3 This document explains how Cargo’s configuration system works, as well as
4 available keys or configuration. For configuration of a package through its
5 manifest, see the [manifest format](manifest.md).
7 ### Hierarchical structure
9 Cargo allows local configuration for a particular package as well as global
10 configuration. It looks for configuration files in the current directory and
11 all parent directories. If, for example, Cargo were invoked in
12 `/projects/foo/bar/baz`, then the following configuration files would be
13 probed for and unified in this order:
15 * `/projects/foo/bar/baz/.cargo/config.toml`
16 * `/projects/foo/bar/.cargo/config.toml`
17 * `/projects/foo/.cargo/config.toml`
18 * `/projects/.cargo/config.toml`
19 * `/.cargo/config.toml`
20 * `$CARGO_HOME/config.toml` which defaults to:
21 * Windows: `%USERPROFILE%\.cargo\config.toml`
22 * Unix: `$HOME/.cargo/config.toml`
24 With this structure, you can specify configuration per-package, and even
25 possibly check it into version control. You can also specify personal defaults
26 with a configuration file in your home directory.
28 If a key is specified in multiple config files, the values will get merged
29 together. Numbers, strings, and booleans will use the value in the deeper
30 config directory taking precedence over ancestor directories, where the
31 home directory is the lowest priority. Arrays will be joined together.
33 At present, when being invoked from a workspace, Cargo does not read config
34 files from crates within the workspace. i.e. if a workspace has two crates in
35 it, named `/projects/foo/bar/baz/mylib` and `/projects/foo/bar/baz/mybin`, and
36 there are Cargo configs at `/projects/foo/bar/baz/mylib/.cargo/config.toml`
37 and `/projects/foo/bar/baz/mybin/.cargo/config.toml`, Cargo does not read
38 those configuration files if it is invoked from the workspace root
39 (`/projects/foo/bar/baz/`).
41 > **Note:** Cargo also reads config files without the `.toml` extension, such as
42 > `.cargo/config`. Support for the `.toml` extension was added in version 1.39
43 > and is the preferred form. If both files exist, Cargo will use the file
44 > without the extension.
46 ### Configuration format
48 Configuration files are written in the [TOML format][toml] (like the
49 manifest), with simple key-value pairs inside of sections (tables). The
50 following is a quick overview of all settings, with detailed descriptions
54 paths = ["/path/to/override"] # path dependency overrides
56 [alias] # command aliases
62 space_example = ["run", "--release", "--", "\"command list\""]
65 jobs = 1 # number of parallel jobs, defaults to # of CPUs
66 rustc = "rustc" # the rust compiler tool
67 rustc-wrapper = "…" # run this wrapper instead of `rustc`
68 rustc-workspace-wrapper = "…" # run this wrapper instead of `rustc` for workspace members
69 rustdoc = "rustdoc" # the doc generator tool
70 target = "triple" # build for the target triple (ignored by `cargo install`)
71 target-dir = "target" # path of where to place all generated artifacts
72 rustflags = ["…", "…"] # custom flags to pass to all compiler invocations
73 rustdocflags = ["…", "…"] # custom flags to pass to rustdoc
74 incremental = true # whether or not to enable incremental compilation
75 dep-info-basedir = "…" # path for the base directory for targets in depfiles
78 browser = "chromium" # browser to use with `cargo doc --open`,
79 # overrides the `BROWSER` environment variable
82 # Set ENV_VAR_NAME=value for any process run by Cargo
83 ENV_VAR_NAME = "value"
84 # Set even if already present in environment
85 ENV_VAR_NAME_2 = { value = "value", force = true }
86 # Value is relative to .cargo directory containing `config.toml`, make absolute
87 ENV_VAR_NAME_3 = { value = "relative/path", relative = true }
89 [future-incompat-report]
90 frequency = 'always' # when to display a notification about a future incompat report
93 vcs = "none" # VCS to use ('git', 'hg', 'pijul', 'fossil', 'none')
96 debug = false # HTTP debugging
97 proxy = "host:port" # HTTP proxy in libcurl format
98 ssl-version = "tlsv1.3" # TLS version to use
99 ssl-version.max = "tlsv1.3" # maximum TLS version
100 ssl-version.min = "tlsv1.1" # minimum TLS version
101 timeout = 30 # timeout for each HTTP request, in seconds
102 low-speed-limit = 10 # network timeout threshold (bytes/sec)
103 cainfo = "cert.pem" # path to Certificate Authority (CA) bundle
104 check-revoke = true # check for SSL certificate revocation
105 multiplexing = true # HTTP/2 multiplexing
106 user-agent = "…" # the user-agent header
109 root = "/some/path" # `cargo install` destination directory
112 retry = 2 # network retries
113 git-fetch-with-cli = true # use the `git` executable for git operations
114 offline = true # do not access the network
117 # Same keys as for [patch] in Cargo.toml
119 [profile.<name>] # Modify profile settings via config.
