52 lines
1.6 KiB
Markdown
52 lines
1.6 KiB
Markdown
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# Ad-Hoc Package Management {#sec-ad-hoc-packages}
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With the command `nix-env`, you can install and uninstall packages from
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the command line. For instance, to install Mozilla Thunderbird:
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```ShellSession
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$ nix-env -iA nixos.thunderbird
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```
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If you invoke this as root, the package is installed in the Nix profile
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`/nix/var/nix/profiles/default` and visible to all users of the system;
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otherwise, the package ends up in
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`/nix/var/nix/profiles/per-user/username/profile` and is not visible to
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other users. The `-A` flag specifies the package by its attribute name;
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without it, the package is installed by matching against its package
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name (e.g. `thunderbird`). The latter is slower because it requires
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matching against all available Nix packages, and is ambiguous if there
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are multiple matching packages.
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Packages come from the NixOS channel. You typically upgrade a package by
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updating to the latest version of the NixOS channel:
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```ShellSession
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$ nix-channel --update nixos
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```
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and then running `nix-env -i` again. Other packages in the profile are
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*not* affected; this is the crucial difference with the declarative
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style of package management, where running `nixos-rebuild switch` causes
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all packages to be updated to their current versions in the NixOS
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channel. You can however upgrade all packages for which there is a newer
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version by doing:
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```ShellSession
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$ nix-env -u '*'
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```
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A package can be uninstalled using the `-e` flag:
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```ShellSession
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$ nix-env -e thunderbird
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```
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Finally, you can roll back an undesirable `nix-env` action:
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```ShellSession
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$ nix-env --rollback
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```
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`nix-env` has many more flags. For details, see the nix-env(1) manpage or
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the Nix manual.
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