brew/docs/Cask-Cookbook.md

Cask Cookbook

Each cask is a Ruby block, beginning with a special header line. The cask definition itself is always enclosed in a do … end block. Example:

cask "alfred" do
  version "2.7.1_387"
  sha256 "a3738d0513d736918a6d71535ef3d85dd184af267c05698e49ac4c6b48f38e17"

  url "https://cachefly.alfredapp.com/Alfred_#{version}.zip"
  name "Alfred"
  desc "Application launcher and productivity software"
  homepage "https://www.alfredapp.com/"

  app "Alfred 2.app"
  app "Alfred 2.app/Contents/Preferences/Alfred Preferences.app"
end

• Table of Contents {:toc}

The Cask Language Is Declarative

Each cask contains a series of stanzas (or “fields”) which declare how the software is to be obtained and installed. In a declarative language, the author does not need to worry about order. As long as all the needed fields are present, Homebrew Cask will figure out what needs to be done at install time.

To make maintenance easier, the most-frequently-updated stanzas are usually placed at the top. But that’s a convention, not a rule.

Exception: do blocks such as postflight may enclose a block of pure Ruby code. Lines within that block follow a procedural (order-dependent) paradigm.

Conditional Statements

Efficiency

Conditional statements are permitted, but only if they are very efficient. Tests on the following values are known to be acceptable:

value	examples
MacOS.version	bbedit.rb, powerphotos.rb, choosy.rb

Version Comparisons

Tests against MacOS.version may use either one of these symbolic names or version strings with numeric comparison operators:

if MacOS.version <= :mojave        # symbolic name

if MacOS.version <= "10.14"        # version string for major release

Note that in the official Homebrew Cask taps only the symbolic names are allowed. The numeric comparison may only be used for third-party taps.

Always Fall Through to the Newest Case

Conditionals should be constructed so that the default is the newest OS version. When using an if statement, test for older versions, and then let the else statement hold the latest and greatest. This makes it more likely that the cask will work without alteration when a new OS version is released. Example (from calibre.rb):

if MacOS.version <= :high_sierra
  # ...
elsif MacOS.version <= :mojave
  # ...
else
  # ...
end

Switch Between Languages or Regions

If a cask is available in multiple languages, you can use the language stanza to switch between languages or regions based on the system locale.

Arbitrary Ruby Methods

In the exceptional case that the cask DSL is insufficient, it is possible to define arbitrary Ruby variables and methods inside the cask by creating a Utils namespace. Example:

cask "myapp" do
  module Utils
    def self.arbitrary_method
      ...
    end
  end

  name "MyApp"
  version "1.0"
  sha256 "a32565cdb1673f4071593d4cc9e1c26bc884218b62fef8abc450daa47ba8fa92"

  url "https://#{Utils.arbitrary_method}"
  homepage "https://www.example.com/"
  ...
end

This should be used sparingly: any method which is needed by two or more casks should instead be rolled into Homebrew/brew. Care must also be taken that such methods be very efficient.

Variables and methods should not be defined outside the Utils namespace, as they may collide with Homebrew Cask internals.

Header Line Details

The first non-comment line in a cask follows the form:

cask "<cask-token>" do

<cask-token> should match the cask filename, without the .rb extension, enclosed in double quotes.

There are currently some arbitrary limitations on cask tokens which are in the process of being removed. GitHub Actions will catch any errors during the transition.

Stanza order

Having a common order for stanzas makes casks easier to update and parse. Below is the complete stanza sequence (no cask will have all stanzas). The empty lines shown here are also important, as they help to visually delimit information.

version
sha256

language

url
name
desc
homepage

livecheck

auto_updates
conflicts_with
depends_on
container

suite
app
pkg
installer
binary
manpage
colorpicker
dictionary
font
input_method
internet_plugin
keyboard_layout
prefpane
qlplugin
mdimporter
screen_saver
service
audio_unit_plugin
vst_plugin
vst3_plugin
artifact, target: # target: shown here as is required with `artifact`
stage_only

preflight

postflight

uninstall_preflight

uninstall_postflight

uninstall

zap

caveats

Note that every stanza that has additional parameters (:symbols after a ,) shall have them on separate lines, one per line, in alphabetical order. An exception is target: which typically consists of short lines.

Stanzas

Required Stanzas

Each of the following stanzas is required for every cask.

name	multiple occurrences allowed?	value
version	no	Application version.
sha256	no	SHA-256 checksum of the file downloaded from url, calculated by the command shasum -a 256 <file>. Can be suppressed by using the special value :no_check.
url	no	URL to the .dmg/.zip/.tgz/.tbz2 file that contains the application. A comment should be added if the domains in the url and homepage stanzas differ. Block syntax should be used for URLs that change on every visit.
name	yes	String providing the full and proper name defined by the vendor.
desc	no	One-line description of the cask. Shown when running brew info.
homepage	no	Application homepage; used for the brew home command.

At Least One Artifact Stanza Is Also Required

Each cask must declare one or more artifacts (i.e. something to install).

name	multiple occurrences allowed?	value
app	yes	Relative path to an .app that should be moved into the /Applications folder on installation.
suite	yes	Relative path to a containing directory that should be moved into the /Applications folder on installation.
pkg	yes	Relative path to a .pkg file containing the distribution.
installer	yes	Describes an executable which must be run to complete the installation.
binary	yes	Relative path to a Binary that should be linked into the $(brew --prefix)/bin folder on installation.
manpage	yes	Relative path to a Man Page that should be linked into the respective man page folder on installation, e.g. /usr/local/share/man/man3 for my_app.3.
colorpicker	yes	Relative path to a ColorPicker plugin that should be moved into the ~/Library/ColorPickers folder on installation.
dictionary	yes	Relative path to a Dictionary that should be moved into the ~/Library/Dictionaries folder on installation.
font	yes	Relative path to a Font that should be moved into the ~/Library/Fonts folder on installation.
input_method	yes	Relative path to an Input Method that should be moved into the ~/Library/Input Methods folder on installation.
internet_plugin	yes	Relative path to an Internet Plugin that should be moved into the ~/Library/Internet Plug-Ins folder on installation.
keyboard_layout	yes	Relative path to a Keyboard Layout that should be moved into the /Library/Keyboard Layouts folder on installation.
prefpane	yes	Relative path to a Preference Pane that should be moved into the ~/Library/PreferencePanes folder on installation.
qlplugin	yes	Relative path to a QuickLook Plugin that should be moved into the ~/Library/QuickLook folder on installation.
mdimporter	yes	Relative path to a Spotlight Metadata Importer that should be moved into the ~/Library/Spotlight folder on installation.
screen_saver	yes	Relative path to a Screen Saver that should be moved into the ~/Library/Screen Savers folder on installation.
service	yes	Relative path to a Service that should be moved into the ~/Library/Services folder on installation.
audio_unit_plugin	yes	Relative path to an Audio Unit Plugin that should be moved into the ~/Library/Audio/Components folder on installation.
vst_plugin	yes	Relative path to a VST Plugin that should be moved into the ~/Library/Audio/VST folder on installation.
vst3_plugin	yes	Relative path to a VST3 Plugin that should be moved into the ~/Library/Audio/VST3 folder on installation.
artifact	yes	Relative path to an arbitrary path that should be moved on installation. Must provide an absolute path as a target. (Example: free-gpgmail.rb) This is only for unusual cases; the app stanza is strongly preferred when moving .app bundles.
stage_only	no	true. Asserts that the cask contains no activatable artifacts.

