FreeBSD Manual Pages
nix3-env-shell(1) General Commands Manual nix3-env-shell(1) Warning This program is experimental <../../development/experimental- features.md#xp-feature-nix-command> and its interface is subject to change. Name nix env shell - run a shell in which the specified packages are avail- able Synopsis nix env shell [option...] installables... Examples • Start a shell providing youtube-dl from the nixpkgs flake: # nix shell nixpkgs#youtube-dl # youtube-dl --version 2020.11.01.1 • Start a shell providing GNU Hello from NixOS 20.03: # nix shell nixpkgs/nixos-20.03#hello • Run GNU Hello: # nix shell nixpkgs#hello --command hello --greeting 'Hi everybody!' Hi everybody! • Run multiple commands in a shell environment: # nix shell nixpkgs#gnumake --command sh -c "cd src && make" • Run GNU Hello in a chroot store: # nix shell --store ~/my-nix nixpkgs#hello --command hello • Start a shell providing GNU Hello in a chroot store: # nix shell --store ~/my-nix nixpkgs#hello nixpkgs#bashInteractive --command bash Note that it's necessary to specify bash explicitly because your default shell (e.g. /bin/bash) generally will not exist in the chroot. Description nix shell runs a command in an environment in which the $PATH variable provides the specified installables <./nix.md#installables>. If no com- mand is specified, it starts the default shell of your user account specified by $SHELL. Use as a #!-interpreter You can use nix as a script interpreter to allow scripts written in ar- bitrary languages to obtain their own dependencies via Nix. This is done by starting the script with the following lines: #! /usr/bin/env nix #! nix shell installables --command real-interpreter where real-interpreter is the real script interpreter that will be in- voked by nix shell after it has obtained the dependencies and ini- tialised the environment, and installables are the attribute names of the dependencies in Nixpkgs. The lines starting with #! nix specify options (see above). Note that you cannot write #! /usr/bin/env nix shell -i ... because many operat- ing systems only allow one argument in #! lines. For example, here is a Python script that depends on Python and the prettytable package: #! /usr/bin/env nix #! nix shell github:tomberek/-#python3With.prettytable --command python import prettytable # Print a simple table. t = prettytable.PrettyTable(["N", "N^2"]) for n in range(1, 10): t.add_row([n, n * n]) print(t) Similarly, the following is a Perl script that specifies that it re- quires Perl and the HTML::TokeParser::Simple and LWP packages: #! /usr/bin/env nix #! nix shell github:tomberek/-#perlWith.HTMLTokeParserSimple.LWP --command perl -x use HTML::TokeParser::Simple; # Fetch nixos.org and print all hrefs. my $p = HTML::TokeParser::Simple->new(url => 'http://nixos.org/'); while (my $token = $p->get_tag("a")) { my $href = $token->get_attr("href"); print "$href\n" if $href; } Sometimes you need to pass a simple Nix expression to customize a pack- age like Terraform: #! /usr/bin/env nix #! nix shell --impure --expr `` #! nix with (import (builtins.getFlake ''nixpkgs'') {}); #! nix terraform.withPlugins (plugins: [ plugins.openstack ]) #! nix `` #! nix --command bash terraform "$@" Note You must use double backticks (``) when passing a simple Nix ex- pression in a nix shell shebang. Finally, using the merging of multiple nix shell shebangs the following Haskell script uses a specific branch of Nixpkgs/NixOS (the 21.11 sta- ble branch): #!/usr/bin/env nix #!nix shell --override-input nixpkgs github:NixOS/nixpkgs/nixos-21.11 #!nix github:tomberek/-#haskellWith.download-curl.tagsoup --command runghc import Network.Curl.Download import Text.HTML.TagSoup import Data.Either import Data.ByteString.Char8 (unpack) -- Fetch nixos.org and print all hrefs. main = do resp <- openURI "https://nixos.org/" let tags = filter (isTagOpenName "a") $ parseTags $ unpack $ fromRight undefined resp let tags' = map (fromAttrib "href") tags mapM_ putStrLn $ filter (/= "") tags' If you want to be even more precise, you can specify a specific revi- sion of Nixpkgs: #!nix shell --override-input nixpkgs github:NixOS/nixpkgs/eabc38219184cc3e04a974fe31857d8e0eac098d You can also use a Nix expression to build your own dependencies. For example, the Python example could have been written as: #! /usr/bin/env nix #! nix shell --impure --file deps.nix -i python where the file deps.nix in the same directory as the #!