Per #41731 (comment), This cleans up
the tests for `spack gc` by replacing

```python
assert <string> in find()
```

with the more precise

```python
assert mutable_database.query_local(<string>)
```

Per #41731 (comment), This cleans up
the tests for `spack gc` by replacing

```python
assert <string> in find()
```

with the more precise

```python
assert mutable_database.query_local(<string>)
```

…k#41731)

This adds a few options to `spack gc`.

One to give you a little more control over dependencies:

* `-b` / `--keep-build-dependencies`: By default, `spack gc` considers build dependencies to be "no longer needed" once their dependents are installed. With this option, we'll keep build dependencies of needed installations as well.

And two more to make working with environments easier:

* `-E` / `--except-any-environment`: Garbage collect anything NOT needed by an environment. `spack gc -E` and `spack gc -bE` are now easy ways to get rid of everytihng not used by some environment.

* `-e` / `--except-environment` `ENV`: Instead of considering all environments, garbage collect everything not needed by a *specific* environment. Note that you can use this with `-E` to add directory environments to the list of considered envs, e.g.:

      spack gc -E -e /path/to/direnv1 -e /path/to/direnv2 #...

- [x] rework `unused_specs()` method on DB to add options for roots and deptypes
- [x] add `all_hashes()` method on DB
- [x] rework `spack gc` command to add 3 more options
- [x] tests

Per spack#41731 (comment), This cleans up
the tests for `spack gc` by replacing

```python
assert <string> in find()
```

with the more precise

```python
assert mutable_database.query_local(<string>)
```

…k#41731)

This adds a few options to `spack gc`.

One to give you a little more control over dependencies:

* `-b` / `--keep-build-dependencies`: By default, `spack gc` considers build dependencies to be "no longer needed" once their dependents are installed. With this option, we'll keep build dependencies of needed installations as well.

And two more to make working with environments easier:

* `-E` / `--except-any-environment`: Garbage collect anything NOT needed by an environment. `spack gc -E` and `spack gc -bE` are now easy ways to get rid of everytihng not used by some environment.

* `-e` / `--except-environment` `ENV`: Instead of considering all environments, garbage collect everything not needed by a *specific* environment. Note that you can use this with `-E` to add directory environments to the list of considered envs, e.g.:

      spack gc -E -e /path/to/direnv1 -e /path/to/direnv2 #...

- [x] rework `unused_specs()` method on DB to add options for roots and deptypes
- [x] add `all_hashes()` method on DB
- [x] rework `spack gc` command to add 3 more options
- [x] tests

Per spack#41731 (comment), This cleans up
the tests for `spack gc` by replacing

```python
assert <string> in find()
```

with the more precise

```python
assert mutable_database.query_local(<string>)
```

…k#41731)

This adds a few options to `spack gc`.

One to give you a little more control over dependencies:

* `-b` / `--keep-build-dependencies`: By default, `spack gc` considers build dependencies to be "no longer needed" once their dependents are installed. With this option, we'll keep build dependencies of needed installations as well.

And two more to make working with environments easier:

* `-E` / `--except-any-environment`: Garbage collect anything NOT needed by an environment. `spack gc -E` and `spack gc -bE` are now easy ways to get rid of everytihng not used by some environment.

* `-e` / `--except-environment` `ENV`: Instead of considering all environments, garbage collect everything not needed by a *specific* environment. Note that you can use this with `-E` to add directory environments to the list of considered envs, e.g.:

      spack gc -E -e /path/to/direnv1 -e /path/to/direnv2 #...

- [x] rework `unused_specs()` method on DB to add options for roots and deptypes
- [x] add `all_hashes()` method on DB
- [x] rework `spack gc` command to add 3 more options
- [x] tests

Per spack#41731 (comment), This cleans up
the tests for `spack gc` by replacing

```python
assert <string> in find()
```

with the more precise

```python
assert mutable_database.query_local(<string>)
```

This PR adds a sub-command to `spack env` (`track`) which allows users to add/link
anonymous environments into their installation as named environments. This allows
users to more easily track their installed packages and the environments they're
dependencies of. For example, with the addition of #41731 it's now easier to remove
all packages not required by any environments with,

```
spack gc -bE
```

#### Usage
```
spack env track /path/to/env
==> Linked environment in /path/to/env
==> You can activate this environment with:
==>     spack env activate env
```

By default `track /path/to/env` will use the last directory in the path as the name of 
the environment. However users may customize the name of the linked environment
with `-n | --name`. Shown below.
```
spack env track /path/to/env --name foo 
==> Tracking environment in /path/to/env
==> You can activate this environment with:
==>     spack env activate foo
```

When removing a linked environment, Spack will remove the link to the environment
but will keep the structure of the environment within the directory. This will allow
users to remove a linked environment from their installation without deleting it from
a shared repository.

There is a `spack env untrack` command that can be used to *only* untrack a tracked
environment -- it will fail if it is used on a managed environment.  Users can also use
`spack env remove` to untrack an environment.

This allows users to continue to share environments in git repositories  while also having
the dependencies of those environments be remembered by Spack.

---------

Co-authored-by: Todd Gamblin <[email protected]>

This PR adds a sub-command to `spack env` (`track`) which allows users to add/link
anonymous environments into their installation as named environments. This allows
users to more easily track their installed packages and the environments they're
dependencies of. For example, with the addition of spack#41731 it's now easier to remove
all packages not required by any environments with,

```
spack gc -bE
```

#### Usage
```
spack env track /path/to/env
==> Linked environment in /path/to/env
==> You can activate this environment with:
==>     spack env activate env
```

By default `track /path/to/env` will use the last directory in the path as the name of 
the environment. However users may customize the name of the linked environment
with `-n | --name`. Shown below.
```
spack env track /path/to/env --name foo 
==> Tracking environment in /path/to/env
==> You can activate this environment with:
==>     spack env activate foo
```

When removing a linked environment, Spack will remove the link to the environment
but will keep the structure of the environment within the directory. This will allow
users to remove a linked environment from their installation without deleting it from
a shared repository.

There is a `spack env untrack` command that can be used to *only* untrack a tracked
environment -- it will fail if it is used on a managed environment.  Users can also use
`spack env remove` to untrack an environment.

This allows users to continue to share environments in git repositories  while also having
the dependencies of those environments be remembered by Spack.

---------

Co-authored-by: Todd Gamblin <[email protected]>