Optional Stanzas

name	multiple occurrences allowed?	value
uninstall	yes	Procedures to uninstall a cask. Optional unless the pkg stanza is used.
zap	yes	Additional procedures for a more complete uninstall, including user files and shared resources.
depends_on	yes	List of dependencies and requirements for this cask.
conflicts_with	yes	List of conflicts with this cask (not yet functional).
caveats	yes	String or Ruby block providing the user with cask-specific information at install time.
livecheck	no	Ruby block describing how to find updates for this cask. Supersedes appcast.
preflight	yes	Ruby block containing preflight install operations (needed only in very rare cases).
postflight	yes	Ruby block containing postflight install operations.
uninstall_preflight	yes	Ruby block containing preflight uninstall operations (needed only in very rare cases).
uninstall_postflight	yes	Ruby block containing postflight uninstall operations.
language	required	Ruby block, called with language code parameters, containing other stanzas and/or a return value.
container nested:	no	Relative path to an inner container that must be extracted before moving on with the installation. This allows for support of .dmg inside .tar, .zip inside .dmg, etc.
container type:	no	Symbol to override container-type autodetect. May be one of: :air, :bz2, :cab, :dmg, :generic_unar, :gzip, :otf, :pkg, :rar, :seven_zip, :sit, :tar, :ttf, :xar, :zip, :naked. (Example: parse.rb)
auto_updates	no	true. Asserts that the cask artifacts auto-update. Use if Check for Updates… or similar is present in an app menu, but not if it only opens a webpage and does not do the download and installation for you.

Stanza descriptions

Stanza: app

In the simple case of a string argument to app, the source file is moved to the target /Applications directory. For example:

app "Alfred 2.app"

by default moves the source to:

/Applications/Alfred 2.app

Renaming the Target

You can rename the target which appears in your /Applications directory by adding a target: key to app. Example (from scala-ide.rb):

app "eclipse.app", target: "Scala IDE.app"

target May Contain an Absolute Path

If target: has a leading slash, it is interpreted as an absolute path. The containing directory for the absolute path will be created if it does not already exist. Example (from sapmachine-jdk.rb):

artifact "sapmachine-jdk-#{version}.jdk", target: "/Library/Java/JavaVirtualMachines/sapmachine-jdk-#{version}.jdk"

target Works on Most Artifact Types

The target: key works similarly for most cask artifacts, such as app, binary, colorpicker, dictionary, font, input_method, internet_plugin, keyboard_layout, prefpane, qlplugin, mdimporter, screen_saver, service, suite, audio_unit_plugin, vst_plugin, vst3_plugin, and artifact.

target Should Only Be Used in Select Cases

Don’t use target: for aesthetic reasons, like removing version numbers (app "Slack #{version}.app", target: "Slack.app"). Use it when it makes sense functionally and document your reason clearly in the cask, using one of the templates: for clarity; for consistency; to prevent conflicts; due to developer suggestion.

Stanza: binary

In the simple case of a string argument to binary, the source file is linked into the $(brew --prefix)/bin directory on installation. For example (from operadriver.rb):

binary "operadriver_mac64/operadriver"

creates a symlink to:

$(brew --prefix)/bin/operadriver

from a source file such as:

$(brew --caskroom)/operadriver/106.0.5249.119/operadriver_mac64/operadriver

A binary (or multiple) can also be contained in an application bundle:

app "Atom.app"
binary "#{appdir}/Atom.app/Contents/Resources/app/apm/bin/apm"

You can rename the target which appears in your binaries directory by adding a target: key to binary:

binary "#{appdir}/Atom.app/Contents/Resources/app/atom.sh", target: "atom"

Behaviour and usage of target: is the same as with app. However, for binary the select cases don’t apply as rigidly. It’s fine to take extra liberties with target: to be consistent with other command-line tools, like changing case, removing an extension, or cleaning up the name.

Stanza: caveats

Sometimes there are particularities with the installation of a piece of software that cannot or should not be handled programmatically by Homebrew Cask. In those instances, caveats is the way to inform the user. Information in caveats is displayed when a cask is invoked with either install or info.

To avoid flooding users with too many messages (thus desensitising them to the important ones), caveats should be used sparingly and exclusively for installation-related matters. If you’re not sure a caveat you find pertinent is installation-related or not, ask a maintainer. As a general rule, if your case isn’t already covered in our comprehensive caveats Mini-DSL, it’s unlikely to be accepted.

caveats as a String

When caveats is a string, it is evaluated at compile time. The following methods are available for interpolation if caveats is placed in its customary position at the end of the cask:

method	description
token	the cask token
version	the cask version
homepage	the cask homepage
caskroom_path	the containing directory for this cask: $(brew --caskroom)/<token> (only available with block form)
staged_path	the staged location for this cask, including version number: $(brew --caskroom)/<token>/<version> (only available with block form)

Example:

caveats "Using #{token} may be hazardous to your health."

caveats as a Block

When caveats is a Ruby block, evaluation is deferred until install time. Within a block you may refer to the @cask instance variable, and invoke any method available on @cask.

caveats Mini-DSL

There is a mini-DSL available within caveats blocks.

