165 lines
3.6 KiB
Bash
165 lines
3.6 KiB
Bash
#! @shell@ -e
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# Allow the location of NixOS sources and the system configuration
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# file to be overridden.
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: ${NIXOS_PATH=/etc/nixos/nixos}
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: ${NIXOS=/etc/nixos/nixos}
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: ${NIXPKGS=/etc/nixos/nixpkgs}
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: ${NIXOS_CONFIG=/etc/nixos/configuration.nix}
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export NIXOS_PATH
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usage () {
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echo 1>&2 "
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Usage: $0 OPTION_NAME [-v] [-d] [-l]
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This program is used to explore NixOS options by looking at their values or
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by looking at their description. It is helpful for understanding the how
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your configuration is working.
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Options:
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-v | --value Display the current value, based on your
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configuration.
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-d | --default Display the default value, the example and the
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description.
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-l | --lookup Display where the option is defined and where it
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is declared.
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--help Show this message.
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Environment variables affecting nixos-option:
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\$NIXOS_PATH Path where the NixOS repository is located.
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\$NIXOS_CONFIG Path to your configuration file.
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\$NIXPKGS Path to Nix packages.
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"
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exit 1;
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}
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#####################
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# Process Arguments #
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#####################
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desc=false
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defs=false
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value=false
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verbose=false
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option=""
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argfun=""
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for arg; do
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if test -z "$argfun"; then
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case $arg in
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-d|--description) desc=true;;
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-v|--value) value=true;;
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-l|--lookup) defs=true;;
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--verbose) verbose=true;;
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--help) usage;;
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-*) usage;;
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*) if test -z "$option"; then
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option="$arg"
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else
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usage
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fi;;
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esac
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else
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case $argfun in
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set_*)
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var=$(echo $argfun | sed 's,^set_,,')
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eval $var=$arg
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;;
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esac
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argfun=""
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fi
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done
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if ! $defs && ! $desc; then
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value=true
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fi
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if $verbose; then
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set -x
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else
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set +x
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fi
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#############################
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# Process the configuration #
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#############################
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evalAttr(){
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local prefix=$1
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local suffix=$2
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local strict=$3
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echo "(import $NIXOS_PATH {}).$prefix${option:+.$option}${suffix:+.$suffix}" |
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nix-instantiate - --eval-only ${strict:+--strict}
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}
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evalOpt(){
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evalAttr "eval.options" "$@"
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}
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evalCfg(){
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evalAttr "config" "$@"
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}
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findSources(){
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local suffix=$1
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echo "builtins.map (f: f.source) (import $NIXOS_PATH {}).eval.options${option:+.$option}.$suffix" |
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nix-instantiate - --eval-only --strict
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}
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if test "$(evalOpt "_type" 2> /dev/null)" = '"option"'; then
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$value && evalCfg;
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if $desc; then
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$value && echo;
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if default=$(evalOpt "default" - 2> /dev/null); then
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echo "Default: $default"
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else
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echo "Default: <None>"
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fi
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if example=$(evalOpt "example" - 2> /dev/null); then
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echo "Example: $example"
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fi
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echo "Description:"
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eval printf $(evalOpt "description")
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fi
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if $defs; then
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$desc || $value && echo;
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echo "Declared by:"
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for f in $(findSources "declarations"); do
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test $f = '[' -o $f = ']' && continue;
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echo " $f"
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done
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echo ""
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echo "Defined by:"
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for f in $(findSources "definitions"); do
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test $f = '[' -o $f = ']' && continue;
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echo " $f"
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done
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echo ""
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fi
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else
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# echo 1>&2 "Warning: This value is not an option."
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result=$(evalCfg)
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if names=$(echo "builtins.attrNames $result" | sed 's,<CODE>,"<CODE>",g' | nix-instantiate - --eval-only --strict 2> /dev/null); then
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echo 1>&2 "This attribute set contains:"
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for attr in $names; do
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test $attr = '[' -o $attr = ']' && continue;
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eval echo $attr # escape extra double-quotes in the attribute name.
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done
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else
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echo $result
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fi
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fi
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