# Manage Dependencies

PDM provides a bunch of useful commands to help manage your project and dependencies.
The following examples are run on Ubuntu 18.04, a few changes must be done if you are using Windows.

## Add dependencies

[`pdm add`](../reference/cli.md#add) can be followed by one or several dependencies, and the dependency specification is described in [PEP 508](https://www.python.org/dev/peps/pep-0508/).

Examples:

```bash
pdm add requests   # add requests
pdm add requests==2.25.1   # add requests with version constraint
pdm add requests[socks]   # add requests with extra dependency
pdm add "flask>=1.0" flask-sqlalchemy   # add multiple dependencies with different specifiers
```

PDM also allows extra dependency groups by providing `-G/--group <name>` option, and those dependencies will go to
`[project.optional-dependencies.<name>]` table in the project file, respectively.

You can reference other optional groups in `optional-dependencies`, even before the package is uploaded:

```toml
[project]
name = "foo"
version = "0.1.0"

[project.optional-dependencies]
socks = ["pysocks"]
jwt = ["pyjwt"]
all = ["foo[socks,jwt]"]
```

After that, dependencies and sub-dependencies will be resolved properly and installed for you, you can view `pdm.lock` to see the resolved result of all dependencies.

### Local dependencies

Local packages can be added with their paths. The path can be a file or a directory:

```bash
pdm add ./sub-package
pdm add ./first-1.0.0-py2.py3-none-any.whl
```

The paths MUST start with a `.`, otherwise it will be recognized as a normal named requirement. The local dependencies will be written to the `pyproject.toml` file with the URL format:

```toml
[project]
dependencies = [
    "sub-package @ file:///${PROJECT_ROOT}/sub-package",
    "first @ file:///${PROJECT_ROOT}/first-1.0.0-py2.py3-none-any.whl",
]
```

??? note "Using other build backends"
    If you are using `hatchling` instead of the pdm backend, the URLs would be as follows:

    ```
    sub-package @ {root:uri}/sub-package
    first @ {root:uri}/first-1.0.0-py2.py3-none-any.whl
    ```
    Other backends doesn't support encoding relative paths in the URL and will write the absolute path instead.

### URL dependencies

PDM also supports downloading and installing packages directly from a web address.

Examples:

```bash
# Install gzipped package from a plain URL
pdm add "https://github.com/numpy/numpy/releases/download/v1.20.0/numpy-1.20.0.tar.gz"
# Install wheel from a plain URL
pdm add "https://github.com/explosion/spacy-models/releases/download/en_core_web_trf-3.5.0/en_core_web_trf-3.5.0-py3-none-any.whl"
```

### VCS dependencies

You can also install from a git repository url or other version control systems. The following are supported:

- Git: `git`
- Mercurial: `hg`
- Subversion: `svn`
- Bazaar: `bzr`

The URL should be like: `{vcs}+{url}@{rev}`

Examples:

```bash
# Install pip repo on tag `22.0`
pdm add "git+https://github.com/pypa/pip.git@22.0"
# Provide credentials in the URL
pdm add "git+https://username:password@github.com/username/private-repo.git@master"
# Give a name to the dependency
pdm add "pip @ git+https://github.com/pypa/pip.git@22.0"
# Or use the #egg fragment
pdm add "git+https://github.com/pypa/pip.git@22.0#egg=pip"
# Install from a subdirectory
pdm add "git+https://github.com/owner/repo.git@master#egg=pkg&subdirectory=subpackage"
```

To use ssh scheme for git, just replace `https://` to `ssh://git@`

Example:

```bash
pdm add "wheel @ git+ssh://git@github.com/pypa/wheel.git@main"
```

### Hide credentials in the URL

You can hide the credentials in the URL by using the `${ENV_VAR}` variable syntax:

```toml
[project]
dependencies = [
  "mypackage @ git+http://${VCS_USER}:${VCS_PASSWD}@test.git.com/test/mypackage.git@master"
]
```

These variables will be read from the environment variables when installing the project.

