nix-env(1)

Name
nix-env - manipulate or query Nix user environments

Synopsis
nix-env operation [options] [arguments…] [--option name value] [--arg name value] [--argstr name value] [{--file | -f} path] [{--profile | -p} path] [--system-filter system] [--dry-run]

Description
The command nix-env is used to manipulate Nix user environments. User environments are sets of software packages available to a user at some point in time. In other words, they are a synthesised view of the programs available in the Nix store. There may be many user environments: different users can have different environments, and individual users can switch between different environments.

nix-env takes exactly one operation flag which indicates the subcommand to be performed. The following operations are available:

•   --install

•   --upgrade

•   --uninstall

•   --set

•   --set-flag

•   --query

•   --switch-profile

•   --list-generations

•   --delete-generations

•   --switch-generation

•   --rollback

These pages can be viewed offline:

•   man nix-env-<operation>.

    Example: man nix-env-install

•   nix-env --help --<operation>

    Example: nix-env --help --install

Selectors
Several commands, such as nix-env -q and nix-env -i, take a list of arguments that specify the packages on which to operate. These are extended regular expressions that must match the entire name of the package. (For details on regular expressions, see regex(7).) The match is case-sensitive. The regular expression can optionally be followed by a dash and a version number; if omitted, any version of the package will match. Here are some examples:

•   firefox
    Matches the package name firefox and any version.

•   firefox-32.0
    Matches the package name firefox and version 32.0.

•   gtk\\+
    Matches the package name gtk+. The + character must be escaped using a backslash to prevent it from being interpreted as a quantifier, and the backslash must be escaped in turn with another backslash to ensure that the shell passes it on.

•   .\*
    Matches any package name. This is the default for most commands.

•   '.*zip.*'
    Matches any package name containing the string zip. Note the dots: '*zip*' does not work, because in a regular expression, the character * is interpreted as a quantifier.

•   '.*(firefox|chromium).*'
    Matches any package name containing the strings firefox or chromium.

Files

•   ~/.nix-defexpr
    The source for the default Nix expressions used by the --install, --upgrade, and --query --available operations to obtain derivations. The --file option may be used to override this default.

    If ~/.nix-defexpr is a file, it is loaded as a Nix expression. If the expression is a set, it is used as the default Nix expression. If the expression is a function, an empty set is passed as argument and the return value is used as the default Nix expression.

    If ~/.nix-defexpr is a directory containing a default.nix file, that file is loaded as in the above paragraph.

    If ~/.nix-defexpr is a directory without a default.nix file, then its contents (both files and subdirectories) are loaded as Nix expressions. The expressions are combined into a single set, each expression under an attribute with the same name as the original file or subdirectory.

    For example, if ~/.nix-defexpr contains two files, foo.nix and bar.nix, then the default Nix expression will essentially be

    {
      foo = import ~/.nix-defexpr/foo.nix;
      bar = import ~/.nix-defexpr/bar.nix;
    }

    The file manifest.nix is always ignored. Subdirectories without a default.nix file are traversed recursively in search of more Nix expressions, but the names of these intermediate directories are not added to the attribute paths of the default Nix expression.

    The command nix-channel places symlinks to the downloaded Nix expressions from each subscribed channel in this directory.

•   ~/.nix-profile
    A symbolic link to the user’s current profile. By default, this symlink points to prefix/var/nix/profiles/default. The PATH environment variable should include ~/.nix-profile/bin for the user environment to be visible to the user.