120 opt-level = 0 # Optimization level.
121 debug = true # Include debug info.
122 split-debuginfo = '...' # Debug info splitting behavior.
123 debug-assertions = true # Enables debug assertions.
124 overflow-checks = true # Enables runtime integer overflow checks.
125 lto = false # Sets link-time optimization.
126 panic = 'unwind' # The panic strategy.
127 incremental = true # Incremental compilation.
128 codegen-units = 16 # Number of code generation units.
129 rpath = false # Sets the rpath linking option.
130 [profile.<name>.build-override] # Overrides build-script settings.
131 # Same keys for a normal profile.
132 [profile.<name>.package.<name>] # Override profile for a package.
133 # Same keys for a normal profile (minus `panic`, `lto`, and `rpath`).
135 [registries.<name>] # registries other than crates.io
136 index = "…" # URL of the registry index
137 token = "…" # authentication token for the registry
140 default = "…" # name of the default registry
141 token = "…" # authentication token for crates.io
143 [source.<name>] # source definition and replacement
144 replace-with = "…" # replace this source with the given named source
145 directory = "…" # path to a directory source
146 registry = "…" # URL to a registry source
147 local-registry = "…" # path to a local registry source
148 git = "…" # URL of a git repository source
149 branch = "…" # branch name for the git repository
150 tag = "…" # tag name for the git repository
151 rev = "…" # revision for the git repository
154 linker = "…" # linker to use
155 runner = "…" # wrapper to run executables
156 rustflags = ["…", "…"] # custom flags for `rustc`
159 runner = "…" # wrapper to run executables
160 rustflags = ["…", "…"] # custom flags for `rustc`
162 [target.<triple>.<links>] # `links` build script override
163 rustc-link-lib = ["foo"]
164 rustc-link-search = ["/path/to/foo"]
165 rustc-flags = ["-L", "/some/path"]
166 rustc-cfg = ['key="value"']
167 rustc-env = {key = "value"}
168 rustc-cdylib-link-arg = ["…"]
169 metadata_key1 = "value"
170 metadata_key2 = "value"
173 quiet = false # whether cargo output is quiet
174 verbose = false # whether cargo provides verbose output
175 color = 'auto' # whether cargo colorizes output
176 progress.when = 'auto' # whether cargo shows progress bar
177 progress.width = 80 # width of progress bar
180 ### Environment variables
182 Cargo can also be configured through environment variables in addition to the
183 TOML configuration files. For each configuration key of the form `foo.bar` the
184 environment variable `CARGO_FOO_BAR` can also be used to define the value.
185 Keys are converted to uppercase, dots and dashes are converted to underscores.
186 For example the `target.x86_64-unknown-linux-gnu.runner` key can also be
187 defined by the `CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER` environment
190 Environment variables will take precedence over TOML configuration files.
191 Currently only integer, boolean, string and some array values are supported to
192 be defined by environment variables. Descriptions below indicate which keys
193 support environment variables.
195 In addition to the system above, Cargo recognizes a few other specific
196 [environment variables][env].
198 ### Command-line overrides
200 Cargo also accepts arbitrary configuration overrides through the
201 `--config` command-line option. The argument should be in TOML syntax of
205 cargo --config net.git-fetch-with-cli=true fetch
208 The `--config` option may be specified multiple times, in which case the
209 values are merged in left-to-right order, using the same merging logic
210 that is used when multiple configuration files apply. Configuration
211 values specified this way take precedence over environment variables,
212 which take precedence over configuration files.
214 Some examples of what it looks like using Bourne shell syntax:
217 # Most shells will require escaping.
218 cargo --config http.proxy=\"http://example.com\" …
220 # Spaces may be used.
221 cargo --config "net.git-fetch-with-cli = true" …
223 # TOML array example. Single quotes make it easier to read and write.
224 cargo --config 'build.rustdocflags = ["--html-in-header", "header.html"]' …
226 # Example of a complex TOML key.
227 cargo --config "target.'cfg(all(target_arch = \"arm\", target_os = \"none\"))'.runner = 'my-runner'" …
229 # Example of overriding a profile setting.
230 cargo --config profile.dev.package.image.opt-level=3 …
233 The `--config` option can also be used to pass paths to extra
234 configuration files that Cargo should use for a specific invocation.
235 Options from configuration files loaded this way follow the same
236 precedence rules as other options specified directly with `--config`.
238 ### Config-relative paths
240 Paths in config files may be absolute, relative, or a bare name without any
241 path separators. Paths for executables without a path separator will use the
242 `PATH` environment variable to search for the executable. Paths for
243 non-executables will be relative to where the config value is defined. For
244 config files, that is relative to the parent directory of the `.cargo`
245 directory where the value was defined. For environment variables it is
246 relative to the current working directory.
