nixpkgs/modules/installer/tools/nixos-option.sh

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#! @shell@ -e
# Allow the location of NixOS sources and the system configuration
# file to be overridden.
: ${mountPoint=/mnt}
: ${NIXOS=/etc/nixos/nixos}
: ${NIXOS_CONFIG=/etc/nixos/configuration.nix}
: ${NIXPKGS=/etc/nixos/nixpkgs}
export NIXOS
usage () {
echo 1>&2 "
Usage: $0 [--install] [-v] [-d] [-l] [--xml] OPTION_NAME
$0 [--install]
This program is used to explore NixOS options by looking at their values or
by looking at their description. It is helpful for understanding how your
configuration is working.
Options:
-i | --install Use the configuration on
${mountPoint:+$mountPoint/}$NIXOS_CONFIG instead of
the current system configuration. Generate a
template configuration if no option name is
specified.
-v | --value Display the current value, based on your
configuration.
-d | --description Display the default value, the example and the
description.
-l | --lookup Display where the option is defined and where it
is declared.
--xml Print an XML representation of the result.
Implies -vdl options.
--help Show this message.
Environment variables affecting $0:
\$mountPoint Path to the target file system.
\$NIXOS Path where the NixOS repository is located.
\$NIXOS_CONFIG Path to your configuration file.
\$NIXPKGS Path to Nix packages.
"
exit 1;
}
#####################
# Process Arguments #
#####################
desc=false
defs=false
value=false
xml=false
install=false
verbose=false
option=""
argfun=""
for arg; do
if test -z "$argfun"; then
case $arg in
-*)
longarg=""
sarg="$arg"
while test "$sarg" != "-"; do
case $sarg in
--*) longarg=$arg; sarg="--";;
-d*) longarg="$longarg --description";;
-v*) longarg="$longarg --value";;
-l*) longarg="$longarg --lookup";;
-i*) longarg="$longarg --install";;
-*) usage;;
esac
# remove the first letter option
sarg="-${sarg#??}"
done
;;
*) longarg=$arg;;
esac
for larg in $longarg; do
case $larg in
--description) desc=true;;
--value) value=true;;
--lookup) defs=true;;
--xml) xml=true;;
--install) install=true;;
--verbose) verbose=true;;
--help) usage;;
-*) usage;;
*) if test -z "$option"; then
option="$larg"
else
usage
fi;;
esac
done
else
case $argfun in
set_*)
var=$(echo $argfun | sed 's,^set_,,')
eval $var=$arg
;;
esac
argfun=""
fi
done
if $xml; then
value=true
desc=true
defs=true
fi
# --install cannot be used with -d -v -l without option name.
if $value || $desc || $defs && $install && test -z "$option"; then
usage
fi
generate=false
if ! $defs && ! $desc && ! $value && $install && test -z "$option"; then
generate=true
fi
if ! $defs && ! $desc; then
value=true
fi
if $verbose; then
set -x
else
set +x
fi
#############################
# Process the configuration #
#############################
evalNix(){
nix-instantiate - --eval-only "$@"
}
evalAttr(){
local prefix=$1
local suffix=$2
local strict=$3
echo "(import $NIXOS {}).$prefix${option:+.$option}${suffix:+.$suffix}" |
evalNix ${strict:+--strict}
}
evalOpt(){
evalAttr "eval.options" "$@"
}
evalCfg(){
evalAttr "config" "$@"
}
findSources(){
local suffix=$1
echo "builtins.map (f: f.source) (import $NIXOS {}).eval.options${option:+.$option}.$suffix" |
evalNix --strict
}
# Given a result from nix-instantiate, recover the list of attributes it
# contains.
attrNames() {
local attributeset=$1
# sed is used to replace un-printable subset by 0s, and to remove most of
# the inner-attribute set, which reduce the likelyhood to encounter badly
# pre-processed input.
echo "builtins.attrNames $attributeset" | \
sed 's,<[A-Z]*>,0,g; :inner; s/{[^\{\}]*};/0;/g; t inner;' | \
evalNix --strict
}
# map a simple list which contains strings or paths.
nixMap() {
local fun="$1"
local list="$2"
local elem
for elem in $list; do
test $elem = '[' -o $elem = ']' && continue;
$fun $elem
done
}
if $install; then
if test -e "$mountPoint$NIXOS"; then
export NIXOS="$mountPoint$NIXOS"
fi
if test -e "$mountPoint$NIXPKGS"; then
export NIXPKGS="$mountPoint$NIXPKGS"
fi
export NIXOS_CONFIG="$mountPoint$NIXOS_CONFIG"
fi
if $generate; then
mkdir -p $(dirname "$NIXOS_CONFIG")
# Scan the hardware and add the result to /etc/nixos/hardware-scan.nix.
hardware_config="${NIXOS_CONFIG%/configuration.nix}/hardware-configuration.nix"
if test -e "$hardware_config"; then
echo "A hardware configuration file exists, generation skipped."
else
echo "Scan your hardware to generate a hardware configuration file."
nixos-hardware-scan > "$hardware_config"
fi
if test -e "$NIXOS_CONFIG"; then
echo 1>&2 "error: Cannot generate a template configuration because a configuration file exists."
exit 1
fi
echo "Generate a template configuration that you should edit."
