diff options
Diffstat (limited to 'nixos/doc/manual/configuration/config-file.xml')
| -rw-r--r-- | nixos/doc/manual/configuration/config-file.xml | 71 |
1 files changed, 14 insertions, 57 deletions
diff --git a/nixos/doc/manual/configuration/config-file.xml b/nixos/doc/manual/configuration/config-file.xml index eadafb94b8f6..38296caaa9a4 100644 --- a/nixos/doc/manual/configuration/config-file.xml +++ b/nixos/doc/manual/configuration/config-file.xml @@ -13,15 +13,7 @@ { <replaceable>option definitions</replaceable> } </programlisting> - The first line (<literal>{ config, pkgs, ... }:</literal>) denotes that this - is actually a function that takes at least the two arguments - <varname>config</varname> and <varname>pkgs</varname>. (These are explained - later.) The function returns a <emphasis>set</emphasis> of option definitions - (<literal>{ <replaceable>...</replaceable> }</literal>). These definitions - have the form <literal><replaceable>name</replaceable> = - <replaceable>value</replaceable></literal>, where - <replaceable>name</replaceable> is the name of an option and - <replaceable>value</replaceable> is its value. For example, + The first line (<literal>{ config, pkgs, ... }:</literal>) denotes that this is actually a function that takes at least the two arguments <varname>config</varname> and <varname>pkgs</varname>. (These are explained later.) The function returns a <emphasis>set</emphasis> of option definitions (<literal>{ <replaceable>...</replaceable> }</literal>). These definitions have the form <literal><replaceable>name</replaceable> = <replaceable>value</replaceable></literal>, where <replaceable>name</replaceable> is the name of an option and <replaceable>value</replaceable> is its value. For example, <programlisting> { config, pkgs, ... }: @@ -30,19 +22,11 @@ <xref linkend="opt-services.httpd.documentRoot"/> = "/webroot"; } </programlisting> - defines a configuration with three option definitions that together enable - the Apache HTTP Server with <filename>/webroot</filename> as the document - root. + defines a configuration with three option definitions that together enable the Apache HTTP Server with <filename>/webroot</filename> as the document root. </para> <para> - Sets can be nested, and in fact dots in option names are shorthand for - defining a set containing another set. For instance, - <xref linkend="opt-services.httpd.enable"/> defines a set named - <varname>services</varname> that contains a set named - <varname>httpd</varname>, which in turn contains an option definition named - <varname>enable</varname> with value <literal>true</literal>. This means that - the example above can also be written as: + Sets can be nested, and in fact dots in option names are shorthand for defining a set containing another set. For instance, <xref linkend="opt-services.httpd.enable"/> defines a set named <varname>services</varname> that contains a set named <varname>httpd</varname>, which in turn contains an option definition named <varname>enable</varname> with value <literal>true</literal>. This means that the example above can also be written as: <programlisting> { config, pkgs, ... }: @@ -55,22 +39,15 @@ }; } </programlisting> - which may be more convenient if you have lots of option definitions that - share the same prefix (such as <literal>services.httpd</literal>). + which may be more convenient if you have lots of option definitions that share the same prefix (such as <literal>services.httpd</literal>). </para> <para> - NixOS checks your option definitions for correctness. For instance, if you - try to define an option that doesn’t exist (that is, doesn’t have a - corresponding <emphasis>option declaration</emphasis>), - <command>nixos-rebuild</command> will give an error like: + NixOS checks your option definitions for correctness. For instance, if you try to define an option that doesn’t exist (that is, doesn’t have a corresponding <emphasis>option declaration</emphasis>), <command>nixos-rebuild</command> will give an error like: <screen> The option `services.httpd.enable' defined in `/etc/nixos/configuration.nix' does not exist. </screen> - Likewise, values in option definitions must have a correct type. For - instance, <option>services.httpd.enable</option> must be a Boolean - (<literal>true</literal> or <literal>false</literal>). Trying to give it a - value of another type, such as a string, will cause an error: + Likewise, values in option definitions must have a correct type. For instance, <option>services.httpd.enable</option> must be a Boolean (<literal>true</literal> or <literal>false</literal>). Trying to give it a value of another type, such as a string, will