Warning
This program is experimental and its interface is subject to change.
Name
nix repl - start an interactive environment for evaluating Nix expressions
Synopsis
nix repl [option...] installables...
Examples
-
Display all special commands within the REPL:
# nix repl nix-repl> :? -
Evaluate some simple Nix expressions:
# nix repl nix-repl> 1 + 2 3 nix-repl> map (x: x * 2) [1 2 3] [ 2 4 6 ] -
Interact with Nixpkgs in the REPL:
# nix repl --file example.nix Loading Installable ''... Added 3 variables. # nix repl --expr '{a={b=3;c=4;};}' Loading Installable ''... Added 1 variables. # nix repl --expr '{a={b=3;c=4;};}' a Loading Installable ''... Added 1 variables. # nix repl --extra-experimental-features 'flakes repl-flake' nixpkgs Loading Installable 'flake:nixpkgs#'... Added 5 variables. nix-repl> legacyPackages.x86_64-linux.emacs.name "emacs-27.1" nix-repl> legacyPackages.x86_64-linux.emacs.name "emacs-27.1" nix-repl> :q # nix repl --expr 'import <nixpkgs>{}' Loading Installable ''... Added 12439 variables. nix-repl> emacs.name "emacs-27.1" nix-repl> emacs.drvPath "/nix/store/lp0sjrhgg03y2n0l10n70rg0k7hhyz0l-emacs-27.1.drv" nix-repl> drv = runCommand "hello" { buildInputs = [ hello ]; } "hello; hello > $out" nix-repl> :b drv this derivation produced the following outputs: out -> /nix/store/0njwbgwmkwls0w5dv9mpc1pq5fj39q0l-hello nix-repl> builtins.readFile drv "Hello, world!\n" nix-repl> :log drv Hello, world!
Description
This command provides an interactive environment for evaluating Nix expressions. (REPL stands for 'read–eval–print loop'.)
On startup, it loads the Nix expressions named files and adds them
into the lexical scope. You can load addition files using the :l <filename> command, or reload all files using :r.
Options
--stdinRead installables from the standard input. No default installable applied.
Common evaluation options:
-
--argname expr Pass the value expr as the argument name to Nix functions. -
--argstrname string Pass the string string as the argument name to Nix functions. -
--debuggerStart an interactive environment if evaluation fails. -
--eval-storestore-url The URL of the Nix store to use for evaluation, i.e. to store derivations (.drvfiles) and inputs referenced by them. -
--impureAllow access to mutable paths and repositories. -
--include/-Ipath Add path to the Nix search path. The Nix search path is initialized from the colon-separatedNIX_PATHenvironment variable, and is used to look up the location of Nix expressions using paths enclosed in angle brackets (i.e.,<nixpkgs>).For instance, passing
-I /home/eelco/Dev -I /etc/nixoswill cause Nix to look for paths relative to
/home/eelco/Devand/etc/nixos, in that order. This is equivalent to setting theNIX_PATHenvironment variable to/home/eelco/Dev:/etc/nixosIt is also possible to match paths against a prefix. For example, passing
-I nixpkgs=/home/eelco/Dev/nixpkgs-branch -I /etc/nixoswill cause Nix to search for
<nixpkgs/path>in/home/eelco/Dev/nixpkgs-branch/pathand/etc/nixos/nixpkgs/path.If a path in the Nix search path starts with
http://orhttps://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must consist of a single top-level directory. For example, passing-I nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gztells Nix to download and use the current contents of the
masterbranch in thenixpkgsrepository.The URLs of the tarballs from the official
nixos.orgchannels (see the manual page fornix-channel) can be abbreviated aschannel:<channel-name>. For instance, the following two flags are equivalent:-I nixpkgs=channel:nixos-21.05 -I nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xzYou can also fetch source trees using flake URLs and add them to the search path. For instance,
-I nixpkgs=flake:nixpkgsspecifies that the prefix
nixpkgsshall refer to the source tree downloaded from thenixpkgsentry in the flake registry. Similarly,-I nixpkgs=flake:github:NixOS/nixpkgs/nixos-22.05makes
<nixpkgs>refer to a particular branch of theNixOS/nixpkgsrepository on GitHub. -
--override-flakeoriginal-ref resolved-ref Override the flake registries, redirecting original-ref to resolved-ref.