# Generate a template configuration file where the user has to
# fill the gaps.
echo > "$NIXOS_CONFIG" \
'# Edit this configuration file which defines what would be installed on the
# system. To Help while choosing option value, you can watch at the manual
# page of configuration.nix or at the last chapter of the manual available
# on the virtual console 8 (Alt+F8).
{config, pkgs, ...}:
{
require = [
# Include the configuration for part of your system which have been
# detected automatically.
./hardware-configuration.nix
];
boot.initrd.kernelModules = [
# Specify all kernel modules that are necessary for mounting the root
# file system.
#
# "ext4" "ata_piix"
];
boot.loader.grub = {
# Use grub 2 as boot loader.
enable = true;
version = 2;
# Define on which hard drive you want to install Grub.
# device = "/dev/sda";
};
networking = {
# hostName = "nixos"; # Define your hostname.
interfaceMonitor.enable = true; # Watch for plugged cable.
enableWLAN = true; # Enables Wireless.
};
# Add file system entries for each partition that you want to see mounted
# at boot time. You can add filesystems which are not mounted at boot by
# adding the noauto option.
fileSystems = [
# Mount the root file system
#
# { mountPoint = "/";
# device = "/dev/sda2";
# }
# Copy & Paste & Uncomment & Modify to add any other file system.
#
# { mountPoint = "/data"; # where you want to mount the device
# device = "/dev/sdb"; # the device or the label of the device
# # label = "data";
# fsType = "ext3"; # the type of the partition.
# options = "data=journal";
# }
];
swapDevices = [
# List swap partitions that are mounted at boot time.
#
# { device = "/dev/sda1"; }
];
# Select internationalisation properties.
# i18n = {
# consoleFont = "lat9w-16";
# consoleKeyMap = "us";
# defaultLocale = "en_US.UTF-8";
# };
# List services that you want to enable:
# Add an OpenSSH daemon.
# services.openssh.enable = true;
# Add CUPS to print documents.
# services.printing.enable = true;
# Add XServer (default if you have used a graphical iso)
# services.xserver = {
# enable = true;
# layout = "us";
# xkbOptions = "eurosign:e";
# };
# Add the NixOS Manual on virtual console 8
services.nixosManual.showManual = true;
}
'
exit 0
fi;
# This dupplicate the work made below, but it is useful for processing the
# output of nixos-option with other tools such as nixos-gui.
if $xml; then
evalNix --xml --no-location <<EOF
let
reach = attrs: attrs${option:+.$option};
nixos = import $NIXOS {};
nixpkgs = import $NIXPKGS {};
sources = builtins.map (f: f.source);
opt = reach nixos.eval.options;
cfg = reach nixos.config;
in
with nixpkgs.lib;
let
optStrict = v:
let
traverse = x :
if isAttrs x then
if x ? outPath then true
else all id (mapAttrsFlatten (n: traverseNoAttrs) x)
else traverseNoAttrs x;
traverseNoAttrs = x:
# do not continue in attribute sets
if isAttrs x then true
else if isList x then all id (map traverse x)
else true;
in assert traverse v; v;
in
if isOption opt then
optStrict ({}
// optionalAttrs (opt ? default) { inherit (opt) default; }
// optionalAttrs (opt ? example) { inherit (opt) example; }
// optionalAttrs (opt ? description) { inherit (opt) description; }
// optionalAttrs (opt ? type) { typename = opt.type.name; }
// optionalAttrs (opt ? options) { inherit (opt) options; }
// {
# to disambiguate the xml output.
_isOption = true;
declarations = sources opt.declarations;
definitions = sources opt.definitions;
value = cfg;
})
else
opt
EOF
exit $?
fi
if test "$(evalOpt "_type" 2> /dev/null)" = '"option"'; then
$value && evalCfg;
if $desc; then
$value && echo;
if default=$(evalOpt "default" - 2> /dev/null); then
echo "Default: $default"
else
echo "Default: <None>"
fi
if example=$(evalOpt "example" - 2> /dev/null); then
echo "Example: $example"
fi
echo "Description:"
eval printf $(evalOpt "description")
fi
if $defs; then
$desc || $value && echo;
printPath () { echo " $1"; }
echo "Declared by:"
nixMap printPath "$(findSources "declarations")"
echo ""
echo "Defined by:"
nixMap printPath "$(findSources "definitions")"
echo ""
fi
else
# echo 1>&2 "Warning: This value is not an option."
result=$(evalCfg)
if names=$(attrNames "$result" 2> /dev/null); then
echo 1>&2 "This attribute set contains:"
escapeQuotes () { eval echo "$1"; }
nixMap escapeQuotes "$names"
else
echo 1>&2 "An error occured while looking for attribute names."
echo $result
fi
fi