249 # Relative path examples.
251 [target.x86_64-unknown-linux-gnu]
252 runner = "foo" # Searches `PATH` for `foo`.
254 [source.vendored-sources]
255 # Directory is relative to the parent where `.cargo/config.toml` is located.
256 # For example, `/my/project/.cargo/config.toml` would result in `/my/project/vendor`.
260 ### Executable paths with arguments
262 Some Cargo commands invoke external programs, which can be configured as a path
263 and some number of arguments.
265 The value may be an array of strings like `['/path/to/program', 'somearg']` or
266 a space-separated string like `'/path/to/program somearg'`. If the path to the
267 executable contains a space, the list form must be used.
269 If Cargo is passing other arguments to the program such as a path to open or
270 run, they will be passed after the last specified argument in the value of an
271 option of this format. If the specified program does not have path separators,
272 Cargo will search `PATH` for its executable.
276 Configuration values with sensitive information are stored in the
277 `$CARGO_HOME/credentials.toml` file. This file is automatically created and updated
278 by [`cargo login`]. It follows the same format as Cargo config files.
282 token = "…" # Access token for crates.io
285 token = "…" # Access token for the named registry
288 Tokens are used by some Cargo commands such as [`cargo publish`] for
289 authenticating with remote registries. Care should be taken to protect the
290 tokens and to keep them secret.
292 As with most other config values, tokens may be specified with environment
293 variables. The token for [crates.io] may be specified with the
294 `CARGO_REGISTRY_TOKEN` environment variable. Tokens for other registries may
295 be specified with environment variables of the form
296 `CARGO_REGISTRIES_<name>_TOKEN` where `<name>` is the name of the registry in
299 ### Configuration keys
301 This section documents all configuration keys. The description for keys with
302 variable parts are annotated with angled brackets like `target.<triple>` where
303 the `<triple>` part can be any target triple like
304 `target.x86_64-pc-windows-msvc`.
307 * Type: array of strings (paths)
309 * Environment: not supported
311 An array of paths to local packages which are to be used as overrides for
312 dependencies. For more information see the [Overriding Dependencies
313 guide](overriding-dependencies.md#paths-overrides).
316 * Type: string or array of strings
318 * Environment: `CARGO_ALIAS_<name>`
320 The `[alias]` table defines CLI command aliases. For example, running `cargo
321 b` is an alias for running `cargo build`. Each key in the table is the
322 subcommand, and the value is the actual command to run. The value may be an
323 array of strings, where the first element is the command and the following are
324 arguments. It may also be a string, which will be split on spaces into
325 subcommand and arguments. The following aliases are built-in to Cargo:
336 Aliases are not allowed to redefine existing built-in commands.
340 The `[build]` table controls build-time operations and compiler settings.
344 * Default: number of logical CPUs
345 * Environment: `CARGO_BUILD_JOBS`
347 Sets the maximum number of compiler processes to run in parallel.
349 Can be overridden with the `--jobs` CLI option.
352 * Type: string (program path)
354 * Environment: `CARGO_BUILD_RUSTC` or `RUSTC`
356 Sets the executable to use for `rustc`.
358 ##### `build.rustc-wrapper`
359 * Type: string (program path)
361 * Environment: `CARGO_BUILD_RUSTC_WRAPPER` or `RUSTC_WRAPPER`
363 Sets a wrapper to execute instead of `rustc`. The first argument passed to the
364 wrapper is the path to the actual `rustc`.
366 ##### `build.rustc-workspace-wrapper`
367 * Type: string (program path)
369 * Environment: `CARGO_BUILD_RUSTC_WORKSPACE_WRAPPER` or `RUSTC_WORKSPACE_WRAPPER`
371 Sets a wrapper to execute instead of `rustc`, for workspace members only.
372 The first argument passed to the wrapper is the path to the actual `rustc`.
373 It affects the filename hash so that artifacts produced by the wrapper are cached separately.
375 ##### `build.rustdoc`
376 * Type: string (program path)
378 * Environment: `CARGO_BUILD_RUSTDOC` or `RUSTDOC`
380 Sets the executable to use for `rustdoc`.
383 * Type: string or array of strings
384 * Default: host platform
385 * Environment: `CARGO_BUILD_TARGET`
387 The default target platform triples to compile to.
389 This allows passing either a string or an array of strings. Each string value
390 is a target platform triple. The selected build targets will be built for each
391 of the selected architectures.