cause an error: <screen> The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is not a boolean. </screen> @@ -89,12 +66,10 @@ The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is no <programlisting> <xref linkend="opt-networking.hostName"/> = "dexter"; </programlisting> - Special characters can be escaped by prefixing them with a backslash - (e.g. <literal>\"</literal>). + Special characters can be escaped by prefixing them with a backslash (e.g. <literal>\"</literal>). </para> <para> - Multi-line strings can be enclosed in <emphasis>double single - quotes</emphasis>, e.g. + Multi-line strings can be enclosed in <emphasis>double single quotes</emphasis>, e.g. <programlisting> <xref linkend="opt-networking.extraHosts"/> = '' @@ -102,13 +77,7 @@ The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is no 10.0.0.1 server ''; </programlisting> - The main difference is that it strips from each line a number of spaces - equal to the minimal indentation of the string as a whole (disregarding - the indentation of empty lines), and that characters like - <literal>"</literal> and <literal>\</literal> are not special (making it - more convenient for including things like shell code). See more info - about this in the Nix manual - <link + The main difference is that it strips from each line a number of spaces equal to the minimal indentation of the string as a whole (disregarding the indentation of empty lines), and that characters like <literal>"</literal> and <literal>\</literal> are not special (making it more convenient for including things like shell code). See more info about this in the Nix manual <link xlink:href="https://nixos.org/nix/manual/#ssec-values">here</link>. </para> </listitem> @@ -137,12 +106,7 @@ The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is no <programlisting> <xref linkend="opt-boot.kernel.sysctl"/>."net.ipv4.tcp_keepalive_time" = 60; </programlisting> - (Note that here the attribute name - <literal>net.ipv4.tcp_keepalive_time</literal> is enclosed in quotes to - prevent it from being interpreted as a set named <literal>net</literal> - containing a set named <literal>ipv4</literal>, and so on. This is - because it’s not a NixOS option but the literal name of a Linux kernel - setting.) + (Note that here the attribute name <literal>net.ipv4.tcp_keepalive_time</literal> is enclosed in quotes to prevent it from being interpreted as a set named <literal>net</literal> containing a set named <literal>ipv4</literal>, and so on. This is because it’s not a NixOS option but the literal name of a Linux kernel setting.) </para> </listitem> </varlistentry> @@ -152,8 +116,7 @@ The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is no </term> <listitem> <para> - Sets were introduced above. They are name/value pairs enclosed in braces, - as in the option definition + Sets were introduced above. They are name/value pairs enclosed in braces, as in the option definition <programlisting> <xref linkend="opt-fileSystems"/>."/boot" = { device = "/dev/sda1"; @@ -170,8 +133,7 @@ The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is no </term> <listitem> <para> - The important thing to note about lists is that list elements are - separated by whitespace, like this: + The important thing to note about lists is that list elements are separated by whitespace, like this: <programlisting> <xref linkend="opt-boot.kernelModules"/> = [ "fuse" "kvm-intel" "coretemp" ]; </programlisting> @@ -188,9 +150,7 @@ swapDevices = [ { device = "/dev/disk/by-label/swap"; } ]; </term> <listitem> <para> - Usually, the packages you need are already part of the Nix Packages - collection, which is a set that can be accessed through the function - argument <varname>pkgs</varname>. Typical uses: + Usually, the packages you need are already part of the Nix Packages collection, which is a set that can be accessed through the function argument <varname>pkgs</varname>. Typical uses: <programlisting> <xref linkend="opt-environment.systemPackages"/> = [ pkgs.thunderbird @@ -199,10 +159,7 @@ swapDevices = [ { device = "/dev/disk/by-label/swap"; } ]; <xref linkend="opt-services.postgresql.package"/> = pkgs.postgresql_10; </programlisting> - The latter option definition changes the default PostgreSQL package used - by NixOS’s PostgreSQL service to 10.x. For more information on - packages, including how to add new ones, see - <xref linkend="sec-custom-packages"/>. + The latter option definition changes the default PostgreSQL package used by NixOS’s PostgreSQL service to 10.x. For more information on packages, including how to add new ones, see <xref linkend="sec-custom-packages"/>. </para> </listitem> </varlistentry> |