not to time +out connections. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number reconnect-sleeptime +Specifies the number of seconds to sleep when connecting to all LDAP +servers fails. By default one second is waited between the first +failure and the first retry. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number reconnect-retrytime +Specifies the time after which the LDAP server is considered to be +permanently unavailable. Once this time is reached retries will be done +only once per this time period. The default value is 10 seconds. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-ssl-option ssl +Specifies whether to use SSL/TLS or not (the default is not to). If +'start-tls is specified then StartTLS is used rather than raw LDAP over +SSL. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-tls-reqcert-option tls-reqcert +Specifies what checks to perform on a server-supplied certificate. The +meaning of the values is described in the ldap.conf(5) manual page. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cacertdir +Specifies the directory containing X.509 certificates for peer authen‐ +tication. This parameter is ignored when using GnuTLS. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cacertfile +Specifies the path to the X.509 certificate for peer authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-randfile +Specifies the path to an entropy source. This parameter is ignored when +using GnuTLS. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-ciphers +Specifies the ciphers to use for TLS as a string. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cert +Specifies the path to the file containing the local certificate for +client TLS authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-key +Specifies the path to the file containing the private key for client TLS +authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number pagesize +Set this to a number greater than 0 to request paged results from the +LDAP server in accordance with RFC2696. The default (0) is to not +request paged results. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-ignore-users-option nss-initgroups-ignoreusers +This option prevents group membership lookups through LDAP for the +specified users. Alternatively, the value 'all-local may be used. With +that value nslcd builds a full list of non-LDAP users on startup. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-min-uid +This option ensures that LDAP users with a numeric user id lower than +the specified value are ignored. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-uid-offset +This option specifies an offset that is added to all LDAP numeric user +ids. This can be used to avoid user id collisions with local users. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-gid-offset +This option specifies an offset that is added to all LDAP numeric group +ids. This can be used to avoid user id collisions with local groups. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-nested-groups +If this option is set, the member attribute of a group may point to +another group. Members of nested groups are also returned in the higher +level group and parent groups are returned when finding groups for a +specific user. The default is not to perform extra searches for nested +groups. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-getgrent-skipmembers +If this option is set, the group member list is not retrieved when +looking up groups. Lookups for finding which groups a user belongs to +will remain functional so the user will likely still get the correct +groups assigned on login. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-disable-enumeration +If this option is set, functions which cause all user/group entries to +be loaded from the directory will not succeed in doing so. This can +dramatically reduce LDAP server load in situations where there are a +great number of users and/or groups. This option is not recommended for +most configurations. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string validnames +This option can be used to specify how user and group names are verified +within the system. This pattern is used to check all user and group +names that are requested and returned from LDAP. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean ignorecase +This specifies whether or not to perform searches using case-insensitive +matching. Enabling this could open up the system to authorization +bypass vulnerabilities and introduce nscd cache poisoning +vulnerabilities which allow denial of service. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-boolean pam-authc-ppolicy +This option specifies whether password policy controls are requested and +handled from the LDAP server when performing user authentication. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-authc-search +By default nslcd performs an LDAP search with the user's credentials +after BIND (authentication) to ensure that the BIND operation was +successful. The default search is a simple check to see if the user's +DN exists. A search filter can be specified that will be used instead. +It should return at least one entry. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-authz-search +This option allows flexible fine tuning of the authorisation check that +should be performed. The search filter specified is executed and if any +entries match, access is granted, otherwise access is denied. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-password-prohibit-message +If this option is set password modification using pam_ldap will be +denied and the specified message will be presented to the user instead. +The message can be used to direct the user to an alternative means of +changing their password. + +Defaults to @samp{disabled}. + +@end deftypevr + +@deftypevr {@code{nslcd-configuration} parameter} list pam-services +List of pam service names for which LDAP authentication should suffice. + +Defaults to @samp{()}. + +@end deftypevr + +@c %end of generated documentation for nslcd-configuration + + @node Web Services @subsection Web Services @@ -20303,6 +20844,15 @@ The directory to scan for music files. @item @code{playlist-dir} (default: @code{"~/.mpd/playlists"}) The directory to store playlists. +@item @code{db-file} (default: @code{"~/.mpd/tag_cache"}) +The location of the music database. + +@item @code{state-file} (default: @code{"~/.mpd/state"}) +The location of the file that stores current MPD's state. + +@item @code{sticker-file} (default: @code{"~/.mpd/sticker.sql"}) +The location of the sticker database. + @item @code{port} (default: @code{"6600"}) The port to run mpd on. @@ -22434,6 +22984,34 @@ that enables sharing the clipboard with a vm and setting the guest display resolution when the graphical console window resizes. @end deffn +@cindex inputattach +@subsubheading inputattach Service + +@cindex tablet input, for Xorg +@cindex touchscreen input, for Xorg +The @uref{https://linuxwacom.github.io/, inputattach} service allows you to +use input devices such as Wacom tablets, touchscreens, or joysticks with the +Xorg display server. + +@deffn {Scheme Variable} inputattach-service-type +Type of a service that runs @command{inputattach} on a device and +dispatches events from it. +@end deffn + +@deftp {Data Type} inputattach-configuration +@table @asis +@item @code{device-type} (default: @code{"wacom"}) +The type of device to connect to. Run @command{inputattach --help}, from the +@code{inputattach} package, to see the list of supported device types. + +@item @code{device} (default: @code{"/dev/ttyS0"}) +The device file to connect to the device. + +@item @code{log-file} (default: @code{#f}) +If true, this must be the name of a file to log messages to. +@end table +@end deftp + @subsection Dictionary Services @cindex dictionary The @code{(gnu services dict)} module provides the following service: |