393 The string value may also be a relative path to a `.json` target spec file.
395 Can be overridden with the `--target` CLI option.
399 target = ["x86_64-unknown-linux-gnu", "i686-unknown-linux-gnu"]
402 ##### `build.target-dir`
403 * Type: string (path)
405 * Environment: `CARGO_BUILD_TARGET_DIR` or `CARGO_TARGET_DIR`
407 The path to where all compiler output is placed. The default if not specified
408 is a directory named `target` located at the root of the workspace.
410 Can be overridden with the `--target-dir` CLI option.
412 ##### `build.rustflags`
413 * Type: string or array of strings
415 * Environment: `CARGO_BUILD_RUSTFLAGS` or `CARGO_ENCODED_RUSTFLAGS` or `RUSTFLAGS`
417 Extra command-line flags to pass to `rustc`. The value may be an array of
418 strings or a space-separated string.
420 There are four mutually exclusive sources of extra flags. They are checked in
421 order, with the first one being used:
423 1. `CARGO_ENCODED_RUSTFLAGS` environment variable.
424 2. `RUSTFLAGS` environment variable.
425 3. All matching `target.<triple>.rustflags` and `target.<cfg>.rustflags`
426 config entries joined together.
427 4. `build.rustflags` config value.
429 Additional flags may also be passed with the [`cargo rustc`] command.
431 If the `--target` flag (or [`build.target`](#buildtarget)) is used, then the
432 flags will only be passed to the compiler for the target. Things being built
433 for the host, such as build scripts or proc macros, will not receive the args.
434 Without `--target`, the flags will be passed to all compiler invocations
435 (including build scripts and proc macros) because dependencies are shared. If
436 you have args that you do not want to pass to build scripts or proc macros and
437 are building for the host, pass `--target` with the host triple.
439 It is not recommended to pass in flags that Cargo itself usually manages. For
440 example, the flags driven by [profiles](profiles.md) are best handled by setting the
441 appropriate profile setting.
443 > **Caution**: Due to the low-level nature of passing flags directly to the
444 > compiler, this may cause a conflict with future versions of Cargo which may
445 > issue the same or similar flags on its own which may interfere with the
446 > flags you specify. This is an area where Cargo may not always be backwards
449 ##### `build.rustdocflags`
450 * Type: string or array of strings
452 * Environment: `CARGO_BUILD_RUSTDOCFLAGS` or `CARGO_ENCODED_RUSTDOCFLAGS` or `RUSTDOCFLAGS`
454 Extra command-line flags to pass to `rustdoc`. The value may be an array of
455 strings or a space-separated string.
457 There are three mutually exclusive sources of extra flags. They are checked in
458 order, with the first one being used:
460 1. `CARGO_ENCODED_RUSTDOCFLAGS` environment variable.
461 2. `RUSTDOCFLAGS` environment variable.
462 3. `build.rustdocflags` config value.
464 Additional flags may also be passed with the [`cargo rustdoc`] command.
466 ##### `build.incremental`
468 * Default: from profile
469 * Environment: `CARGO_BUILD_INCREMENTAL` or `CARGO_INCREMENTAL`
471 Whether or not to perform [incremental compilation]. The default if not set is
472 to use the value from the [profile](profiles.md#incremental). Otherwise this overrides the setting of
475 The `CARGO_INCREMENTAL` environment variable can be set to `1` to force enable
476 incremental compilation for all profiles, or `0` to disable it. This env var
477 overrides the config setting.
479 ##### `build.dep-info-basedir`
480 * Type: string (path)
482 * Environment: `CARGO_BUILD_DEP_INFO_BASEDIR`
484 Strips the given path prefix from [dep
485 info](../guide/build-cache.md#dep-info-files) file paths. This config setting
486 is intended to convert absolute paths to relative paths for tools that require
489 The setting itself is a config-relative path. So, for example, a value of
490 `"."` would strip all paths starting with the parent directory of the `.cargo`
493 ##### `build.pipelining`
495 This option is deprecated and unused. Cargo always has pipelining enabled.
499 The `[doc]` table defines options for the [`cargo doc`] command.
503 * Type: string or array of strings ([program path with args])
504 * Default: `BROWSER` environment variable, or, if that is missing,
505 opening the link in a system specific way
507 This option sets the browser to be used by [`cargo doc`], overriding the
508 `BROWSER` environment variable when opening documentation with the `--open`
513 The `[cargo-new]` table defines defaults for the [`cargo new`] command.
515 ##### `cargo-new.name`
517 This option is deprecated and unused.
519 ##### `cargo-new.email`
521 This option is deprecated and unused.
523 ##### `cargo-new.vcs`
525 * Default: "git" or "none"
526 * Environment: `CARGO_CARGO_NEW_VCS`
528 Specifies the source control system to use for initializing a new repository.
529 Valid values are `git`, `hg` (for Mercurial), `pijul`, `fossil` or `none` to
530 disable this behavior. Defaults to `git`, or `none` if already inside a VCS
531 repository. Can be overridden with the `--vcs` CLI option.
