Helpers for Developing Command Line Interfaces

A suite of tools to build attractive command line interfaces (CLIs), from semantic elements: headers, lists, alerts, paragraphs, etc. Supports theming via a CSS-like language. It also contains a number of lower level CLI elements: rules, boxes, trees, and Unicode symbols with ASCII alternatives. It supports ANSI markup for terminal colors and font styles.

Features

Build a CLI using semantic elements: headings, lists, alerts, paragraphs.
Theming via a CSS-like language.
Terminal colors and font styles.
All cli text can contain interpreted string literals, via the glue package.
Progress bars from R and C code.
Error and warning messages with rich text formatting.
Support for pluralized messages.
ANSI styled string manipulation.

Installation

Install the stable version from CRAN:

install.packages("cli")

Install the development version from GitHub:

pak::pak("r-lib/cli")

Short tour

Some of the more commonly used cli elements, and features.

Short alert messages

One liner messages to inform or warn.

pkgs <- c("foo", "bar", "foobar")
cli_alert_success("Downloaded {length(pkgs)} packages.")

#> ✔ Downloaded 3 packages.

db_url <- "example.com:port"
cli_alert_info("Reopened database {.url {db_url}}.")

#> ℹ Reopened database <example.com:port>.

cli_alert_warning("Cannot reach GitHub, using local database cache.")

#> ! Cannot reach GitHub, using local database cache.

cli_alert_danger("Failed to connect to database.")

#> ✖ Failed to connect to database.

cli_alert("A generic alert")

#> → A generic alert

Headings

Three levels of headings.

cli_h1("Heading 1")

#>
#> ── Heading 1 ───────────────────────────────────────────────────────────────────

cli_h2("Heading 2")

#>
#> ── Heading 2 ──
#>

cli_h3("Heading 3")

#> ── Heading 3

Lists

Ordered, unordered and description lists, that can be nested.

fun <- function() {
  cli_ol()
  cli_li("Item 1")
  ulid <- cli_ul()
  cli_li("Subitem 1")
  cli_li("Subitem 2")
  cli_end(ulid)
  cli_li("Item 2")
  cli_end()
}
fun()

#> 1. Item 1
#>   • Subitem 1
#>   • Subitem 2
#> 2. Item 2

Themes

Theming via a CSS-like language.

fun <- function() {
  cli_div(theme = list(span.emph = list(color = "orange")))
  cli_text("This is very {.emph important}")
  cli_end()
  cli_text("Back to the {.emph previous theme}")
}
fun()

#> This is very important
#> Back to the previous theme

Command substitution

Automatic command substitution via the glue package.

size <- 123143123
dt <- 1.3454
cli_alert_info(c(
  "Downloaded {prettyunits::pretty_bytes(size)} in ",
  "{prettyunits::pretty_sec(dt)}"))

#> ℹ Downloaded 123.14 MB in 1.3s

Pluralization

Pluralization support.

nfiles <- 3
ndirs <- 1
cli_alert_info("Found {nfiles} file{?s} and {ndirs} director{?y/ies}.")

#> ℹ Found 3 files and 1 directory.

Progress bars

clean <- function() {
  cli_progress_bar("Cleaning data", total = 100)
  for (i in 1:100) {
    Sys.sleep(5/100)
    cli_progress_update()
  }
}
clean()

Documentation

See at https://cli.r-lib.org/ and also in the installed package: help(package = "cli").

Code of Conduct

Please note that the cli project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.

cli