The following methods may be called to generate standard warning messages:

method	description
path_environment_variable "path"	Users should make sure path is in their PATH environment variable.
zsh_path_helper "path"	zsh users must take additional steps to make sure path is in their PATH environment variable.
depends_on_java "version"	Users should make sure they have the specified version of Java installed. version can be exact (e.g. 6), a minimum (e.g. 7+), or omitted (when any version works).
requires_rosetta	The cask requires Rosetta 2 for it to run on Apple Silicon.
logout	Users should log out and log back in to complete installation.
reboot	Users should reboot to complete installation.
files_in_usr_local	The cask installs files to /usr/local, which may confuse Homebrew.
discontinued	All software development has been officially discontinued upstream.
kext	Users may need to enable their kexts in System Settings → Privacy & Security (or System Preferences → Security & Privacy → General in earlier macOS versions).
unsigned_accessibility	Users will need to re-enable the app on each update in System Settings → Privacy & Security (or System Preferences → Security & Privacy → Privacy in earlier macOS versions) as it is unsigned.
license "web_page"	Users may find the software's usage license at web_page.
free_license "web_page"	Users may obtain an official license to use the software at web_page.

Example:

caveats do
  path_environment_variable "/usr/texbin"
end

Stanza: conflicts_with

conflicts_with is used to declare conflicts that keep a cask from installing or working correctly.

conflicts_with cask

The value should be another cask token.

Example: Wireshark, which conflicts with wireshark-chmodbpf.

conflicts_with cask: "wireshark-chmodbpf"

conflicts_with formula

Note: conflicts_with formula: is a stub and is not yet functional.

The value should be another formula name.

Example: MacVim, which conflicts with the macvim formula.

conflicts_with formula: "macvim"

Stanza: depends_on

depends_on is used to declare dependencies and requirements for a cask. depends_on is not consulted until install is attempted.

depends_on cask

The value should be another cask token, needed by the current cask.

Example: NTFSTool, which depends on macFUSE.

depends_on cask: "macfuse"

depends_on formula

The value should name a Homebrew formula needed by the cask.

Example: some distributions are contained in archive formats such as 7z which are not supported by stock Apple tools. For these cases, a more capable archive reader may be pulled in at install time by declaring a dependency on the unar formula:

depends_on formula: "unar"

depends_on macos

Requiring an Exact macOS Release

The value for depends_on macos: may be a symbol or an array of symbols, listing the exact compatible macOS releases.

The available values for macOS releases are:

symbol	corresponding release
:el_capitan	10.11
:sierra	10.12
:high_sierra	10.13
:mojave	10.14
:catalina	10.15
:big_sur	11
:monterey	12
:ventura	13

Only major releases are covered (version numbers containing a single dot). The symbol form is used for readability. The following are all valid ways to enumerate the exact macOS release requirements for a cask:

depends_on macos: :big_sur
depends_on macos: [
  :catalina,
  :big_sur,
]

Setting a Minimum macOS Release

depends_on macos: can also accept a string starting with a comparison operator such as >=, followed by an macOS release in the form above. The following is a valid expression meaning “at least macOS Big Sur (11.0)”:

depends_on macos: ">= :big_sur"

A comparison expression cannot be combined with any other form of depends_on macos:.

depends_on arch

The value for depends_on arch: may be a symbol or an array of symbols, listing the hardware compatibility requirements for a cask. The requirement is satisfied at install time if any one of multiple arch: values matches the user’s hardware.

The available symbols for hardware are:

symbol	meaning
:x86_64	64-bit Intel
:intel	64-bit Intel
:arm64	Apple Silicon

The following are all valid expressions:

depends_on arch: :intel
depends_on arch: :x86_64            # same meaning as above
depends_on arch: [:x86_64]          # same meaning as above
depends_on arch: :arm64

depends_on Parameters

key	description
formula:	Homebrew formula
cask:	cask token
macos:	symbol, string, array, or comparison expression defining macOS release requirements
arch:	symbol or array defining hardware requirements
java:	stub - not yet functional

Stanza: desc

desc accepts a single-line UTF-8 string containing a short description of the software. It’s used to help with searchability and disambiguation, thus it must concisely describe what the software does (or what you can accomplish with it).

desc is not for app slogans! Vendors’ descriptions tend to be filled with generic adjectives such as “modern” and “lightweight”. Those are meaningless marketing fluff (do you ever see apps proudly describing themselves as outdated and bulky?) which must the deleted. It’s fine to use the information on the software’s website as a starting point, but it will require editing in almost all cases.

Dos and Don'ts

• Do start with an uppercase letter.

  - desc "sound and music editor"
  + desc "Sound and music editor"
  

• Do be brief, i.e. use less than 80 characters.

  - desc "Sound and music editor which comes with effects, instruments, sounds and all kinds of creative features"
  + desc "Sound and music editor"
  

• Do describe what the software does or is.

  - desc "Development of musical ideas made easy"
  + desc "Sound and music editor"
  

• Do not include the platform. Casks only work on macOS, so this is redundant information.

  - desc "Sound and music editor for macOS"
  + desc "Sound and music editor"
  

• Do not include the cask’s name.

  - desc "Ableton Live is a sound and music editor"
  + desc "Sound and music editor"
  

• Do not include the vendor. This should be added to the cask’s name instead.

  - desc "Sound and music editor made by Ableton"
  + desc "Sound and music editor"
  

• Do not add user pronouns.

  - desc "Edit your music files"
  + desc "Sound and music editor"
  

• Do not use empty marketing jargon.

  - desc "Beautiful and powerful modern sound and music editor"
  + desc "Sound and music editor"
  

Stanza: *flight

The stanzas preflight, postflight, uninstall_preflight, and uninstall_postflight define operations to be run before or after installation or uninstallation.

Evaluation of Blocks is Always Deferred

The Ruby blocks defined by these stanzas are not evaluated until install time or uninstall time. Within a block you may refer to the @cask instance variable, and invoke any method available on @cask.

*flight Mini-DSL

There is a mini-DSL available within these blocks.

The following methods may be called to perform standard tasks:

method	availability	description
set_ownership(paths)	preflight, postflight, uninstall_preflight	Set user and group ownership of paths. (Example: docker-toolbox.rb)
set_permissions(paths, permissions_str)	preflight, postflight, uninstall_preflight	Set permissions in paths to permissions_str. (Example: ngrok.rb)

set_ownership(paths) defaults user ownership to the current user and group ownership to staff. These can be changed by passing in extra options: set_ownership(paths, user: "user", group: "group"). (Example: wsjtx.rb)

Stanza: installer

This stanza must always be accompanied by uninstall.