535 The `[env]` section allows you to set additional environment variables for
536 build scripts, rustc invocations, `cargo run` and `cargo build`.
540 OPENSSL_DIR = "/opt/openssl"
543 By default, the variables specified will not override values that already exist
544 in the environment. This behavior can be changed by setting the `force` flag.
546 Setting the `relative` flag evaluates the value as a config-relative path that
547 is relative to the parent directory of the `.cargo` directory that contains the
548 `config.toml` file. The value of the environment variable will be the full
553 TMPDIR = { value = "/home/tmp", force = true }
554 OPENSSL_DIR = { value = "vendor/openssl", relative = true }
557 ### `[future-incompat-report]`
559 The `[future-incompat-report]` table controls setting for [future incompat reporting](future-incompat-report.md)
561 #### `future-incompat-report.frequency`
564 * Environment: `CARGO_FUTURE_INCOMPAT_REPORT_FREQUENCY`
566 Controls how often we display a notification to the terminal when a future incompat report is available. Possible values:
568 * `always` (default): Always display a notification when a command (e.g. `cargo build`) produces a future incompat report
569 * `never`: Never display a notification
573 The `[http]` table defines settings for HTTP behavior. This includes fetching
574 crate dependencies and accessing remote git repositories.
579 * Environment: `CARGO_HTTP_DEBUG`
581 If `true`, enables debugging of HTTP requests. The debug information can be
582 seen by setting the `CARGO_LOG=cargo::ops::registry=debug` environment
583 variable (or use `trace` for even more information).
585 Be wary when posting logs from this output in a public location. The output
586 may include headers with authentication tokens which you don't want to leak!
587 Be sure to review logs before posting them.
592 * Environment: `CARGO_HTTP_PROXY` or `HTTPS_PROXY` or `https_proxy` or `http_proxy`
594 Sets an HTTP and HTTPS proxy to use. The format is in [libcurl format] as in
595 `[protocol://]host[:port]`. If not set, Cargo will also check the `http.proxy`
596 setting in your global git configuration. If none of those are set, the
597 `HTTPS_PROXY` or `https_proxy` environment variables set the proxy for HTTPS
598 requests, and `http_proxy` sets it for HTTP requests.
603 * Environment: `CARGO_HTTP_TIMEOUT` or `HTTP_TIMEOUT`
605 Sets the timeout for each HTTP request, in seconds.
608 * Type: string (path)
610 * Environment: `CARGO_HTTP_CAINFO`
612 Path to a Certificate Authority (CA) bundle file, used to verify TLS
613 certificates. If not specified, Cargo attempts to use the system certificates.
615 ##### `http.check-revoke`
617 * Default: true (Windows) false (all others)
618 * Environment: `CARGO_HTTP_CHECK_REVOKE`
620 This determines whether or not TLS certificate revocation checks should be
621 performed. This only works on Windows.
623 ##### `http.ssl-version`
624 * Type: string or min/max table
626 * Environment: `CARGO_HTTP_SSL_VERSION`
628 This sets the minimum TLS version to use. It takes a string, with one of the
629 possible values of "default", "tlsv1", "tlsv1.0", "tlsv1.1", "tlsv1.2", or
632 This may alternatively take a table with two keys, `min` and `max`, which each
633 take a string value of the same kind that specifies the minimum and maximum
634 range of TLS versions to use.
636 The default is a minimum version of "tlsv1.0" and a max of the newest version
637 supported on your platform, typically "tlsv1.3".
639 ##### `http.low-speed-limit`
642 * Environment: `CARGO_HTTP_LOW_SPEED_LIMIT`
644 This setting controls timeout behavior for slow connections. If the average
645 transfer speed in bytes per second is below the given value for
646 [`http.timeout`](#httptimeout) seconds (default 30 seconds), then the
647 connection is considered too slow and Cargo will abort and retry.
649 ##### `http.multiplexing`
652 * Environment: `CARGO_HTTP_MULTIPLEXING`
654 When `true`, Cargo will attempt to use the HTTP2 protocol with multiplexing.
655 This allows multiple requests to use the same connection, usually improving
656 performance when fetching multiple files. If `false`, Cargo will use HTTP 1.1
659 ##### `http.user-agent`
661 * Default: Cargo's version
662 * Environment: `CARGO_HTTP_USER_AGENT`
664 Specifies a custom user-agent header to use. The default if not specified is a
665 string that includes Cargo's version.
669 The `[install]` table defines defaults for the [`cargo install`] command.
672 * Type: string (path)
673 * Default: Cargo's home directory
674 * Environment: `CARGO_INSTALL_ROOT`
676 Sets the path to the root directory for installing executables for [`cargo
677 install`]. Executables go into a `bin` directory underneath the root.