-script con- tains: with import <nixpkgs> {}; python3.withPackages (ps: with ps; [ prettytable ]) Options • --command <#opt-command> / -c command args Command and arguments to be executed, defaulting to $SHELL • --stdin <#opt-stdin> Read installables from the standard input. No default installable applied. Common evaluation options • --arg <#opt-arg> name expr Pass the value expr as the argument name to Nix functions. • --arg-from-file <#opt-arg-from-file> name path Pass the contents of file path as the argument name to Nix func- tions. • --arg-from-stdin <#opt-arg-from-stdin> name Pass the contents of stdin as the argument name to Nix functions. • --argstr <#opt-argstr> name string Pass the string string as the argument name to Nix functions. • --debugger <#opt-debugger> Start an interactive environment if evaluation fails. • --eval-store <#opt-eval-store> store-url The URL of the Nix store <../../store/types/index.md#store-url- format> to use for evaluation, i.e. to store derivations (.drv files) and inputs referenced by them. • --impure <#opt-impure> Allow access to mutable paths and repositories. • --include <#opt-include> / -I path Add path to search path entries used to resolve lookup paths <../../language/constructs/lookup-path.md> This option may be given multiple times. Paths added through -I take precedence over the nix-path configura- tion setting <../../command-ref/conf-file.md#conf-nix-path> and the NIX_PATH environment variable <../../command-ref/env-common.md#env- NIX_PATH>. • --override-flake <#opt-override-flake> original-ref resolved-ref Override the flake registries, redirecting original-ref to resolved- ref. Common flake-related options • --commit-lock-file <#opt-commit-lock-file> Commit changes to the flake's lock file. • --inputs-from <#opt-inputs-from> flake-url Use the inputs of the specified flake as registry entries. • --no-registries <#opt-no-registries> Don't allow lookups in the flake registries. DEPRECATED Use --no-use-registries <../../command-ref/conf-file.md#conf- use-registries> instead. • --no-update-lock-file <#opt-no-update-lock-file> Do not allow any updates to the flake's lock file. • --no-write-lock-file <#opt-no-write-lock-file> Do not write the flake's newly generated lock file. • --output-lock-file <#opt-output-lock-file> flake-lock-path Write the given lock file instead of flake.lock within the top-level flake. • --override-input <#opt-override-input> input-path flake-url Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file. • --recreate-lock-file <#opt-recreate-lock-file> Recreate the flake's lock file from scratch. DEPRECATED Use nix flake update <../../command-ref/new-cli/nix3-flake- update.md> instead. • --reference-lock-file <#opt-reference-lock-file> flake-lock-path Read the given lock file instead of flake.lock within the top-level flake. • --update-input <#opt-update-input> input-path Update a specific flake input (ignoring its previous entry in the lock file). DEPRECATED Use nix flake update <../../command-ref/new-cli/nix3-flake- update.md> instead. Logging-related options • --debug <#opt-debug> Set the logging verbosity level to `debug'. • --log-format <#opt-log-format> format Set the format of log output; one of raw, internal-json, bar or bar- with-logs. • --print-build-logs <#opt-print-build-logs> / -L Print full build logs on standard error. • --quiet <#opt-quiet> Decrease the logging verbosity level. • --verbose <#opt-verbose> / -v Increase the logging verbosity level. Miscellaneous global options • --help <#opt-help> Show usage information. • --offline <#opt-offline> Disable substituters and consider all previously downloaded files up-to-date. • --option <#opt-option> name value Set the Nix configuration setting name to value (overriding nix.conf). • --refresh <#opt-refresh> Consider all previously downloaded files out-of-date. • --repair <#opt-repair> During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths. • --version <#opt-version> Show version information. Options that change environment variables • --ignore-env <#opt-ignore-env> / -i Clear the entire environment, except for those specified with --keep-env-var. • --keep-env-var <#opt-keep-env-var> / -k name Keep the environment variable name, when using --ignore-env. • --set-env-var <#opt-set-env-var> / -s name value Sets an environment variable name with value. • --unset-env-var <#opt-unset-env-var> / -u name Unset the environment variable name. Options that change the interpretation of installables • --expr <#opt-expr> expr Interpret installables <../../command-ref/new- cli/nix.md#installables> as attribute paths relative to the Nix ex- pression expr. • --file <#opt-file> / -f file Interpret installables <../../command-ref/new- cli/nix.md#installables> as attribute paths relative to the Nix ex- pression stored in file. If file is the character -, then a Nix ex- pression is read from standard input. Implies --impure. Note See man nix.conf <../../command-ref/conf-file.md#command-line-flags> for overriding configuration settings with command line flags. nix3-env-shell(1)
Name | Synopsis | Examples | Description | Options
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=nix3-env-shell&sektion=1&manpath=FreeBSD+Ports+15.0>