The installer stanza takes a series of key-value pairs, the first key of which must be manual: or script:.

installer manual

installer manual: takes a single string value, describing a GUI installer which must be run by the user at a later time. The path may be absolute, or relative to the cask. Example (from nutstore.rb):

installer manual: "Nutstore Installer.app"

installer script

installer script: introduces a series of key-value pairs describing a command which will automate completion of the install. It should never be used for interactive installations. The form is similar to uninstall script::

key	value
executable:	path to an install script to be run
args:	array of arguments to the install script
input:	array of lines of input to be sent to stdin of the script
must_succeed:	set to false if the script is allowed to fail
sudo:	set to true if the script needs sudo

The path may be absolute, or relative to the cask. Example (from miniforge.rb):

installer script: {
  executable: "Miniforge3-#{version}-MacOSX-x86_64.sh",
  args:       ["-b", "-p", "#{caskroom_path}/base"],
}

If the installer script: does not require any of the key-values it can point directly to the path of the install script:

installer script: "#{staged_path}/install.sh"

Stanza: language

The language stanza can match ISO 639-1 language codes, script codes (ISO 15924) and regional identifiers (ISO 3166-1 Alpha 2), or a combination thereof.

US English should always be used as the default language:

language "zh", "CN" do
  "zh_CN"
end

language "de" do
  "de_DE"
end

language "en-GB" do
  "en_GB"
end

language "en", default: true do
  "en_US"
end

Note that the following are not the same:

language "en", "GB" do
  # matches all locales containing "en" or "GB"
end

language "en-GB" do
  # matches only locales containing "en" and "GB"
end

The return value of the matching language block can be accessed by simply calling language.

homepage "https://example.org/#{language}"

Examples: firefox.rb, battle-net.rb

Installation

To install a cask in a specific language, you can pass the --language= option to brew install:

brew install firefox --language=it

Stanza: livecheck

The livecheck stanza is used to automatically fetch the latest version of a cask from changelogs, release notes, appcasts, etc. Since the main homebrew/cask repository only accepts submissions for stable versions of software (and documented exceptions), this allows for verifying that the submitted version is the latest, and alerting when a newer version is available using brew livecheck.

Every livecheck block must contain a url, which can be either a string or a symbol pointing to other URLs in the cask (:url or :homepage).

Additionally, a livecheck should specify which strategy should be used to extract the version:

strategy	description
:header_match	extract version from HTTP headers (e.g. Location or Content-Disposition)
:page_match	extract version from page contents
:sparkle	extract version from Sparkle appcast contents
:extract_plist	extract version from a .plist in the downloaded artifact

Here is a basic example, extracting a simple version from a page:

livecheck do
  url "https://example.org/my-app/download"
  strategy :page_match
  regex(%r{href=.*?/MyApp-(\d+(?:\.\d+)*)\.zip}i)
end

If the download URL is present on the homepage, we can use a symbol instead of a string:

livecheck do
  url :homepage
  strategy :page_match
  regex(%r{href=.*?/MyApp-(\d+(?:\.\d+)*)\.zip}i)
end

The :header_match strategy will try to parse a version from the filename (in the Content-Disposition header) and the final URL (in the Location header). If that doesn't work, a regex can be specified, e.g.:

strategy :header_match
regex(/MyApp-(\d+(?:\.\d+)*)\.zip/i)

If the version depends on multiple header fields, a block can be specified, e.g.:

strategy :header_match do |headers|
  v = headers["content-disposition"][/MyApp-(\d+(?:\.\d+)*)\.zip/i, 1]
  id = headers["location"][%r{/(\d+)/download$}i, 1]
  next if v.blank? || id.blank?

  "#{v},#{id}"
end

Similarly, the :page_match strategy can also be used for more complex versions by specifying a block:

strategy :page_match do |page|
  match = page.match(%r{href=.*?/(\d+)/MyApp-(\d+(?:\.\d+)*)\.zip}i)
  next if match.blank?

  "#{match[2]},#{match[1]}"
end

The :sparkle strategy takes a URL for an XML feed providing release information to an app that self-updates using the Sparkle framework. This URL can be found within the app bundle as the SUFeedURL property in Contents/Info.plist or by using the find-appcast script. Run it with:

"$(brew --repository homebrew/cask)/developer/bin/find-appcast" '/path/to/application.app'

Both the sparkle:version and sparkle:shortVersionString attributes are checked by default; if only one is needed, specify &:version or &:short_version:

url "https://manytricks.com/butler/appcast/"
strategy :sparkle, &:short_version

If no means are available online for checking which version is current, as a last resort the :extract_plist strategy will have brew livecheck download the artifact and retrieve its version string from Contents/Info.plist.

Stanza: name

name accepts a UTF-8 string defining the name of the software, including capitalization and punctuation. It is used to help with searchability and disambiguation.

Unlike the token, which is simplified and reduced to a limited set of characters, the name stanza can include the proper capitalization, spacing and punctuation to match the official name of the software. For disambiguation purposes, it is recommended to spell out the name of the application, including the vendor name if necessary. A good example is the pycharm-ce cask, whose name is spelled out as Jetbrains PyCharm Community Edition, even though it is likely never referenced as such anywhere.

Additional details about the software can be provided in the desc stanza.

The name stanza can be repeated multiple times if there are useful alternative names. The first instance should use the Latin alphabet. For example, see the cave-story cask, whose original name does not use the Latin alphabet.

Stanza: pkg

This stanza must always be accompanied by uninstall.

The first argument to the pkg stanza should be a relative path to the .pkg file to be installed. Example:

pkg "Unity.pkg"

Subsequent arguments to pkg are key/value pairs which modify the install process. Currently supported keys are allow_untrusted: and choices:.

pkg allow_untrusted

pkg allow_untrusted: true can be used to install a .pkg containing an untrusted certificate by passing -allowUntrusted to /usr/sbin/installer.

This option is not permitted in official Homebrew Cask taps; it is only provided for use in third-party taps or local casks.

Example (from alinof-timer.rb):

pkg "AlinofTimer.pkg", allow_untrusted: true

pkg choices

pkg choices: can be used to override a .pkg’s default install options via -applyChoiceChangesXML. It uses a deserialized version of the choiceChanges property list (refer to the CHOICE CHANGES FILE section of the installer manual page by running man -P 'less --pattern "^CHOICE CHANGES FILE"' installer).

Running this macOS installer command:

installer -showChoicesXML -pkg '/path/to/my.pkg'

will output XML that you can use to extract the choices: values, as well as their equivalents to the GUI options.

See this pull request for wireshark-chmodbpf and this one for wine-staging for some examples of the procedure.

