In r-lib/cli: Helpers for Developing Command Line Interfaces

These are environment variables and options that users may set, to modify the behavior of cli.

Hyperlinks

cli uses ANSI escape sequences to create hyperlinks. Specifically, cli creates OSC 8 hyperlinks that have this syntax:

OSC 8 ; {OPTIONAL PARAMS } ; {URI} ST {LINK TEXT} OSC 8 ; ; ST

Under the hood, [style_hyperlink()] is the helper that forms these links, but it is more common to request them indirectly via inline markup (documented in help("links")).

R_CLI_HYPERLINK_MODE

Set to posix to force generating POSIX compatible ANSI hyperlinks. This is about the specific operating system command (OSC) and string terminator (ST) used in hyperlinks.

If not set, then RStudio compatible links are generated. This is a temporary crutch until RStudio handles POSIX hyperlinks correctly, and after that it will be removed.

cli.hyperlink option and R_CLI_HYPERLINKS env var

Set this option or env var to true, TRUE or True to tell cli that the terminal supports ANSI hyperlinks. Leave this configuration unset (or set to anything else) when there is no hyperlink support. Specifically, this configuration indicates the support for URL and file hyperlinks, requested via markup like {.href url} or {.file path/file}. (Below we describe the configuration that indicates support for even more specialized types of hyperlinks.)

The option cli.hyperlink takes precedence over the R_CLI_HYPERLINKS env var.

cli.hyperlink_* options and R_CLI_HYPERLINK_* env vars

cli supports a few special types of hyperlink that go beyond pointing to, e.g., a webpage or a file. These specialized hyperlinks cause R-specific actions to happen, such as executing a bit of R code or opening specific documentation.

Set the relevant option or env var to true, TRUE, or True to tell cli that the terminal is capable of implementing these specialized behaviours. Leave this configuration unset (or set to anything else) when there is no support for a specific type of hyperlink.

| Action | Example inline markup | Option | Env var | |-------------------|---------------------------------------------------------------------------------------|--------------------------|----------------------------| | Run R code | {.run testthat::snapshot_review()} | cli.hyperlink_run | R_CLI_HYPERLINK_RUN | | Open a help topic | {.fun stats::lm} {.topic tibble::tibble_options} {.help [{.fun lm}](stats::lm)} | cli.hyperlink_help | R_CLI_HYPERLINK_HELP | | Open a vignette | {.vignette tibble::types} | cli.hyperlink_vignette | R_CLI_HYPERLINK_VIGNETTE |

In all cases, the option takes priority over the corresponding env var.

cli.hyperlink_*_url_format options and R_CLI_HYPERLINK_*_URL_FORMAT env vars

Recall the overall structure of cli's hyperlinks:

OSC 8 ; {OPTIONAL PARAMS } ; {URI} ST {LINK TEXT} OSC 8 ; ; ST

The URI part has a default format for each type of hyperlink, but it is possible to provide a custom format via an option or an env var. If defined, the option takes priority over the env var.

| Action | Default URI format | Customize via option | Customize via env var | |-------------------|---------------------------|-------------------------------------|---------------------------------------| | Open a file | (see below) | cli.hyperlink_file_url_format | R_CLI_HYPERLINK_FILE_URL_FORMAT | | Run R code | x-r-run:{code} | cli.hyperlink_run_url_format | R_CLI_HYPERLINK_RUN_URL_FORMAT | | Open a help topic | x-r-help:{topic} | cli.hyperlink_help_url_format | R_CLI_HYPERLINK_HELP_URL_FORMAT | | Open a vignette | x-r-vignette:{vignette} | cli.hyperlink_vignette_url_format | R_CLI_HYPERLINK_VIGNETTE_URL_FORMAT |

A format must be a glue-like template with the relevant placeholder in curly braces (code, topic or vignette).

Here's an example of a custom URI format for runnable code, which is useful in an integrated Positron terminal:

positron://positron.positron-r/cli?command=x-r-run:{code}

(For backwards compatibility with older versions of RStudio, in some contexts, a legacy format is used, e.g. ide:run:{code}.)

The default handling for file hyperlinks is geared towards the expectations of RStudio and can't really be expressed as a URI format, but it's approximately file://{path}, plus possibly passing line and col (yes, it really is col, not column) in the OPTIONAL PARAMS part of the OSC 8 hyperlink.

A custom format can be provided for file hyperlinks and the relevant placeholders are path, line, and column. Examples of custom file hyperlink formats:

positron://file{path}:{line}:{column}
vscode://file{path}:{line}:{column}
txmt://open?url=file://{path}&line={line}&column={column}

It's OK if the format includes only path.

User facing environment variables

NO_COLOR

Set to a nonempty value to turn off ANSI colors. See [num_ansi_colors()].

ESS_BACKGROUND_MODE

Set this environment variable to light or dark to indicate dark mode in Emacs. Once https://github.com/emacs-ess/ESS/pull/1178 is merged, ESS will set this automatically.

R_CLI_DYNAMIC

Set to true, TRUE or True to assume a dynamic terminal, that supports \r. Set to anything else to assume a non-dynamic terminal. See [is_dynamic_tty()].

