nix-env-install - Man Page

nix-env {--install | -i} args… [{--prebuilt-only | -b}] [{--attr | -A}] [--from-expression] [-E] [--from-profile path] [--preserve-installed | -P] [--remove-all | -r] [--priority priority]

The --install operation creates a new user environment. It is based on the current generation of the active profile, to which a set of store paths described by args is added.

The arguments args map to store paths in a number of possible ways:

• By default, args is a set of names denoting derivations in the default Nix expression. These are realised, and the resulting output paths are installed. Currently installed derivations with a name equal to the name of a derivation being added are removed unless the option --preserve-installed is specified.

  If there are multiple derivations matching a name in args that have the same name (e.g., gcc-3.3.6 and gcc-4.1.1), then the derivation with the highest priority is used. A derivation can define a priority by declaring the meta.priority attribute. This attribute should be a number, with a higher value denoting a lower priority. The default priority is 5.

  If there are multiple matching derivations with the same priority, then the derivation with the highest version will be installed.

  You can force the installation of multiple derivations with the same name by being specific about the versions. For instance, nix-env --install gcc-3.3.6 gcc-4.1.1 will install both version of GCC (and will probably cause a user environment conflict!).

• If --attr / -A is specified, the arguments are attribute paths that select attributes from the default Nix expression. This is faster than using derivation names and unambiguous. Show the attribute paths of available packages with nix-env --query:

nix-env --query --available --attr-path

• If --from-profile path is given, args is a set of names denoting installed store paths in the profile path. This is an easy way to copy user environment elements from one profile to another.
• If --from-expression is given, args are Nix language functions that are called with the default Nix expression as their single argument. The derivations returned by those function calls are installed. This allows derivations to be specified in an unambiguous way, which is necessary if there are multiple derivations with the same name.
• If --priority priority is given, the priority of the derivations being installed is set to priority. This can be used to override the priority of the derivations being installed. This is useful if args are store paths, which don't have any priority information.
• If args are store paths that point to store derivations, then those store derivations are realised, and the resulting output paths are installed.
• If args are store paths that do not point to store derivations, then these are realised and installed.

• By default all outputs are installed for each store derivation. This can be overridden by adding a meta.outputsToInstall attribute on the derivation listing a subset of the output names.

  Example:

  The file example.nix defines a derivation with two outputs foo and bar, each containing a file.

# example.nix
let
pkgs = import <nixpkgs> {};
command = ''
  ${pkgs.coreutils}/bin/mkdir -p $foo $bar
  echo foo > $foo/foo-file
  echo bar > $bar/bar-file
​'';
in
derivation {
name = "example";
builder = "${pkgs.bash}/bin/bash";
args = [ "-c" command ];
outputs = [ "foo" "bar" ];
system = builtins.currentSystem;
}

Installing from this Nix expression will make files from both outputs appear in the current profile.

$ nix-env --install --file example.nix
installing 'example'
$ ls ~/.nix-profile
foo-file
bar-file
manifest.nix

Adding meta.outputsToInstall to that derivation will make nix-env only install files from the specified outputs.

# example-outputs.nix
import ./example.nix // { meta.outputsToInstall = [ "bar" ]; }

$ nix-env --install --file example-outputs.nix
installing 'example'
$ ls ~/.nix-profile
bar-file
manifest.nix

• --prebuilt-only / -b

  Use only derivations for which a substitute is registered, i.e., there is a pre-built binary available that can be downloaded in lieu of building the derivation. Thus, no packages will be built from source.

• --preserve-installed / -P

  Do not remove derivations with a name matching one of the derivations being installed. Usually, trying to have two versions of the same package installed in the same generation of a profile will lead to an error in building the generation, due to file name clashes between the two versions. However, this is not the case for all packages.

• --remove-all / -r

  Remove all previously installed packages first. This is equivalent to running nix-env --uninstall '.*' first, except that everything happens in a single transaction.

The following options are allowed for all nix-env operations, but may not always have an effect.

• --file / -f path

  Specifies the Nix expression (designated below as the active Nix expression) used by the --install, --upgrade, and --query --available operations to obtain derivations. The default is ~/.nix-defexpr.

  If the argument starts with http:// or https://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must include a single top-level directory containing at least a file named default.nix.

• --profile / -p path

  Specifies the profile to be used by those operations that operate on a profile (designated below as the active profile). A profile is a sequence of user environments called generations, one of which is the current generation.

• --dry-run

  For the --install, --upgrade, --uninstall, --switch-generation, --delete-generations and --rollback operations, this flag will cause nix-env to print what would be done if this flag had not been specified, without actually doing it.