### Add development only dependencies

+++ 1.5.0

PDM also supports defining groups of dependencies that are useful for development,
e.g. some for testing and others for linting. We usually don't want these dependencies to appear in the distribution's metadata
so using `optional-dependencies` is probably not a good idea. We can define them as development dependencies:

```bash
pdm add -dG test pytest
```

This will result in a pyproject.toml as following:

```toml
[dependency-groups]
test = ["pytest"]
```

You can have several groups of development only dependencies. Unlike `optional-dependencies`, they won't appear in the package distribution metadata such as `PKG-INFO` or `METADATA`.
The package index won't be aware of these dependencies. The schema is similar to that of `optional-dependencies`, except that it is in `tool.pdm` table.

```toml
[dependency-groups]
lint = [
    "flake8",
    "black"
]
test = ["pytest", "pytest-cov"]
doc = ["mkdocs"]
```

For backward-compatibility, if only `-d` or `--dev` is specified, dependencies will go to `dev` group under `[dependency-groups]` by default.

!!! NOTE
    The same group name MUST NOT appear in both `[dependency-groups]` and `[project.optional-dependencies]`.

### Editable dependencies

**Local directories** and **VCS dependencies** can be installed in [editable mode](https://pip.pypa.io/en/stable/cli/pip_install/#editable-installs). If you are familiar with `pip`, it is just like `pip install -e <package>`. **Editable packages are allowed only in development dependencies**:

!!! NOTE
    Editable installs are only allowed in the `dev` dependency group. Other groups, including the default, will fail with a `[PdmUsageError]`.

```bash
# A relative path to the directory
pdm add -e ./sub-package --dev
# A file URL to a local directory
pdm add -e file:///path/to/sub-package --dev
# A VCS URL
pdm add -e git+https://github.com/pallets/click.git@main#egg=click --dev
```

### Save version specifiers

If the package is given without a version specifier like `pdm add requests`.
PDM provides three different behaviors of what version specifier is saved for the dependency,
which is given by `--save-<strategy>`(Assume `2.21.0` is the latest version that can be found for the dependency):

- `minimum`: Save the minimum version specifier: `>=2.21.0` (default).
- `compatible`: Save the compatible version specifier: `>=2.21.0,<3.0.0`.
- `exact`: Save the exact version specifier: `==2.21.0`.
- `wildcard`: Don't constrain version and leave the specifier to be wildcard: `*`.

### Add prereleases

One can give `--pre/--prerelease` option to [`pdm add`](../reference/cli.md#add) so that prereleases are allowed to be pinned for the given packages.

## Update existing dependencies

To update all dependencies in the lock file:

```bash
pdm update
```

To update the specified package(s):

```bash
pdm update requests
```

To update multiple groups of dependencies:

```bash
pdm update -G security -G http
```

Or using comma-separated list:

```bash
pdm update -G "security,http"
```

To update a given package in the specified group:

```bash
pdm update -G security cryptography
```

If the group is not given, PDM will search for the requirement in the default dependencies set and raises an error if none is found.

To update packages in development dependencies:

```bash
# Update all default + dev-dependencies
pdm update -d
# Update a package in the specified group of dev-dependencies
pdm update -dG test pytest
```

### About update strategy

Similarly, PDM also provides 3 different behaviors of updating dependencies and sub-dependencies，
which is given by `--update-<strategy>` option:

- `reuse`: Keep all locked dependencies except for those given in the command line (default).
- `reuse-installed`: Try to reuse the versions installed in the working set. **This will also affect the packages requested in the command line**.
- `eager`: Try to lock a newer version of the packages in command line and their recursive sub-dependencies and keep other dependencies as they are.
- `all`: Update all dependencies and sub-dependencies.

### Update packages to the versions that break the version specifiers

One can give `-u/--unconstrained` to tell PDM to ignore the version specifiers in the `pyproject.toml`.
This works similarly to the `yarn upgrade -L/--latest` command. Besides,
[`pdm update`](../reference/cli.md#update_2) also supports the `--pre/--prerelease` option.

