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Cask Language Reference

This document acts as a complete specification, and covers aspects of the Cask Domain-Specific Language (DSL) which are not needed in most cases.

Casks Are Ruby Blocks

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 :v1 => 'alfred' do
  version '2.7.1_387'
  sha256 'a3738d0513d736918a6d71535ef3d85dd184af267c05698e49ac4c6b48f38e17'

  url "https://cachefly.alfredapp.com/Alfred_#{version}.zip"
  name 'Alfred'
  homepage 'http://www.alfredapp.com/'
  license :freemium

  app 'Alfred 2.app'
  app 'Alfred 2.app/Contents/Preferences/Alfred Preferences.app'

  postflight do
    suppress_move_to_applications :key => 'suppressMoveToApplications'
  end
end

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.

Required Stanzas

Each of the following stanzas is required for every Cask.

name multiple occurrences allowed? value
version no application version; give value of :latest if versioned downloads are not offered
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. (see also Checksum Stanza Details)
url no URL to the .dmg/.zip/.tgz/.tbz2 file that contains the application. A comment should be added if the hostnames in the url and homepage stanzas differ (see also URL Stanza Details)
homepage no application homepage; used for the brew cask home command
license no a symbol identifying the license category for the application. (see also License Stanza Details)

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 linked into the ~/Applications folder on installation (see also App Stanza Details)
pkg yes relative path to a .pkg file containing the distribution (see also Pkg Stanza Details)
binary yes relative path to a binary that should be linked into the /usr/local/bin folder on installation
colorpicker yes relative path to a ColorPicker plugin that should be linked into the ~/Library/ColorPickers folder on installation
font yes relative path to a font that should be linked into the ~/Library/Fonts folder on installation
input_method yes relative path to a input method that should be linked into the ~/Library/Input Methods folder on installation
internet_plugin yes relative path to a service that should be linked into the ~/Library/Internet Plug-Ins folder on installation
prefpane yes relative path to a preference pane that should be linked into the ~/Library/PreferencePanes folder on installation
qlplugin yes relative path to a QuickLook plugin that should be linked into the ~/Library/QuickLook folder on installation
screen_saver yes relative path to a Screen Saver that should be linked into the ~/Library/Screen Savers folder on installation
service yes relative path to a service that should be linked into the ~/Library/Services folder on installation
suite yes relative path to a containing directory that should be linked into the ~/Applications folder on installation (see also Suite Stanza Details)
artifact yes relative path to an arbitrary path that should be symlinked on installation. This is only for unusual cases. The app stanza is strongly preferred when linking .app bundles.
installer yes describes an executable which must be run to complete the installation. (see Installer Stanza Details)
stage_only no true. Assert that the Cask contains no activatable artifacts.

Optional Stanzas

name multiple occurrences allowed? value
name yes a string providing the full and proper name defined by the vendor (see also Name Stanza Details)
uninstall yes procedures to uninstall a Cask. Optional unless the pkg stanza is used. (see also Uninstall Stanza Details)
zap yes additional procedures for a more complete uninstall, including user files and shared resources. (see also Zap Stanza Details)
appcast no a URL providing an appcast feed to find updates for this Cask. (see also Appcast Stanza Details)
depends_on yes a list of dependencies and requirements for this Cask (see also Depends_on Stanza Details)
conflicts_with yes a list of conflicts with this Cask (not yet functional see also Conflicts_with Stanza Details)
caveats yes a string or Ruby block providing the user with Cask-specific information at install time (see also Caveats Stanza Details)
preflight yes a Ruby block containing preflight install operations (needed only in very rare cases)
postflight yes a Ruby block containing postflight install operations (see also Postflight Stanza Details)
uninstall_preflight yes a Ruby block containing preflight uninstall operations (needed only in very rare cases)
uninstall_postflight yes a Ruby block containing postflight uninstall operations
accessibility_access no true if the application should be granted accessibility access
container :nested => no relative path to an inner container that must be extracted before moving on with the installation; this allows us to support dmg inside tar, zip inside dmg, etc.
container :type => no a 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)
tags no a list of key-value pairs for Cask annotation. Not free-form. (see also Tags Stanza Details)
gpg no stub: not yet functional. (see also GPG Stanza Details)