Common flake-related options:
-
--commit-lock-fileCommit changes to the flake's lock file. -
--inputs-fromflake-url Use the inputs of the specified flake as registry entries. -
--no-registriesDon't allow lookups in the flake registries. This option is deprecated; use--no-use-registries. -
--no-update-lock-fileDo not allow any updates to the flake's lock file. -
--no-write-lock-fileDo not write the flake's newly generated lock file. -
--output-lock-fileflake-lock-path Write the given lock file instead offlake.lockwithin the top-level flake. -
--override-inputinput-path flake-url Override a specific flake input (e.g.dwarffs/nixpkgs). This implies--no-write-lock-file. -
--recreate-lock-fileRecreate the flake's lock file from scratch. -
--reference-lock-fileflake-lock-path Read the given lock file instead offlake.lockwithin the top-level flake. -
--update-inputinput-path Update a specific flake input (ignoring its previous entry in the lock file).
Logging-related options:
-
--debugSet the logging verbosity level to 'debug'. -
--log-formatformat Set the format of log output; one ofraw,internal-json,barorbar-with-logs. -
--print-build-logs/-LPrint full build logs on standard error. -
--quietDecrease the logging verbosity level. -
--verbose/-vIncrease the logging verbosity level.
Miscellaneous global options:
-
--helpShow usage information. -
--offlineDisable substituters and consider all previously downloaded files up-to-date. -
--optionname value Set the Nix configuration setting name to value (overridingnix.conf). -
--refreshConsider all previously downloaded files out-of-date. -
--repairDuring evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths. -
--versionShow version information.
Options that change the interpretation of installables:
-
--exprexpr Interpret installables as attribute paths relative to the Nix expression expr. -
--file/-ffile Interpret installables as attribute paths relative to the Nix expression stored in file. If file is the character -, then a Nix expression will be read from standard input. Implies--impure.
Options to override configuration settings:
-
--accept-flake-configEnable theaccept-flake-configsetting. -
--access-tokensvalue Set theaccess-tokenssetting. -
--allow-dirtyEnable theallow-dirtysetting. -
--allow-import-from-derivationEnable theallow-import-from-derivationsetting. -
--allow-new-privilegesEnable theallow-new-privilegessetting. -
--allow-symlinked-storeEnable theallow-symlinked-storesetting. -
--allow-unsafe-native-code-during-evaluationEnable theallow-unsafe-native-code-during-evaluationsetting. -
--allowed-impure-host-depsvalue Set theallowed-impure-host-depssetting. -
--allowed-urisvalue Set theallowed-urissetting. -
--allowed-usersvalue Set theallowed-userssetting. -
--auto-allocate-uidsEnable theauto-allocate-uidssetting. -
--auto-optimise-storeEnable theauto-optimise-storesetting. -
--bash-promptvalue Set thebash-promptsetting. -
--bash-prompt-prefixvalue Set thebash-prompt-prefixsetting. -
--bash-prompt-suffixvalue Set thebash-prompt-suffixsetting. -
--build-hookvalue Set thebuild-hooksetting. -
--build-poll-intervalvalue Set thebuild-poll-intervalsetting. -
--build-users-groupvalue Set thebuild-users-groupsetting. -
--buildersvalue Set thebuilderssetting. -
--builders-use-substitutesEnable thebuilders-use-substitutessetting. -
--commit-lockfile-summaryvalue Set thecommit-lockfile-summarysetting. -
--compress-build-logEnable thecompress-build-logsetting. -
--connect-timeoutvalue Set theconnect-timeoutsetting. -
--coresvalue Set thecoressetting. -
--diff-hookvalue Set thediff-hooksetting. -
--download-attemptsvalue Set thedownload-attemptssetting. -
--download-speedvalue Set thedownload-speedsetting. -
--eval-cacheEnable theeval-cachesetting. -
--experimental-featuresvalue Set theexperimental-featuressetting. -