## Remove existing dependencies

To remove existing dependencies from project file and the library directory:

```bash
# Remove requests from the default dependencies
pdm remove requests
# Remove h11 from the 'web' group of optional-dependencies
pdm remove -G web h11
# Remove pytest-cov from the `test` group of dependency-groups
pdm remove -dG test pytest-cov
```

## List outdated packages and the latest versions

+++ 2.13.0

To list outdated packages and the latest versions:

```bash
pdm outdated
```

You can pass glob patterns to filter the packages to show:

```bash
pdm outdated requests* flask*
```

## Select a subset of dependency groups to install

Say we have a project with following dependencies:

```toml
[project]  # This is production dependencies
dependencies = ["requests"]

[project.optional-dependencies]  # This is optional dependencies
extra1 = ["flask"]
extra2 = ["django"]

[dependency-groups]  # This is dev dependencies
dev1 = ["pytest"]
dev2 = ["mkdocs"]
```

| Command                         | What it does                                                         | Comments                  |
| ------------------------------- | -------------------------------------------------------------------- | ------------------------- |
| `pdm install`                   | install all groups locked in the lockfile                            |                           |
| `pdm install -G extra1`         | install prod deps, dev deps, and "extra1" optional group             |                           |
| `pdm install -G dev1`           | install prod deps and only "dev1" dev group                          |                           |
| `pdm install -G:all`            | install prod deps, dev deps and "extra1", "extra2" optional groups   |                           |
| `pdm install -G extra1 -G dev1` | install prod deps, "extra1" optional group and only "dev1" dev group |                           |
| `pdm install --prod`            | install prod only                                                    |                           |
| `pdm install --prod -G extra1`  | install prod deps and "extra1" optional                              |                           |
| `pdm install --prod -G dev1`    | Fail, `--prod` can't be given with dev dependencies                  | Leave the `--prod` option |

**All** development dependencies are included as long as `--prod` is not passed and `-G` doesn't specify any dev groups.

Besides, if you don't want the root project to be installed, add `--no-self` option, and `--no-editable` can be used when you want all packages to be installed in non-editable versions.

You may also use the pdm lock command with these options to lock only the specified groups, which will be recorded in the `[metadata]` table of the lock file. If no `--group/--prod/--dev/--no-default` option is specified, `pdm sync` and `pdm update` will operate using the groups in the lockfile. However, if any groups that are not included in the lockfile are given as arguments to the commands, PDM will raise an error.

## Dependency Overrides

If none of versions of a specific package doesn't meet all the constraints, the resolution will fail. In this case, you can tell the resolver to use a specific version of the package with dependency overrides.

Overrides are a useful last resort for cases in which the user knows that a dependency is compatible with a newer version of a package than the package declares, but the package has not yet been updated to declare that compatibility.

For example, if a transitive dependency declares `pydantic>=1.0,<2.0`, but the user knows that the package is compatible with `pydantic>=2.0`, the user can override the declared dependency with `pydantic>=2.0,<3` to allow the resolver to continue.

In PDM, there are two ways to specify overrides:

### In the project file

+++ 1.12.0

You can specify the overrides in the `pyproject.toml` file, under the `[tool.pdm.resolution.overrides]` table:

```toml
[tool.pdm.resolution.overrides]
asgiref = "3.2.10"  # exact version
urllib3 = ">=1.26.2"  # version range
pytz = "https://mypypi.org/packages/pytz-2020.9-py3-none-any.whl"  # absolute URL
```

Each entry in the table is a package name and a version specifier. The version specifier can be a version range, an exact version, or an absolute URL.

### Via CLI option

+++ 2.17.0

PDM also supports reading dependency overrides from a requirements file. The file works similarly to the constraint file in pip(`--constraint constraints.txt`), and the syntax is the same as the requirements file:

```
requests==2.20.0
django==1.11.8
certifi==2018.11.17
chardet==3.0.4
idna==2.7
pytz==2019.3
urllib3==1.23
```

Override files serve as an easy way to store the dependencies in a centralized location that can be shared by multiple projects in your organization.