  --dry-run also prints out which paths will be substituted (i.e., downloaded) and which paths will be built from source (because no substitute is available).

• --system-filter system

  By default, operations such as --query --available show derivations matching any platform. This option allows you to use derivations for the specified platform system.

Most Nix commands accept the following command-line options:

• --help

  Prints out a summary of the command syntax and exits.

• --version

  Prints out the Nix version number on standard output and exits.

• --verbose / -v

  Increases the level of verbosity of diagnostic messages printed on standard error. For each Nix operation, the information printed on standard output is well-defined; any diagnostic information is printed on standard error, never on standard output.

  This option may be specified repeatedly. Currently, the following verbosity levels exist:

  • 0 “Errors only”

  Only print messages explaining why the Nix invocation failed.

  • 1 “Informational”

  Print useful messages about what Nix is doing. This is the default.

  • 2 “Talkative”

  Print more informational messages.

  • 3 “Chatty”

  Print even more informational messages.

  • 4 “Debug”

  Print debug information.

  • 5 “Vomit”

  Print vast amounts of debug information.

• --quiet

  Decreases the level of verbosity of diagnostic messages printed on standard error. This is the inverse option to -v / --verbose.

  This option may be specified repeatedly. See the previous verbosity levels list.

• --log-format format

  This option can be used to change the output of the log format, with format being one of:

  • raw

  This is the raw format, as outputted by nix-build.

  • internal-json

  Outputs the logs in a structured manner.

  Warning

  While the schema itself is relatively stable, the format of the error-messages (namely of the msg-field) can change between releases.

  • bar

  Only display a progress bar during the builds.

  • bar-with-logs

  Display the raw logs, with the progress bar at the bottom.

• --no-build-output / -Q

  By default, output written by builders to standard output and standard error is echoed to the Nix command's standard error. This option suppresses this behaviour. Note that the builder's standard output and error are always written to a log file in prefix/nix/var/log/nix.

• --max-jobs / -j number

  Sets the maximum number of build jobs that Nix will perform in parallel to the specified number. Specify auto to use the number of CPUs in the system. The default is specified by the max-jobs configuration setting, which itself defaults to 1. A higher value is useful on SMP systems or to exploit I/O latency.

  Setting it to 0 disallows building on the local machine, which is useful when you want builds to happen only on remote builders.

• --cores

  Sets the value of the NIX_BUILD_CORES environment variable in the invocation of builders. Builders can use this variable at their discretion to control the maximum amount of parallelism. For instance, in Nixpkgs, if the derivation attribute enableParallelBuilding is set to true, the builder passes the -jN flag to GNU Make. It defaults to the value of the cores configuration setting, if set, or 1 otherwise. The value 0 means that the builder should use all available CPU cores in the system.

• --max-silent-time

  Sets the maximum number of seconds that a builder can go without producing any data on standard output or standard error. The default is specified by the max-silent-time configuration setting. 0 means no time-out.

• --timeout

  Sets the maximum number of seconds that a builder can run. The default is specified by the timeout configuration setting. 0 means no timeout.

• --keep-going / -k

  Keep going in case of failed builds, to the greatest extent possible. That is, if building an input of some derivation fails, Nix will still build the other inputs, but not the derivation itself. Without this option, Nix stops if any build fails (except for builds of substitutes), possibly killing builds in progress (in case of parallel or distributed builds).

• --keep-failed / -K

  Specifies that in case of a build failure, the temporary directory (usually in /tmp) in which the build takes place should not be deleted. The path of the build directory is printed as an informational message.

• --fallback

  Whenever Nix attempts to build a derivation for which substitutes are known for each output path, but realising the output paths through the substitutes fails, fall back on building the derivation.

  The most common scenario in which this is useful is when we have registered substitutes in order to perform binary distribution from, say, a network repository. If the repository is down, the realisation of the derivation will fail. When this option is specified, Nix will build the derivation instead. Thus, installation from binaries falls back on installation from source. This option is not the default since it is generally not desirable for a transient failure in obtaining the substitutes to lead to a full build from source (with the related consumption of resources).

• --readonly-mode

  When this option is used, no attempt is made to open the Nix database. Most Nix operations do need database access, so those operations will fail.

• --arg name value

  This option is accepted by nix-env, nix-instantiate, nix-shell and nix-build. When evaluating Nix expressions, the expression evaluator will automatically try to call functions that it encounters. It can automatically call functions for which every argument has a default value (e.g., { argName ?  defaultValue }: ...).

  With --arg, you can also call functions that have arguments without a default value (or override a default value). That is, if the evaluator encounters a function with an argument named name, it will call it with value value.