R_CLI_NUM_COLORS

Set to a positive integer to assume a given number of colors. See [num_ansi_colors()].

User facing options

cli.ansi

Set to true, TRUE or True to assume a terminal that supports ANSI control sequences. Set to anything else to assume a non-ANSI terminal. See [is_ansi_tty()].

cli.condition_unicode_bullets

TRUE or FALSE to force turn on or off the Unicode symbols when printing conditions. E.g. in format_error(), format_warning(), format_message() and also in cli_abort(), cli_warn() and cli_inform().

cli.condition_width

Integer scalar (or Inf) to set the console width when cli is formatting errors, warnings or messages in format_error(), format_warning() and format_message(). When formatting conditions this option takes precedence over cli.width.

cli.default_handler

General handler function for all cli conditions. See https://cli.r-lib.org/articles/semantic-cli.html#cli-messages-1

cli.default_num_colors

Default number of ANSI colors. This value is used if the number of colors is not already set by the cli.num_colors option, the R_CLI_NUM_COLORS environment variable, the crayon.enabled and crayon.colors options, the NO_COLOR environment variable, the knitr.in.progress option, a sink() call for the stream.

You can also use this option if color support is detected correctly, but you want to adjust the number of colors. E.g. if crayon.enabled is TRUE, but crayon.colors is not, in Emacs on Windows, * in terminals.

See [num_ansi_colors()]. See also the cli.num_colors option.

cli.dynamic

Set to TRUE to assume a dynamic terminal, that supports \r. Set to anything else to assume a non-dynamic terminal. See [is_dynamic_tty()].

cli.hide_cursor

Whether the cli status bar should try to hide the cursor on terminals. Set the FALSE if the hidden cursor causes issues.

cli.ignore_unknown_rstudio_theme

Set to TRUE to omit a warning for an unknown RStudio theme in code_highlight().

cli.num_colors

Number of ANSI colors. See [num_ansi_colors()]. See also the cli.default_num_colors option.

cli.message_class

Character vector of classes to add to cli's conditions.

cli.progress_bar_style

Progress bar style. See [cli_progress_styles()].

cli.progress_bar_style_ascii

Progress bar style on ASCII consoles. See [cli_progress_styles()].

cli.progress_bar_style_unicode

Progress bar style on Unicode (UTF-8) consoles; See [cli_progress_styles()].

cli.progress_clear

Whether to clear terminated progress bar from the screen on dynamic terminals. See [cli_progress_bar()].

cli.progress_demo_live

Whether cli_progress_demo() should show a live demo, or just record the progress bar frames.

cli.progress_format_download

Default format string for download progress bars.

cli.progress_format_download_nototal

Default format string for download progress bars with unknown totals.

cli.progress_format_iterator

Default format string for iterator progress bars.

cli.progress_format_iterator_nototal

Default format string for iterator progress bars with unknown total number of progress units.

cli.progress_format_tasks

Default format string for tasks progress bars.

cli.progress_format_tasks_nototal

Default format string for tasks progress bars with unknown totals.

cli.progress_handlers

Progress handlers to try. See [cli_progress_builtin_handlers()].

cli.progress_handlers_force

Progress handlers that will always be used, even if another handler was already selected. See [cli_progress_builtin_handlers()].

cli.progress_handlers_only

Progress handlers to force, ignoring handlers set in cli.progress_handlers and cli.progress_handlers_force. See [cli_progress_builtin_handlers()].

cli.progress_say_args

Command line arguments for the say progress handlers. See [cli_progress_builtin_handlers()].

cli.progress_say_command

External command to use in the say progress handler. See [cli_progress_builtin_handlers()].

cli.progress_say_frequency

Minimum delay between say calls in the say progress handler. say ignores very frequent updates, to keep the speech comprehensible. See [cli_progress_builtin_handlers()].

cli.progress_show_after

Delay before showing a progress bar, in seconds. Progress bars that finish before this delay are not shown at all. cli also shows progress bars that have more than 50% to go after half of this delay has passed.

cli.spinner

Default spinner to use, see [get_spinner()].

cli.spinner_ascii

Default spinner to use on ASCII terminals, see [get_spinner()].

cli.spinner_unicode

Default spinner to use on Unicode terminals, see [get_spinner()].

cli.theme

Default cli theme, in addition to the built-in theme. This option in intended for the package developers. See [themes] and [start_app()].

cli.theme_dark

Whether cli should assume a dark theme for the builtin theme. See [builtin_theme()].

cli.unicode

Whether to assume a Unicode terminal. If not set, then it is auto-detected. See [is_utf8_output()].

cli.user_theme

cli user theme. This option is intended for end users. See [themes].

cli.warn_inline_newlines

Whether to emit a warning when cli replaces newline characters with spaces within a {.class } inline style. Defaults to FALSE.

cli.width

Terminal width to assume. If not set, then it is auto-detected. See [console_width()].

rlib_interactive

Whether to assume an interactive R session. If not set, then it is auto-detected.

width

Terminal width. This is used on some platforms, if cli.width is not set.

r-lib/cli documentation built on April 5, 2025, 7:11 p.m.