679 To track information of installed executables, some extra files, such as
680 `.crates.toml` and `.crates2.json`, are also created under this root.
682 The default if not specified is Cargo's home directory (default `.cargo` in
683 your home directory).
685 Can be overridden with the `--root` command-line option.
689 The `[net]` table controls networking configuration.
694 * Environment: `CARGO_NET_RETRY`
696 Number of times to retry possibly spurious network errors.
698 ##### `net.git-fetch-with-cli`
701 * Environment: `CARGO_NET_GIT_FETCH_WITH_CLI`
703 If this is `true`, then Cargo will use the `git` executable to fetch registry
704 indexes and git dependencies. If `false`, then it uses a built-in `git`
707 Setting this to `true` can be helpful if you have special authentication
708 requirements that Cargo does not support. See [Git
709 Authentication](../appendix/git-authentication.md) for more information about
710 setting up git authentication.
715 * Environment: `CARGO_NET_OFFLINE`
717 If this is `true`, then Cargo will avoid accessing the network, and attempt to
718 proceed with locally cached data. If `false`, Cargo will access the network as
719 needed, and generate an error if it encounters a network error.
721 Can be overridden with the `--offline` command-line option.
725 Just as you can override dependencies using [`[patch]` in
726 `Cargo.toml`](overriding-dependencies.md#the-patch-section), you can
727 override them in the cargo configuration file to apply those patches to
728 any affected build. The format is identical to the one used in
731 Since `.cargo/config.toml` files are not usually checked into source
732 control, you should prefer patching using `Cargo.toml` where possible to
733 ensure that other developers can compile your crate in their own
734 environments. Patching through cargo configuration files is generally
735 only appropriate when the patch section is automatically generated by an
738 If a given dependency is patched both in a cargo configuration file and
739 a `Cargo.toml` file, the patch in the configuration file is used. If
740 multiple configuration files patch the same dependency, standard cargo
741 configuration merging is used, which prefers the value defined closest
742 to the current directory, with `$HOME/.cargo/config.toml` taking the
745 Relative `path` dependencies in such a `[patch]` section are resolved
746 relative to the configuration file they appear in.
750 The `[profile]` table can be used to globally change profile settings, and
751 override settings specified in `Cargo.toml`. It has the same syntax and
752 options as profiles specified in `Cargo.toml`. See the [Profiles chapter] for
753 details about the options.
755 [Profiles chapter]: profiles.md
757 ##### `[profile.<name>.build-override]`
758 * Environment: `CARGO_PROFILE_<name>_BUILD_OVERRIDE_<key>`
760 The build-override table overrides settings for build scripts, proc macros,
761 and their dependencies. It has the same keys as a normal profile. See the
762 [overrides section](profiles.md#overrides) for more details.
764 ##### `[profile.<name>.package.<name>]`
765 * Environment: not supported
767 The package table overrides settings for specific packages. It has the same
768 keys as a normal profile, minus the `panic`, `lto`, and `rpath` settings. See
769 the [overrides section](profiles.md#overrides) for more details.
771 ##### `profile.<name>.codegen-units`
773 * Default: See profile docs.
774 * Environment: `CARGO_PROFILE_<name>_CODEGEN_UNITS`
776 See [codegen-units](profiles.md#codegen-units).
778 ##### `profile.<name>.debug`
779 * Type: integer or boolean
780 * Default: See profile docs.
781 * Environment: `CARGO_PROFILE_<name>_DEBUG`
783 See [debug](profiles.md#debug).
785 ##### `profile.<name>.split-debuginfo`
787 * Default: See profile docs.
788 * Environment: `CARGO_PROFILE_<name>_SPLIT_DEBUGINFO`
790 See [split-debuginfo](profiles.md#split-debuginfo).
792 ##### `profile.<name>.debug-assertions`
794 * Default: See profile docs.
795 * Environment: `CARGO_PROFILE_<name>_DEBUG_ASSERTIONS`
797 See [debug-assertions](profiles.md#debug-assertions).
799 ##### `profile.<name>.incremental`
801 * Default: See profile docs.
802 * Environment: `CARGO_PROFILE_<name>_INCREMENTAL`
804 See [incremental](profiles.md#incremental).
806 ##### `profile.<name>.lto`
807 * Type: string or boolean
808 * Default: See profile docs.
809 * Environment: `CARGO_PROFILE_<name>_LTO`
811 See [lto](profiles.md#lto).
813 ##### `profile.<name>.overflow-checks`
815 * Default: See profile docs.
