FreeBSD Manual Pages
nix3-env-shell(1) General Commands Manual nix3-env-shell(1) Warning This program is experimental and its interface is subject to change. Name nix env shell - run a shell in which the specified packages are available 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 de- fault 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 pro- vides the specified installables. If no command 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 arbi- trary 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 areala script interpreter that will be in- voked by nix shell after it has obtained the dependencies and initialised the environment, and installables are the attribute names of the dependen- cies in Nixpkgs. The lines starting with #! nix specify options (see above). Note that you cannot write #! /usr/bin/env nix shell -i ... because many operating sys- tems only allow one argument in #! lines. For example, here is a Python script that depends on Python and the pret- tytable 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 requires 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 $href; } Sometimes you need to pass a simple Nix expression to customize a package like Terraform: #! /usr/bin/env nix #! nix shell --impure --expr `` #! nix with (import (builtins.getFlake ''nixpkgs'') {}); #! nix terraform.withPlugins (plugins: [ plugins.openstack ]) #! nix `` #! nix --command bash terraform "$@" Note You must use double backticks (``) when passing a simple Nix expres- sion 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 stable 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 revision of Nixpkgs: #!nix shell --override-input nixpkgs github:NixOS/nixpkgs/eabc38219184cc3e04a974fe31857d8e0eac098d You can also use a Nix expression to build your own dependencies. For exam- ple, 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 contains: with import <nixpkgs> {}; python3.withPackages (ps: with ps; [ prettytable ]) Options * --command / -c command args Command and arguments to be executed, defaulting to $SHELL * --stdin Read installables from the standard input. No default installable ap- plied. Common evaluation options * --arg name expr Pass the value expr as the argument name to Nix functions. * --arg-from-file name path Pass the contents of file path as the argument name to Nix functions. * --arg-from-stdin name Pass the contents of stdin as the argument name to Nix functions. * --argstr name string Pass the string string as the argument name to Nix functions. * --debugger Start an interactive environment if evaluation fails. * --eval-store store-url The URL of the Nix store to use for evaluation, i.e. to store deriva- tions (.drv files) and inputs referenced by them. * --impure Allow access to mutable paths and repositories. * --include / -I path Add path to search path entries used to resolve lookup paths This option may be given multiple times. Paths added through -I take precedence over the nix-path configuration setting and the NIX_PATH environment variable. * --override-flake original-ref resolved-ref Override the flake registries, redirecting original-ref to resolved-ref. Common flake-related options * --commit-lock-file Commit changes to the flake's lock file. * --inputs-from flake-url Use the inputs of the specified flake as registry entries. * --no-registries Don't allow lookups in the flake registries. DEPRECATED Use --no-use-registries instead. * --no-update-lock-file Do not allow any updates to the flake's lock file. * --no-write-lock-file Do not write the flake's newly generated lock file. * --output-lock-file flake-lock-path Write the given lock file instead of flake.lock within the top-level flake. * --override-input input-path flake-url Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file. * --recreate-lock-file Recreate the flake's lock file from scratch. DEPRECATED Use nix flake update instead. * --reference-lock-file flake-lock-path Read the given lock file instead of flake.lock within the top-level flake. * --update-input input-path Update a specific flake input (ignoring its previous entry in the lock file). DEPRECATED Use nix flake update instead. Logging-related options * --debug Set the logging verbosity level to `debug'. * --log-format format Set the format of log output; one of raw, internal-json, bar or bar- with-logs. * --print-build-logs / -L Print full build logs on standard error. * --quiet Decrease the logging verbosity level. * --verbose / -v Increase the logging verbosity level. Miscellaneous global options * --help Show usage information. * --offline Disable substituters and consider all previously downloaded files up-to- date. * --option name value Set the Nix configuration setting name to value (overriding nix.conf). * --refresh Consider all previously downloaded files out-of-date. * --repair During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths. * --version Show version information. Options that change environment variables * --ignore-env / -i Clear the entire environment, except for those specified with --keep- env-var. * --keep-env-var / -k name Keep the environment variable name, when using --ignore-env. * --set-env-var / -s name value Sets an environment variable name with value. * --unset-env-var / -u name Unset the environment variable name. Options that change the interpretation of installables * --expr expr Interpret installables as attribute paths relative to the Nix expression expr. * --file / -f file Interpret installables as attribute paths relative to the Nix expression stored in file. If file is the character -, then a Nix expression is read from standard input. Implies --impure. Note See man nix.conf 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+15.1.quarterly>