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.release macports.rb, coconutbattery.rb
Hardware::CPU.is_32_bit? vuescan.rb
Hardware::CPU.is_64_bit? none, see Always Fall Through to the Newest Case

Version Comparisons

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

if MacOS.release <= :mavericks     # symbolic name
if MacOS.release <= '10.9'         # version string

The available symbols for OS X versions are: :cheetah, :puma, :jaguar, :panther, :tiger, :leopard, :snow_leopard, :lion, :mountain_lion, :mavericks, :yosemite, and :el_capitan. The corresponding numeric version strings should given as major releases containing a single dot.

Always Fall Through to the Newest Case

Conditionals should be constructed so that the default is the newest OS version or hardware type. 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 is released. Example (from coconutbattery.rb):

if MacOS.release <= :tiger
  # ...
elsif MacOS.release <= :snow_leopard
  # ...
else
  # ...
end

Header Line Details

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

cask <dsl-version> => '<cask-token>' do

<dsl-version> identifies the version of the Cask DSL, currently :v1.

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

The header line is not entirely strict Ruby: no comma is required after the Cask token.

There are currently some arbitrary limitations on Cask tokens which are in the process of being removed. The Travis bot will catch any errors during the transition.

Name Stanza Details

name stanza accepts a UTF-8 string defining the full name of the software.

If there are useful alternate names, name can be repeated multiple times. (Or, equivalently, an array value may be given.)

When multiple names are given, the first should follow the canonical branding as defined by the vendor.

Caveats Stanza Details

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 all staged Casks, typically /opt/homebrew-cask/Caskroom (only available with block form)
staged_path the staged location for this Cask, including version number, eg /opt/homebrew-cask/Caskroom/adium/1.5.10 (only available with block form)

Example:

caveats "Using #{token} is 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
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 software has been officially discontinued upstream
free_license(web_page) users may get an official license to use the software at web_page

Example:

caveats do
  path_environment_variable '/usr/texbin'
end

Checksum Stanza Details

Calculating the SHA256

The sha256 value is usually calculated by the command

$ shasum -a 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.

URL Stanza Details

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 HTTP/S 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
:using the symbol :post is the only legal value
:cookies a hash of cookies to be set in the download request
:referer a string holding the URL to set as referrer in the download request
:user_agent a 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 a hash of parameters to be set in the POST request

Example of using :cookies: java.rb

Example of using :referer: rrootage.rb

When URL and Homepage Hostnames Differ, Add a Comment

When the hostnames of url and homepage differ, the discrepancy should be documented with a comment of the form:

# URL_HOSTNAME is the official download host per the vendor homepage

Examples can be seen in visit.rb and vistrails.rb.

These comments must be added so a user auditing the cask knows the URL is the one provided by the vendor, even though it may look unofficial or suspicious. 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 exception to this rule is a homepage of github.io with a url of github.com, since we know this pair of hostnames is connected.

Difficulty Finding a URL

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

$ ./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 a 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)

Appcast Stanza Details

The value of the appcast stanza is a string, holding the URL for an appcast which provides information on future updates. Generally, the appcast URL returns Sparkle-compatible XML, though that is not required.

Example: adium.rb

Additional Appcast Parameters

key value
:sha256 a string holding the SHA-256 checksum of the most recent appcast which matches the current Cask versioning
:format a symbol describing the appcast format. One of: :sparkle, :plaintext, :unknown, where :sparkle is the default.

License Stanza Details

The license stanza is not free-form. A single value must be chosen from a list of valid symbols.

The values for license are categories, rather than fully-specified licenses. For example, :gpl is a category; we do not distinguish between versions of the GPL. Similarly, :cc and :bsd comprise many variants. They must always pertain to the license of the software itself, not the vendor’s business model (a free app to access a paid service is still :gratis, not :freemium).