Example (from lando.rb):

pkg "LandoInstaller.pkg",
    choices: [
      {
        "choiceIdentifier" => "choiceDocker",
        "choiceAttribute"  => "selected",
        "attributeSetting" => 0,
      },
      {
        "choiceIdentifier" => "choiceLando",
        "choiceAttribute"  => "selected",
        "attributeSetting" => 1,
      },
    ]

Example (from microsoft-office.rb):

pkg "Microsoft_Office_#{version}_Installer.pkg",
    choices: [
      {
        "choiceIdentifier" => "com.microsoft.autoupdate", # Office16_all_autoupdate.pkg
        "choiceAttribute"  => "selected",
        "attributeSetting" => 0,
      },
    ]

Stanza: sha256

Calculating the SHA-256

The sha256 value is usually calculated by the shasum command:

shasum --algorithm 256 <file>

Special Value :no_check

The special value sha256 :no_check is used to turn off SHA checking whenever checksumming is impractical due to the upstream configuration.

version :latest requires sha256 :no_check, and this pairing is common. However, sha256 :no_check does not require version :latest.

We use a checksum whenever possible.

Stanza: suite

Some distributions provide a suite of multiple applications, or an application with required data, to be installed together in a subdirectory of /Applications.

For these casks, use the suite stanza to define the directory containing the application suite. Example (from sketchup.rb):

suite "SketchUp #{version.csv.first}"

The value of suite is never an .app bundle, but a plain directory.

Stanza: uninstall

If you cannot design a working uninstall stanza, please submit your cask anyway. The maintainers can help you write an uninstall stanza, just ask!

uninstall pkgutil: Is The Easiest and Most Useful

The easiest and most useful uninstall directive is pkgutil:. It should cover most use cases.

uninstall Is Required for Casks That Install using pkg or installer manual:

For most casks, uninstall actions are determined automatically, and an explicit uninstall stanza is not needed. However, a cask which uses the pkg or installer manual: stanzas will not know how to uninstall correctly unless an uninstall stanza is given.

So, while the cask DSL does not enforce the requirement, it is much better for users if every pkg and installer manual: has a corresponding uninstall.

The uninstall stanza is available for non-pkg casks, and is useful for a few corner cases. However, the documentation below concerns the typical case of using uninstall to define procedures for a pkg.

There Are Multiple Uninstall Techniques

Since pkg installers can do arbitrary things, different techniques are needed to uninstall in each case. You may need to specify one, or several, of the following key/value pairs as arguments to uninstall.

Summary of Keys

• early_script: (string or hash) - like script:, but runs early (for special cases, best avoided)
• launchctl: (string or array) - IDs of launchd jobs to remove
• quit: (string or array) - bundle IDs of running applications to quit
• signal: (array of arrays) - signal numbers and bundle IDs of running applications to send a Unix signal to (for when quit: does not work)
• login_item: (string or array) - names of login items to remove
• kext: (string or array) - bundle IDs of kexts to unload from the system
• script: (string or hash) - relative path to an uninstall script to be run via sudo; use hash if args are needed
  • executable: - relative path to an uninstall script to be run via sudo (required for hash form)
  • args: - array of arguments to the uninstall script
  • input: - array of lines of input to be sent to stdin of the script
  • must_succeed: - set to false if the script is allowed to fail
  • sudo: - set to true if the script needs sudo
• pkgutil: (string, regexp or array of strings and regexps) - strings or regexps matching bundle IDs of packages to uninstall using pkgutil
• delete: (string or array) - double-quoted, absolute paths of files or directory trees to remove. Should only be used as a last resort; pkgutil: is strongly preferred.
• rmdir: (string or array) - double-quoted, absolute paths of directories to remove if empty. Works recursively.
• trash: (string or array) - double-quoted, absolute paths of files or directory trees to move to Trash

Each uninstall technique is applied according to the order above. The order in which uninstall keys appear in the cask file is ignored.

For assistance filling in the right values for uninstall keys, there are several helper scripts found under developer/bin in the Homebrew Cask repository. Each of these scripts responds to the -help option with additional documentation.

Working out an uninstall stanza is easiest when done on a system where the package is currently installed and operational. To operate on an uninstalled .pkg file, see Working With a .pkg File Manually, below.

uninstall pkgutil

This is the most useful uninstall key. pkgutil: is often sufficient to completely uninstall a pkg, and is strongly preferred over delete:.

IDs for the most recently installed packages can be listed using list_recent_pkg_ids:

"$(brew --repository homebrew/cask)/developer/bin/list_recent_pkg_ids"

pkgutil: also accepts a regular expression match against multiple package IDs. The regular expressions are somewhat nonstandard. To test a pkgutil: regular expression against currently installed packages, use list_pkg_ids_by_regexp:

"$(brew --repository homebrew/cask)/developer/bin/list_pkg_ids_by_regexp" <regular-expression>

List Files Associated With a Package ID

Once you know the ID for an installed package (see above), you can list all files on your system associated with that package ID using the macOS pkgutil command:

pkgutil --files <package.id.goes.here>

Listing the associated files can help you assess whether the package included any launchd jobs or kernel extensions (kexts).

uninstall launchctl

IDs for currently loaded launchd jobs can be listed using list_loaded_launchjob_ids:

"$(brew --repository homebrew/cask)/developer/bin/list_loaded_launchjob_ids"

IDs for all installed launchd jobs can be listed using list_installed_launchjob_ids:

"$(brew --repository homebrew/cask)/developer/bin/list_installed_launchjob_ids"

uninstall quit

Bundle IDs for currently running applications can be listed using list_running_app_ids:

"$(brew --repository homebrew/cask)/developer/bin/list_running_app_ids"

Bundle IDs inside an application bundle on disk can be listed using list_ids_in_app:

"$(brew --repository homebrew/cask)/developer/bin/list_ids_in_app" '/path/to/application.app'

uninstall signal

signal: should only be needed in the rare case that a process does not respond to quit:.

Bundle IDs for signal: targets may be obtained in the same way as for quit:. The value for signal: is an array-of-arrays, with each cell containing two elements: the desired Unix signal followed by the corresponding bundle ID.

The Unix signal may be given in numeric or string form (see the kill(1) man page for more details).

The elements of the signal: array are applied in order, only if there is an existing process associated the bundle ID, and stopping when that process terminates. A bundle ID may be repeated to send more than one signal to the same process.

It is better to use the least-severe signals that are sufficient to stop a process. The KILL signal in particular can have unwanted side effects.