  For instance, the top-level default.nix in Nixpkgs is actually a function:

{ # The system (e.g., `i686-linux') for which to build the packages.
system ? builtins.currentSystem
​...
}: ...

So if you call this Nix expression (e.g., when you do nix-env --install --attr pkgname), the function will be called automatically using the value builtins.currentSystem for the system argument. You can override this using --arg, e.g., nix-env --install --attr pkgname --arg system \"i686-freebsd\". (Note that since the argument is a Nix string literal, you have to escape the quotes.)

• --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 value

  This option is like --arg, only the value is not a Nix expression but a string. So instead of --arg system \"i686-linux\" (the outer quotes are to keep the shell happy) you can say --argstr system i686-linux.

• --attr / -A attrPath

  Select an attribute from the top-level Nix expression being evaluated. (nix-env, nix-instantiate, nix-build and nix-shell only.) The attribute path attrPath is a sequence of attribute names separated by dots. For instance, given a top-level Nix expression e, the attribute path xorg.xorgserver would cause the expression e.xorg.xorgserver to be used. See nix-env --install for some concrete examples.

  In addition to attribute names, you can also specify array indices. For instance, the attribute path foo.3.bar selects the bar attribute of the fourth element of the array in the foo attribute of the top-level expression.

• --eval-store store-url

  The URL to the Nix store to use for evaluation, i.e. where to store derivations (.drv files) and inputs referenced by them.

• --expr / -E

  Interpret the command line arguments as a list of Nix expressions to be parsed and evaluated, rather than as a list of file names of Nix expressions. (nix-instantiate, nix-build and nix-shell only.)

  For nix-shell, this option is commonly used to give you a shell in which you can build the packages returned by the expression. If you want to get a shell which contain the built packages ready for use, give your expression to the nix-shell --packages convenience flag instead.

• -I / --include path

  Add an entry to the list of search paths 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.

• --impure

  Allow access to mutable paths and repositories.

• --option name value

  Set the Nix configuration option name to value. This overrides settings in the Nix configuration file (see nix.conf5).

• --repair

  Fix corrupted or missing store paths by redownloading or rebuilding them. Note that this is slow because it requires computing a cryptographic hash of the contents of every path in the closure of the build. Also note the warning under nix-store --repair-path.

  Note

  See man nix.conf for overriding configuration settings with command line flags.

• NIX_PROFILE

  Location of the Nix profile. Defaults to the target of the symlink ~/.nix-profile, if it exists, or /nix/var/nix/profiles/default otherwise.

Most Nix commands interpret the following environment variables.

$ mkdir /nix
$ mount -o bind /mnt/otherdisk/nix /nix

To install a package using a specific attribute path from the active Nix expression:

$ nix-env --install --attr gcc40mips
installing `gcc-4.0.2'
$ nix-env --install --attr xorg.xorgserver
installing `xorg-server-1.2.0'

To install a specific version of gcc using the derivation name:

$ nix-env --install gcc-3.3.2
installing `gcc-3.3.2'
uninstalling `gcc-3.1'

Using attribute path for selecting a package is preferred, as it is much faster and there will not be multiple matches.

Note the previously installed version is removed, since --preserve-installed was not specified.

To install an arbitrary version:

$ nix-env --install gcc
installing `gcc-3.3.2'

To install all derivations in the Nix expression foo.nix:

$ nix-env --file ~/foo.nix --install '.*'

To copy the store path with symbolic name gcc from another profile:

$ nix-env --install --from-profile /nix/var/nix/profiles/foo gcc

To install a specific store derivation:

$ nix-env --install /nix/store/8la6y31fmm6i4wfmby6avly1wf718xnj-gcc-3.4.3.drv

To install a specific output path:

$ nix-env --install /nix/store/y3cgx0xj1p4iv9x0pnnmdhr8iyg741vk-gcc-3.4.3

To install from a Nix expression specified on the command-line:

$ nix-env --file ./foo.nix --install --expr \
    'f: (f {system = "i686-linux";}).subversionWithJava'

I.e., this evaluates to (f: (f {system = "i686-linux";}).subversionWithJava) (import ./foo.nix), thus selecting the subversionWithJava attribute from the set returned by calling the function defined in ./foo.nix.

A dry-run tells you which paths will be downloaded or built from source:

$ nix-env --file '<nixpkgs>' --install --attr hello --dry-run
(dry run; not doing anything)
installing ‘hello-2.10’
this path will be fetched (0.04 MiB download, 0.19 MiB unpacked):
  /nix/store/ikwkxz4wwlp2g1428n7dy729cg1d9hin-hello-2.10
  ...

To install Firefox from the latest revision in the Nixpkgs/NixOS 14.12 channel:

$ nix-env --file https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz --install --attr firefox