nix-super/doc/manual/source/command-ref/nix-env/set-flag.md
John Ericson eb7d7780b1 Rename doc/manual{src -> source}
This is needed to avoid this
https://github.com/mesonbuild/meson/issues/13774 when we go back to
making our subproject directory `src`.
2024-10-14 11:21:24 -04:00

82 lines
2.5 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

# Name
`nix-env --set-flag` - modify meta attributes of installed packages
# Synopsis
`nix-env` `--set-flag` *name* *value* *drvnames*
# Description
The `--set-flag` operation allows meta attributes of installed packages
to be modified. There are several attributes that can be usefully
modified, because they affect the behaviour of `nix-env` or the user
environment build script:
- `priority` can be changed to resolve filename clashes. The user
environment build script uses the `meta.priority` attribute of
derivations to resolve filename collisions between packages. Lower
priority values denote a higher priority. For instance, the GCC
wrapper package and the Binutils package in Nixpkgs both have a file
`bin/ld`, so previously if you tried to install both you would get a
collision. Now, on the other hand, the GCC wrapper declares a higher
priority than Binutils, so the formers `bin/ld` is symlinked in the
user environment.
- `keep` can be set to `true` to prevent the package from being
upgraded or replaced. This is useful if you want to hang on to an
older version of a package.
- `active` can be set to `false` to “disable” the package. That is, no
symlinks will be generated to the files of the package, but it
remains part of the profile (so it wont be garbage-collected). It
can be set back to `true` to re-enable the package.
{{#include ./opt-common.md}}
{{#include ../opt-common.md}}
{{#include ../env-common.md}}
# Examples
To prevent the currently installed Firefox from being upgraded:
```console
$ nix-env --set-flag keep true firefox
```
After this, `nix-env --upgrade ` will ignore Firefox.
To disable the currently installed Firefox, then install a new Firefox
while the old remains part of the profile:
```console
$ nix-env --query
firefox-2.0.0.9 (the current one)
$ nix-env --preserve-installed --install firefox-2.0.0.11
installing `firefox-2.0.0.11'
building path(s) `/nix/store/myy0y59q3ig70dgq37jqwg1j0rsapzsl-user-environment'
collision between `/nix/store/...-firefox-2.0.0.11/bin/firefox'
and `/nix/store/...-firefox-2.0.0.9/bin/firefox'.
(i.e., cant have two active at the same time)
$ nix-env --set-flag active false firefox
setting flag on `firefox-2.0.0.9'
$ nix-env --preserve-installed --install firefox-2.0.0.11
installing `firefox-2.0.0.11'
$ nix-env --query
firefox-2.0.0.11 (the enabled one)
firefox-2.0.0.9 (the disabled one)
```
To make files from `binutils` take precedence over files from `gcc`:
```console
$ nix-env --set-flag priority 5 binutils
$ nix-env --set-flag priority 10 gcc
```