You can pass the constraint file to various PDM commands that would perform a resolution, such as [`pdm install`](../reference/cli.md#install), [`pdm lock`](../reference/cli.md#lock), [`pdm add`](../reference/cli.md#add), etc.

```bash
pdm lock --override constraints.txt
```

This option can be supplied multiple times.

Override files can also be served via a URL, e.g. `--override http://example.com/constraints.txt`, so that your organization can store and serve them in a remote server.

## Show what packages are installed

Similar to `pip list`, you can list all packages installed in the packages directory:

```bash
pdm list
```

### Include and exclude groups

By default, all packages installed in the working set will be listed. You can specify which groups to be listed
by `--include/--exclude` options, and `include` has a higher priority than `exclude`.

```bash
pdm list --include dev
pdm list --exclude test
```

There is a special group `:sub`, when included, all transitive dependencies will also be shown. It is included by default.

You can also pass `--resolve` to `pdm list`, which will show the packages resolved in `pdm.lock`, rather than installed in the working set.

### Change the output fields and format

By default, name, version and location will be shown in the list output, you can view more fields or specify the order of fields by `--fields` option:

```bash
pdm list --fields name,licenses,version
```

For all supported fields, please refer to the [CLI reference](../reference/cli.md#list_1).

Also, you can specify the output format other than the default table output. The supported formats and options are `--csv`, `--json`, `--markdown` and `--freeze`.

### Show the dependency tree

Or show a dependency tree by:

```bash
$ pdm list --tree
tempenv 0.0.0
└── click 7.0 [ required: <7.0.0,>=6.7 ]
black 19.10b0
├── appdirs 1.4.3 [ required: Any ]
├── attrs 19.3.0 [ required: >=18.1.0 ]
├── click 7.0 [ required: >=6.5 ]
├── pathspec 0.7.0 [ required: <1,>=0.6 ]
├── regex 2020.2.20 [ required: Any ]
├── toml 0.10.0 [ required: >=0.9.4 ]
└── typed-ast 1.4.1 [ required: >=1.4.0 ]
bump2version 1.0.0
```

Note that `--fields` option doesn't work with `--tree`.

### Filter packages by patterns

You can also limit the packages to show by passing the patterns to `pdm list`:

```bash
pdm list flask-* requests-*
```

??? warning "Be careful with the shell expansion"
    In most shells, the wildcard `*` will be expanded if there are matching files under the current directory.
    To avoid getting unexpected results, you can wrap the patterns with single quotes: `pdm list 'flask-*' 'requests-*'`.

In `--tree` mode, only the subtree of the matched packages will be displayed. This can be used to achieve the same purpose as `pnpm why`, which is to show why a specific package is required.

```bash
$ pdm list --tree --reverse certifi
certifi 2023.7.22
└── requests 2.31.0 [ requires: >=2017.4.17 ]
    └── cachecontrol[filecache] 0.13.1 [ requires: >=2.16.0 ]
```

## Manage global project

Sometimes users may want to keep track of the dependencies of global Python interpreter as well.
It is easy to do so with PDM, via `-g/--global` option which is supported by most subcommands.

If the option is passed, `<CONFIG_ROOT>/global-project` will be used as the project directory, which is
almost the same as normal project except that `pyproject.toml` will be created automatically for you
and it doesn't support build features. The idea is taken from Haskell's [stack](https://docs.haskellstack.org).

However, unlike `stack`, by default, PDM won't use global project automatically if a local project is not found.
Users should pass `-g/--global` explicitly to activate it, since it is not very pleasing if packages go to a wrong place.
But PDM also leave the decision to users, just set the config `global_project.fallback` to `true`.

By default, when `pdm` uses global project implicitly the following message is printed: `Project is not found, fallback to the global project`.
To disable this message set the config `global_project.fallback_verbose` to `false`.

If you want global project to track another project file other than `<CONFIG_ROOT>/global-project`,
you can provide the project path via `-p/--project <path>` option.
Especially if you pass `--global --project .`,
PDM will install the dependencies of the current project into the global Python.

!!! warning
    Be careful with `remove` and `sync --clean/--pure` commands when global project is used, because it may remove packages installed in your system Python.