An example, with commonly used signals in ascending order of severity:

uninstall signal: [
            ["TERM", "fr.madrau.switchresx.daemon"],
            ["QUIT", "fr.madrau.switchresx.daemon"],
            ["INT",  "fr.madrau.switchresx.daemon"],
            ["HUP",  "fr.madrau.switchresx.daemon"],
            ["KILL", "fr.madrau.switchresx.daemon"],
          ]

Note that when multiple running processes match the given bundle ID, all matching processes will be signaled.

Unlike quit: directives, Unix signals originate from the current user, not from the superuser. This is construed as a safety feature, since the superuser is capable of bringing down the system via signals. However, this inconsistency may also be considered a bug, and should be addressed in some fashion in a future version.

uninstall login_item

Login items associated with an application bundle on disk can be listed using list_login_items_for_app:

"$(brew --repository homebrew/cask)/developer/bin/list_login_items_for_app" '/path/to/application.app'

Note that you will likely need to have opened the app at least once for any login items to be present.

uninstall kext

IDs for currently loaded kernel extensions can be listed using list_loaded_kext_ids:

"$(brew --repository homebrew/cask)/developer/bin/list_loaded_kext_ids"

IDs inside a kext bundle on disk can be listed using list_id_in_kext:

"$(brew --repository homebrew/cask)/developer/bin/list_id_in_kext" '/path/to/name.kext'

uninstall script

uninstall script: introduces a series of key-value pairs describing a command which will automate completion of the uninstall. Example (from virtualbox.rb):

uninstall script:  {
            executable: "VirtualBox_Uninstall.tool",
            args:       ["--unattended"],
            sudo:       true,
          },
          pkgutil: "org.virtualbox.pkg.*",
          delete:  "/usr/local/bin/vboximg-mount"

It is important to note that, although script: in the above example does attempt to completely uninstall the pkg, it should not be used in place of pkgutil:, but as a complement when possible.

uninstall delete

delete: should only be used as a last resort, if other uninstall methods are insufficient.

Arguments to uninstall delete: should use the following basic rules:

• Basic tilde expansion is performed on paths, i.e. leading ~ is expanded to the home directory.
• Paths must be absolute.
• Glob expansion is performed using the standard set of characters.

To remove user-specific files, use the zap stanza.

uninstall trash

trash: arguments follow the same rules listed above for delete:.

Working With a .pkg File Manually

Advanced users may wish to work with a .pkg file manually, without having the package installed.

A list of files which may be installed from a .pkg can be extracted using list_payload_in_pkg:

"$(brew --repository homebrew/cask)/developer/bin/list_payload_in_pkg" '/path/to/my.pkg'

Candidate application names helpful for determining the name of a cask may be extracted from a .pkg file using list_apps_in_pkg:

"$(brew --repository homebrew/cask)/developer/bin/list_apps_in_pkg" '/path/to/my.pkg'

Candidate package IDs which may be useful in a pkgutil: key may be extracted from a .pkg file using list_ids_in_pkg:

"$(brew --repository homebrew/cask)/developer/bin/list_ids_in_pkg" '/path/to/my.pkg'

A fully manual method for finding bundle IDs in a package file follows:

1. Unpack /path/to/my.pkg (replace with your package name) with pkgutil --expand /path/to/my.pkg /tmp/expanded.unpkg.
2. The unpacked package is a folder. Bundle IDs are contained within files named PackageInfo. These files can be found with the command find /tmp/expanded.unpkg -name PackageInfo.
3. PackageInfo files are XML files, and bundle IDs are found within the identifier attributes of <pkg-info> tags that look like <pkg-info ... identifier="com.oracle.jdk7u51" ... >, where extraneous attributes have been snipped out and replaced with ellipses.
4. Kexts inside packages are also described in PackageInfo files. If any kernel extensions are present, the command find /tmp/expanded.unpkg -name PackageInfo -print0 | xargs -0 grep -i kext should return a <bundle id> tag with a path attribute that contains a .kext extension, for example <bundle id="com.wavtap.driver.WavTap" ... path="./WavTap.kext" ... />.
5. Once bundle IDs have been identified, the unpacked package directory can be deleted.

Stanza: url

HTTPS URLs are Preferred

If available, an HTTPS URL is preferred. A plain HTTP URL should only be used in the absence of a secure alternative.

Additional url Parameters

When a plain URL string is insufficient to fetch a file, additional information may be provided to the curl-based downloader, in the form of key/value pairs appended to url:

key	value
verified:	string repeating the beginning of url, for verification purposes
using:	the symbol :post is the only legal value
cookies:	hash of cookies to be set in the download request
referer:	string holding the URL to set as referer in the download request
header:	string or array of strings holding the header(s) to set for the download request
user_agent:	string holding the user agent to set for the download request. Can also be set to the symbol :fake, which will use a generic browser-like user agent string. We prefer :fake when the server does not require a specific user agent.
data:	hash of parameters to be set in the POST request

Example of using cookies:: oracle-jdk-javadoc.rb

Example of using referer:: firealpaca.rb

Example of using header:: issue-325182724 issue-15590

When URL and Homepage Domains Differ, Add verified:

When the domains of url and homepage differ, the discrepancy should be documented with the verified: parameter, repeating the smallest possible portion of the URL that uniquely identifies the app or vendor, excluding the protocol. (Example: shotcut.rb)

This must be added so a user auditing the cask knows the URL was verified by the Homebrew Cask team as the one provided by the vendor, even though it may look unofficial. It is our responsibility as Homebrew Cask maintainers to verify both the url and homepage information when first added (or subsequently modified, apart from versioning).

The parameter doesn’t mean you should trust the source blindly, but we only approve casks in which users can easily verify its authenticity with basic means, such as checking the official homepage or public repository. Occasionally, slightly more elaborate techniques may be used, such as inspecting a livecheck URL we established as official. Cases where such quick verifications aren’t possible (e.g. when the download URL is behind a registration wall) are treated in a stricter manner.

Difficulty Finding a URL

Web browsers may obscure the direct url download location for a variety of reasons. Homebrew Cask supplies a list_url_attributes_on_file script which can read extended file attributes to extract the actual source URL of most files downloaded by a browser on macOS. The script usually emits multiple candidate URLs; you may have to test each of them:

$(brew --repository homebrew/cask)/developer/bin/list_url_attributes_on_file <file>

Subversion URLs

In rare cases, a distribution may not be available over ordinary HTTP/S. Subversion URLs are also supported, and can be specified by appending the following key/value pairs to url:

key	value
using:	the symbol :svn is the only legal value
revision:	string identifying the subversion revision to download
trust_cert:	set to true to automatically trust the certificate presented by the server (avoiding an interactive prompt)

Git URLs

Artifacts also may be distributed via Git repositories. URLs that end in .git are automatically assumed to be Git repositories, and the following key/value pairs may be appended to url:

key	value
using:	the symbol :git is the only legal value
tag:	string identifying the Git tag to download
revision:	string identifying the Git revision to download
branch:	string identifying the Git branch to download
only_path:	path within the repository to limit the checkout to. If only a single directory of a large repository is required, using this option can significantly speed up downloads. If provided, artifact paths are relative to this path.