816 * Environment: `CARGO_PROFILE_<name>_OVERFLOW_CHECKS`
818 See [overflow-checks](profiles.md#overflow-checks).
820 ##### `profile.<name>.opt-level`
821 * Type: integer or string
822 * Default: See profile docs.
823 * Environment: `CARGO_PROFILE_<name>_OPT_LEVEL`
825 See [opt-level](profiles.md#opt-level).
827 ##### `profile.<name>.panic`
829 * default: See profile docs.
830 * Environment: `CARGO_PROFILE_<name>_PANIC`
832 See [panic](profiles.md#panic).
834 ##### `profile.<name>.rpath`
836 * default: See profile docs.
837 * Environment: `CARGO_PROFILE_<name>_RPATH`
839 See [rpath](profiles.md#rpath).
844 The `[registries]` table is used for specifying additional [registries]. It
845 consists of a sub-table for each named registry.
847 ##### `registries.<name>.index`
850 * Environment: `CARGO_REGISTRIES_<name>_INDEX`
852 Specifies the URL of the git index for the registry.
854 ##### `registries.<name>.token`
857 * Environment: `CARGO_REGISTRIES_<name>_TOKEN`
859 Specifies the authentication token for the given registry. This value should
860 only appear in the [credentials](#credentials) file. This is used for registry
861 commands like [`cargo publish`] that require authentication.
863 Can be overridden with the `--token` command-line option.
867 The `[registry]` table controls the default registry used when one is not
870 ##### `registry.index`
872 This value is no longer accepted and should not be used.
874 ##### `registry.default`
876 * Default: `"crates-io"`
877 * Environment: `CARGO_REGISTRY_DEFAULT`
879 The name of the registry (from the [`registries` table](#registries)) to use
880 by default for registry commands like [`cargo publish`].
882 Can be overridden with the `--registry` command-line option.
884 ##### `registry.token`
887 * Environment: `CARGO_REGISTRY_TOKEN`
889 Specifies the authentication token for [crates.io]. This value should only
890 appear in the [credentials](#credentials) file. This is used for registry
891 commands like [`cargo publish`] that require authentication.
893 Can be overridden with the `--token` command-line option.
897 The `[source]` table defines the registry sources available. See [Source
898 Replacement] for more information. It consists of a sub-table for each named
899 source. A source should only define one kind (directory, registry,
900 local-registry, or git).
902 ##### `source.<name>.replace-with`
905 * Environment: not supported
907 If set, replace this source with the given named source.
909 ##### `source.<name>.directory`
910 * Type: string (path)
912 * Environment: not supported
914 Sets the path to a directory to use as a directory source.
916 ##### `source.<name>.registry`
919 * Environment: not supported
921 Sets the URL to use for a registry source.
923 ##### `source.<name>.local-registry`
924 * Type: string (path)
926 * Environment: not supported
928 Sets the path to a directory to use as a local registry source.
930 ##### `source.<name>.git`
933 * Environment: not supported
935 Sets the URL to use for a git repository source.
937 ##### `source.<name>.branch`
940 * Environment: not supported
942 Sets the branch name to use for a git repository.
944 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
946 ##### `source.<name>.tag`
949 * Environment: not supported
951 Sets the tag name to use for a git repository.
953 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
955 ##### `source.<name>.rev`
958 * Environment: not supported
960 Sets the [revision] to use for a git repository.
962 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
967 The `[target]` table is used for specifying settings for specific platform
968 targets. It consists of a sub-table which is either a platform triple or a
969 [`cfg()` expression]. The given values will be used if the target platform
970 matches either the `<triple>` value or the `<cfg>` expression.
973 [target.thumbv7m-none-eabi]
974 linker = "arm-none-eabi-gcc"
975 runner = "my-emulator"
976 rustflags = ["…", "…"]
978 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
979 runner = "my-arm-wrapper"
980 rustflags = ["…", "…"]
983 `cfg` values come from those built-in to the compiler (run `rustc --print=cfg`
984 to view), values set by [build scripts], and extra `--cfg` flags passed to
985 `rustc` (such as those defined in `RUSTFLAGS`). Do not try to match on
986 `debug_assertions` or Cargo features like `feature="foo"`.
988 If using a target spec JSON file, the `<triple>` value is the filename stem.
989 For example `--target foo/bar.json` would match `[target.bar]`.
991 ##### `target.<triple>.ar`
993 This option is deprecated and unused.
995 ##### `target.<triple>.linker`
996 * Type: string (program path)
998 * Environment: `CARGO_TARGET_<triple>_LINKER`
1000 Specifies the linker which is passed to `rustc` (via [`-C linker`]) when the
1001 `<triple>` is being compiled for. By default, the linker is not overridden.