--extra-access-tokensvalue Append to theaccess-tokenssetting. -
--extra-allowed-impure-host-depsvalue Append to theallowed-impure-host-depssetting. -
--extra-allowed-urisvalue Append to theallowed-urissetting. -
--extra-allowed-usersvalue Append to theallowed-userssetting. -
--extra-build-hookvalue Append to thebuild-hooksetting. -
--extra-experimental-featuresvalue Append to theexperimental-featuressetting. -
--extra-extra-platformsvalue Append to theextra-platformssetting. -
--extra-hashed-mirrorsvalue Append to thehashed-mirrorssetting. -
--extra-ignored-aclsvalue Append to theignored-aclssetting. -
--extra-nix-pathvalue Append to thenix-pathsetting. -
--extra-platformsvalue Set theextra-platformssetting. -
--extra-plugin-filesvalue Append to theplugin-filessetting. -
--extra-sandbox-pathsvalue Append to thesandbox-pathssetting. -
--extra-secret-key-filesvalue Append to thesecret-key-filessetting. -
--extra-substitutersvalue Append to thesubstituterssetting. -
--extra-system-featuresvalue Append to thesystem-featuressetting. -
--extra-trusted-public-keysvalue Append to thetrusted-public-keyssetting. -
--extra-trusted-substitutersvalue Append to thetrusted-substituterssetting. -
--extra-trusted-usersvalue Append to thetrusted-userssetting. -
--fallbackEnable thefallbacksetting. -
--filter-syscallsEnable thefilter-syscallssetting. -
--flake-registryvalue Set theflake-registrysetting. -
--fsync-metadataEnable thefsync-metadatasetting. -
--gc-reserved-spacevalue Set thegc-reserved-spacesetting. -
--hashed-mirrorsvalue Set thehashed-mirrorssetting. -
--http-connectionsvalue Set thehttp-connectionssetting. -
--http2Enable thehttp2setting. -
--id-countvalue Set theid-countsetting. -
--ignore-tryEnable theignore-trysetting. -
--ignored-aclsvalue Set theignored-aclssetting. -
--impersonate-linux-26Enable theimpersonate-linux-26setting. -
--keep-build-logEnable thekeep-build-logsetting. -
--keep-derivationsEnable thekeep-derivationssetting. -
--keep-env-derivationsEnable thekeep-env-derivationssetting. -
--keep-failedEnable thekeep-failedsetting. -
--keep-goingEnable thekeep-goingsetting. -
--keep-outputsEnable thekeep-outputssetting. -
--log-linesvalue Set thelog-linessetting. -
--max-build-log-sizevalue Set themax-build-log-sizesetting. -
--max-freevalue Set themax-freesetting. -
--max-jobsvalue Set themax-jobssetting. -
--max-silent-timevalue Set themax-silent-timesetting. -
--max-substitution-jobsvalue Set themax-substitution-jobssetting. -
--min-freevalue Set themin-freesetting. -
--min-free-check-intervalvalue Set themin-free-check-intervalsetting. -
--nar-buffer-sizevalue Set thenar-buffer-sizesetting. -
--narinfo-cache-negative-ttlvalue Set thenarinfo-cache-negative-ttlsetting. -
--narinfo-cache-positive-ttlvalue Set thenarinfo-cache-positive-ttlsetting. -
--netrc-filevalue Set thenetrc-filesetting. -
--nix-pathvalue Set thenix-pathsetting. -
--no-accept-flake-configDisable theaccept-flake-configsetting. -
--no-allow-dirtyDisable theallow-dirtysetting. -
--no-allow-import-from-derivationDisable theallow-import-from-derivationsetting. -
--no-allow-new-privilegesDisable theallow-new-privilegessetting. -
--no-allow-symlinked-storeDisable theallow-symlinked-storesetting. -
--no-allow-unsafe-native-code-during-evaluationDisable theallow-unsafe-native-code-during-evaluationsetting. -
--no-auto-allocate-uidsDisable theauto-allocate-uidssetting. -
--no-auto-optimise-storeDisable theauto-optimise-storesetting. -
--no-builders-use-substitutesDisable thebuilders-use-substitutessetting. -
--no-compress-build-logDisable thecompress-build-logsetting. -
--no-eval-cacheDisable theeval-cachesetting. -
--no-fallbackDisable thefallbacksetting. -
--no-filter-syscallsDisable thefilter-syscallssetting. -
--no-fsync-metadataDisable thefsync-metadatasetting. -