SourceForge/OSDN URLs

SourceForge and OSDN (formerly SourceForge.JP) projects are common ways to distribute binaries, but they provide many different styles of URLs to get to the goods.

We prefer URLs of this format:

https://downloads.sourceforge.net/<project_name>/<filename>.<ext>

Or, if it’s from OSDN, where <subdomain> is typically of the form dl or <user>.dl:

http://<subdomain>.osdn.jp/<project_name>/<release_id>/<filename>.<ext>

If these formats are not available, and the application is macOS-exclusive (otherwise a command-line download defaults to the Windows version) we prefer the use of this format:

https://sourceforge.net/projects/<project_name>/files/latest/download

Some Providers Block Command-line Downloads

Some hosting providers actively block command-line HTTP clients. Such URLs cannot be used in casks.

Other providers may use URLs that change periodically, or even on each visit (example: FossHub). While some cases could be circumvented, they tend to occur when the vendor is actively trying to prevent automated downloads, so we prefer to not add those casks to the main repository.

Using a Block to Defer Code Execution

Some casks—notably nightlies—have versioned download URLs but are updated so often that they become impractical to keep current with the usual process. For those, we want to dynamically determine url.

The Problem

In theory, one can write arbitrary Ruby code right in the cask definition to fetch and construct a disposable URL.

However, this typically involves an HTTP round trip to a landing site, which may take a long time. Because of the way Homebrew Cask loads and parses casks, it is not acceptable that such expensive operations be performed directly in the body of a cask definition.

Writing the Block

Similar to the preflight, postflight, uninstall_preflight, and uninstall_postflight blocks, the url stanza offers an optional block syntax:

url "https://handbrake.fr/nightly.php" do |page|
  file_path = page[/href=["']?([^"' >]*Handbrake[._-][^"' >]+\.dmg)["' >]/i, 1]
  file_path ? URI.join(page.url, file_path) : nil
end

You can also nest url do blocks inside url do blocks to follow a chain of URLs.

The block is only evaluated when needed, for example at download time or when auditing a cask. Inside a block, you may safely do things such as HTTP/S requests that may take a long time to execute. You may also refer to the @cask instance variable, and invoke any method available on @cask.

The block will be called immediately before downloading; its result value will be assumed to be a String (or a pair of a String and Hash containing parameters) and subsequently used as a download URL.

You can use the url stanza with either a direct argument or a block but not with both.

Example of using the block syntax: vlc-nightly.rb

Mixing Additional URL Parameters With the Block Syntax

In rare cases, you might need to set URL parameters like cookies or referer while also using the block syntax.

This is possible by returning a two-element array as a block result. The first element of the array must be the download URL; the second element must be a Hash containing the parameters.

Stanza: version

version, while related to the app’s own versioning, doesn’t have to follow it exactly. It is common to change it slightly so it can be interpolated in other stanzas, usually in url to create a cask that only needs version and sha256 changes when updated. This can be taken further, when needed, with Ruby String methods.

For example, instead of

version "1.2.3"
url "https://example.com/file-version-123.dmg"

we can use

version "1.2.3"
url "https://example.com/file-version-#{version.delete('.')}.dmg"

We can also leverage the power of regular expressions. So instead of

version "1.2.3build4"
url "https://example.com/1.2.3/file-version-1.2.3build4.dmg"

we can use

version "1.2.3build4"
url "https://example.com/#{version.sub(%r{build\d+}, '')}/file-version-#{version}.dmg"

version Methods

The examples above can become hard to read, however. Since many of these changes are common, we provide a number of helpers to clearly interpret otherwise obtuse cases:

method	input	output
major	1.2.3-a45,ccdd88	1
minor	1.2.3-a45,ccdd88	2
patch	1.2.3-a45,ccdd88	3-a45
major_minor	1.2.3-a45,ccdd88	1.2
major_minor_patch	1.2.3-a45,ccdd88	1.2.3-a45
minor_patch	1.2.3-a45,ccdd88	2.3-a45
before_comma	1.2.3-a45,ccdd88	1.2.3-a45
after_comma	1.2.3-a45,ccdd88	ccdd88
dots_to_hyphens	1.2.3-a45,ccdd88	1-2-3-a45,ccdd88
no_dots	1.2.3-a45,ccdd88	123-a45,ccdd88

Similar to dots_to_hyphens, we provide methods for all logical permutations of {dots,hyphens,underscores}_to_{dots,hyphens,underscores}. The same applies to no_dots in the form of no_{dots,hyphens,underscores}, with an extra no_dividers that applies all these at once.

Finally, there is csv which returns an array of comma-separated values. csv, before_comma and after_comma are extra-special to allow for otherwise complex cases, and should be used sparingly. There should be no more than two of , per version.

version :latest

The special value :latest is used when

• url does not contain any version information and there is no way to retrieve the version using a livecheck, or
• having a correct value for version is too difficult or impractical, even with our automated systems. For example, chromium.rb releases multiple versions a day.

Stanza: zap

zap Purpose

The zap stanza describes a more complete uninstallation of files associated with a cask. The zap procedures will never be performed by default, but only if the user uses --zap on uninstall:

brew uninstall --zap firefox

zap stanzas may remove:

• Preference files and caches stored within the user’s ~/Library directory.
• Shared resources such as application updaters. Since shared resources may be removed, other applications may be affected by brew uninstall --zap. Understanding that is the responsibility of the end user.

zap stanzas should not remove:

• Files created by the user directly.

Appending --force to the command will allow you to perform these actions even if the cask is no longer installed:

brew uninstall --zap --force firefox

zap Syntax

The form of the zap stanza follows the uninstall stanza. All the same directives are available. The trash: key is preferred over delete:.

Example: dropbox.rb

zap Creation

The simplest method is to use @nrlquaker's CreateZap, which can automatically generate the stanza. In a few instances it may fail to pick up anything and manual creation may be required.