1003 ##### `target.<triple>.runner`
1004 * Type: string or array of strings ([program path with args])
1006 * Environment: `CARGO_TARGET_<triple>_RUNNER`
1008 If a runner is provided, executables for the target `<triple>` will be
1009 executed by invoking the specified runner with the actual executable passed as
1010 an argument. This applies to [`cargo run`], [`cargo test`] and [`cargo bench`]
1011 commands. By default, compiled executables are executed directly.
1013 ##### `target.<cfg>.runner`
1015 This is similar to the [target runner](#targettriplerunner), but using
1016 a [`cfg()` expression]. If both a `<triple>` and `<cfg>` runner match,
1017 the `<triple>` will take precedence. It is an error if more than one
1018 `<cfg>` runner matches the current target.
1020 ##### `target.<triple>.rustflags`
1021 * Type: string or array of strings
1023 * Environment: `CARGO_TARGET_<triple>_RUSTFLAGS`
1025 Passes a set of custom flags to the compiler for this `<triple>`. The value
1026 may be an array of strings or a space-separated string.
1028 See [`build.rustflags`](#buildrustflags) for more details on the different
1029 ways to specific extra flags.
1031 ##### `target.<cfg>.rustflags`
1033 This is similar to the [target rustflags](#targettriplerustflags), but
1034 using a [`cfg()` expression]. If several `<cfg>` and `<triple>` entries
1035 match the current target, the flags are joined together.
1037 ##### `target.<triple>.<links>`
1039 The links sub-table provides a way to [override a build script]. When
1040 specified, the build script for the given `links` library will not be
1041 run, and the given values will be used instead.
1044 [target.x86_64-unknown-linux-gnu.foo]
1045 rustc-link-lib = ["foo"]
1046 rustc-link-search = ["/path/to/foo"]
1047 rustc-flags = "-L /some/path"
1048 rustc-cfg = ['key="value"']
1049 rustc-env = {key = "value"}
1050 rustc-cdylib-link-arg = ["…"]
1051 metadata_key1 = "value"
1052 metadata_key2 = "value"
1057 The `[term]` table controls terminal output and interaction.
1062 * Environment: `CARGO_TERM_QUIET`
1064 Controls whether or not log messages are displayed by Cargo.
1066 Specifying the `--quiet` flag will override and force quiet output.
1067 Specifying the `--verbose` flag will override and disable quiet output.
1069 ##### `term.verbose`
1072 * Environment: `CARGO_TERM_VERBOSE`
1074 Controls whether or not extra detailed messages are displayed by Cargo.
1076 Specifying the `--quiet` flag will override and disable verbose output.
1077 Specifying the `--verbose` flag will override and force verbose output.
1082 * Environment: `CARGO_TERM_COLOR`
1084 Controls whether or not colored output is used in the terminal. Possible values:
1086 * `auto` (default): Automatically detect if color support is available on the
1088 * `always`: Always display colors.
1089 * `never`: Never display colors.
1091 Can be overridden with the `--color` command-line option.
1093 ##### `term.progress.when`
1096 * Environment: `CARGO_TERM_PROGRESS_WHEN`
1098 Controls whether or not progress bar is shown in the terminal. Possible values:
1100 * `auto` (default): Intelligently guess whether to show progress bar.
1101 * `always`: Always show progress bar.
1102 * `never`: Never show progress bar.
1104 ##### `term.progress.width`
1107 * Environment: `CARGO_TERM_PROGRESS_WIDTH`
1109 Sets the width for progress bar.
1111 [`cargo bench`]: ../commands/cargo-bench.md
1112 [`cargo login`]: ../commands/cargo-login.md
1113 [`cargo doc`]: ../commands/cargo-doc.md
1114 [`cargo new`]: ../commands/cargo-new.md
1115 [`cargo publish`]: ../commands/cargo-publish.md
1116 [`cargo run`]: ../commands/cargo-run.md
1117 [`cargo rustc`]: ../commands/cargo-rustc.md
1118 [`cargo test`]: ../commands/cargo-test.md
1119 [`cargo rustdoc`]: ../commands/cargo-rustdoc.md
1120 [`cargo install`]: ../commands/cargo-install.md
1121 [env]: environment-variables.md
1122 [`cfg()` expression]: ../../reference/conditional-compilation.html
1123 [build scripts]: build-scripts.md
1124 [`-C linker`]: ../../rustc/codegen-options/index.md#linker
1125 [override a build script]: build-scripts.md#overriding-build-scripts
1126 [toml]: https://toml.io/
1127 [incremental compilation]: profiles.md#incremental
1128 [program path with args]: #executable-paths-with-arguments
1129 [libcurl format]: https://everything.curl.dev/libcurl/proxies#proxy-types
1130 [source replacement]: source-replacement.md
1131 [revision]: https://git-scm.com/docs/gitrevisions
1132 [registries]: registries.md
1133 [crates.io]: https://crates.io/