--no-http2Disable thehttp2setting. -
--no-ignore-tryDisable theignore-trysetting. -
--no-impersonate-linux-26Disable theimpersonate-linux-26setting. -
--no-keep-build-logDisable thekeep-build-logsetting. -
--no-keep-derivationsDisable thekeep-derivationssetting. -
--no-keep-env-derivationsDisable thekeep-env-derivationssetting. -
--no-keep-failedDisable thekeep-failedsetting. -
--no-keep-goingDisable thekeep-goingsetting. -
--no-keep-outputsDisable thekeep-outputssetting. -
--no-preallocate-contentsDisable thepreallocate-contentssetting. -
--no-print-missingDisable theprint-missingsetting. -
--no-pure-evalDisable thepure-evalsetting. -
--no-require-drop-supplementary-groupsDisable therequire-drop-supplementary-groupssetting. -
--no-require-sigsDisable therequire-sigssetting. -
--no-restrict-evalDisable therestrict-evalsetting. -
--no-run-diff-hookDisable therun-diff-hooksetting. -
--no-sandboxDisable sandboxing. -
--no-sandbox-fallbackDisable thesandbox-fallbacksetting. -
--no-show-traceDisable theshow-tracesetting. -
--no-substituteDisable thesubstitutesetting. -
--no-sync-before-registeringDisable thesync-before-registeringsetting. -
--no-trace-function-callsDisable thetrace-function-callssetting. -
--no-trace-verboseDisable thetrace-verbosesetting. -
--no-use-case-hackDisable theuse-case-hacksetting. -
--no-use-cgroupsDisable theuse-cgroupssetting. -
--no-use-registriesDisable theuse-registriessetting. -
--no-use-sqlite-walDisable theuse-sqlite-walsetting. -
--no-use-xdg-base-directoriesDisable theuse-xdg-base-directoriessetting. -
--no-warn-dirtyDisable thewarn-dirtysetting. -
--plugin-filesvalue Set theplugin-filessetting. -
--post-build-hookvalue Set thepost-build-hooksetting. -
--pre-build-hookvalue Set thepre-build-hooksetting. -
--preallocate-contentsEnable thepreallocate-contentssetting. -
--print-missingEnable theprint-missingsetting. -
--pure-evalEnable thepure-evalsetting. -
--relaxed-sandboxEnable sandboxing, but allow builds to disable it. -
--require-drop-supplementary-groupsEnable therequire-drop-supplementary-groupssetting. -
--require-sigsEnable therequire-sigssetting. -
--restrict-evalEnable therestrict-evalsetting. -
--run-diff-hookEnable therun-diff-hooksetting. -
--sandboxEnable sandboxing. -
--sandbox-build-dirvalue Set thesandbox-build-dirsetting. -
--sandbox-dev-shm-sizevalue Set thesandbox-dev-shm-sizesetting. -
--sandbox-fallbackEnable thesandbox-fallbacksetting. -
--sandbox-pathsvalue Set thesandbox-pathssetting. -
--secret-key-filesvalue Set thesecret-key-filessetting. -
--show-traceEnable theshow-tracesetting. -
--ssl-cert-filevalue Set thessl-cert-filesetting. -
--stalled-download-timeoutvalue Set thestalled-download-timeoutsetting. -
--start-idvalue Set thestart-idsetting. -
--storevalue Set thestoresetting. -
--substituteEnable thesubstitutesetting. -
--substitutersvalue Set thesubstituterssetting. -
--sync-before-registeringEnable thesync-before-registeringsetting. -
--systemvalue Set thesystemsetting. -
--system-featuresvalue Set thesystem-featuressetting. -
--tarball-ttlvalue Set thetarball-ttlsetting. -
--timeoutvalue Set thetimeoutsetting. -
--trace-function-callsEnable thetrace-function-callssetting. -
--trace-verboseEnable thetrace-verbosesetting. -
--trusted-public-keysvalue Set thetrusted-public-keyssetting. -
--trusted-substitutersvalue Set thetrusted-substituterssetting. -
--trusted-usersvalue Set thetrusted-userssetting. -
--use-case-hackEnable theuse-case-hacksetting. -
--use-cgroupsEnable theuse-cgroupssetting. -
--use-registriesEnable theuse-registriessetting. -
--use-sqlite-walEnable theuse-sqlite-walsetting. -
--use-xdg-base-directoriesEnable theuse-xdg-base-directoriessetting. -
--user-agent-suffixvalue Set theuser-agent-suffixsetting. -
--warn-dirtyEnable thewarn-dirtysetting.