Manual creation can be facilitated with:

• Some of the developer tools which are already available in Homebrew Cask.
• sudo find / -iname "*<search item>*"
• An uninstaller tool such as AppCleaner.
• Inspection of the usual paths, i.e. /Library/{'Application Support',LaunchAgents,LaunchDaemons,Frameworks,Logs,Preferences,PrivilegedHelperTools} and ~/Library/{'Application Support',Caches,Containers,LaunchAgents,Logs,Preferences,'Saved Application State'}.

---

Token reference

This section describes the algorithm implemented in the generate_cask_token script, and covers detailed rules and exceptions which are not needed in most cases.

• Purpose
• Finding the Simplified Name of the Vendor’s Distribution
• Converting the Simplified Name To a Token
• Cask Filenames
• Cask Headers
• Cask Token Examples
• Tap-Specific Cask Token Examples
• Special Affixes

Purpose

Software vendors are often inconsistent with their naming. By enforcing strict naming conventions we aim to:

• Prevent duplicate submissions
• Minimize renaming events
• Unambiguously boil down the name of the software into a unique identifier

Details of software names and brands will inevitably be lost in the conversion to a minimal token. To capture the vendor’s full name for a distribution, use the name within a cask. name accepts an unrestricted UTF-8 string.

Finding the Simplified Name of the Vendor’s Distribution

Simplified Names of Apps

• Start with the exact name of the application bundle as it appears on disk, such as Google Chrome.app.

• If the name uses letters outside A–Z, convert it to ASCII as described in Converting to ASCII.

• Remove .app from the end.

• Remove from the end: the string “app”, if the vendor styles the name like “Software App.app”. Exception: when “app” is an inseparable part of the name, without which the name would be inherently nonsensical, as in whatsapp.rb.

• Remove from the end: version numbers or incremental release designations such as “alpha”, “beta”, or “release candidate”. Strings which distinguish different capabilities or codebases such as “Community Edition” are currently accepted. Exception: when a number is not an incremental release counter, but a differentiator for a different product from a different vendor, as in kdiff3.rb.

• If the version number is arranged to occur in the middle of the App name, it should also be removed.

• Remove from the end: “Launcher”, “Quick Launcher”.

• Remove from the end: strings such as “Desktop”, “for Desktop”.

• Remove from the end: strings such as “Mac”, “for Mac”, “for OS X”, “macOS”, “for macOS”. These terms are generally added to ported software such as “MAME OS X.app”. Exception: when the software is not a port, and “Mac” is an inseparable part of the name, without which the name would be inherently nonsensical, as in PlayOnMac.app.

• Remove from the end: hardware designations such as “for x86”, “32-bit”, “ARM”.

• Remove from the end: software framework names such as “Cocoa”, “Qt”, “Gtk”, “Wx”, “Java”, “Oracle JVM”, etc. Exception: the framework is the product being casked.

• Remove from the end: localization strings such as “en-US”.

• If the result of that process is a generic term, such as “Macintosh Installer”, try prepending the name of the vendor or developer, followed by a hyphen. If that doesn’t work, then just create the best name you can, based on the vendor’s web page.

• If the result conflicts with the name of an existing cask, make yours unique by prepending the name of the vendor or developer, followed by a hyphen. Example: unison.rb and panic-unison.rb.

• Inevitably, there are a small number of exceptions not covered by the rules. Don’t hesitate to use the forum if you have a problem.

Converting to ASCII

• If the vendor provides an English localization string, that is preferred. Here are the places it may be found, in order of preference:

  • CFBundleDisplayName in the main Info.plist file of the app bundle
  • CFBundleName in the main Info.plist file of the app bundle
  • CFBundleDisplayName in InfoPlist.strings of an en.lproj localization directory
  • CFBundleName in InfoPlist.strings of an en.lproj localization directory
  • CFBundleDisplayName in InfoPlist.strings of an English.lproj localization directory
  • CFBundleName in InfoPlist.strings of an English.lproj localization directory

• When there is no vendor localization string, romanize the name by transliteration or decomposition.

• As a last resort, translate the name of the app bundle into English.

Simplified Names of pkg-based Installers

• The Simplified Name of a pkg may be more tricky to determine than that of an App. If a pkg installs an App, then use that App name with the rules above. If not, just create the best name you can, based on the vendor’s web page.

Simplified Names of non-App Software

• Currently, rules for generating a token are not well-defined for Preference Panes, QuickLook plugins, and several other types of software installable by Homebrew Cask. Just create the best name you can, based on the filename on disk or the vendor’s web page. Watch out for duplicates.

  Non-app tokens should become more standardized in the future.

Converting the Simplified Name To a Token

The token is the primary identifier for a package in this project. It’s the unique string users refer to when operating on the cask.

To convert the App’s Simplified Name (above) to a token:

• Convert all letters to lower case.
• Expand the + symbol into a separated English word: -plus-.
• Expand the @ symbol into a separated English word: -at-.
• Spaces become hyphens.
• Underscores become hyphens.
• Middots/Interpuncts become hyphens.
• Hyphens stay hyphens.
• Digits stay digits.
• Delete any character which is not alphanumeric or a hyphen.
• Collapse a series of multiple hyphens into one hyphen.
• Delete a leading or trailing hyphen.

Cask Filenames

Casks are stored in a Ruby file named after the token, with the file extension .rb.

Cask Headers

The token is also given in the header line for each cask.

Cask Token Examples

These illustrate most of the rules for generating a token:

App Name on Disk	Simplified App Name	Cask Token	Filename
Audio Hijack Pro.app	Audio Hijack Pro	audio-hijack-pro	audio-hijack-pro.rb
VLC.app	VLC	vlc	vlc.rb
BetterTouchTool.app	BetterTouchTool	bettertouchtool	bettertouchtool.rb
LPK25 Editor.app	LPK25 Editor	lpk25-editor	lpk25-editor.rb
Sublime Text 2.app	Sublime Text	sublime-text	sublime-text.rb

Tap-Specific Cask Token Examples

Cask taps have naming conventions specific to each tap.

• Homebrew/cask-versions
• Homebrew/cask-fonts

Special Affixes

A few situations require a prefix or suffix to be added to the token.

Token Overlap

When the token for a new cask would otherwise conflict with the token of an already existing cask, the nature of that overlap dictates the token, potentially for both casks. See Forks and Apps with Conflicting Names for information on how to proceed.

Potentially Misleading Name

If the token for a piece of unofficial software that interacts with a popular service would make it look official and the vendor is not authorised to use the name, a prefix must be added for disambiguation.

In cases where the prefix is ambiguous and would make the app appear official, the -unofficial suffix may be used.