The license stanza is intended as an aid to search/filtering of Casks. For full and complete information, the user must always rely on the vendor’s homepage.

Note that brew cask search and brew cask list are not yet capable of using the information stored in the license stanza.

Generic Category Licenses

Cask authors should use the most specific license category which is also correct. Generic categories are provided for difficult cases. :unknown is also perfectly fine if you are unsure.

Example: Chromium includes code with multiple licenses, all of which are open source. Chromium licensing is described by the generic category :oss.

symbol meaning
:oss open-source software
:closed closed-source software
:unknown license unknown
:other license is known, but fits no category

Valid Licenses

symbol generic category meaning URL
:gratis :closed free-to-use, closed source
:commercial :closed not free to use
:freemium :closed free-to-use, payment required for full or additional functionality http://en.wikipedia.org/wiki/Freemium
:affero :oss Affero General Public License https://gnu.org/licenses/agpl.html
:apache :oss Apache Public License http://www.apache.org/licenses/
:arphic :oss Arphic Public License http://www.arphic.com/tw/download/public_license.rar
:artistic :oss Artistic License http://dev.perl.org/licenses/artistic.html
:bsd :oss BSD License http://www.linfo.org/bsdlicense.html
:cc :oss Creative Commons License http://creativecommons.org/licenses/
:eclipse :oss Eclipse Public License https://www.eclipse.org/legal/eplfaq.php
:gpl :oss GNU Public License http://www.gnu.org/copyleft/gpl.html
:isc :oss Internet Systems Consortium License http://www.isc.org/downloads/software-support-policy/isc-license/
:lppl :oss LaTeX Project Public License http://latex-project.org/lppl/
:ncsa :oss University of Illinois/NCSA Open Source License http://otm.illinois.edu/uiuc_openSource
:mit :oss MIT License http://opensource.org/licenses/MIT
:mpl :oss Mozilla Public License https://www.mozilla.org/MPL/
:ofl :oss SIL Open Font License http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=OFL
:public_domain :oss not copyrighted http://creativecommons.org/publicdomain/zero/1.0/legalcode
:ubuntu_font :oss Ubuntu Font License http://font.ubuntu.com/licence/
:x11 :oss X Consortium License http://www.xfree86.org/3.3.6/COPYRIGHT2.html

Tags Stanza Details

The tags stanza is not free-form. The key-value pairs are limited to a list of valid keys. All tags keys accept string values.

The tags stanza is intended as an aid to search/filtering of Casks. For detailed information, the user must rely on the vendor’s homepage.

Note that brew cask search and brew cask list are not yet capable of using the information stored in the tags stanza.

Valid Tag Keys

key meaning
:vendor the full-text official name of the producer of the software: an author or corporate name, as appropriate. As the value is intended as a search target, commonly shared abbreviations such as Dr. or Inc. should be omitted. (example google-chrome.rb)

GPG Stanza Details

This is a stub for upcoming functionality, and is not fully documented.

The gpg stanza contains signature information for GPG-signed distributions. The form is:

gpg <signature>, <parameter> => <value>

where <parameter> is one of :key_id or :key_url, and <signature> points to the detached signature of the distribution. Commonly, the signature follows the url value. Example: libreoffice.rb.

App Stanza Details

In the simple case of a string argument to app, a symlink is created in the target ~/Applications directory using the same basename as the source file. For example:

app 'Alfred 2.app'

causes the creation of this symlink:

~/Applications/Alfred 2.app

which points to a source file such as:

/opt/homebrew-cask/Caskroom/alfred/2.1.1_227/Alfred 2.app

Renaming the Target

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

app 'eclipse/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 manopen.rb):

artifact 'openman.1', :target => '/usr/local/share/man/man1/openman.1'

:target Works on Most Artifact Types

The :target key works similarly for most Cask artifacts, such as app, binary, colorpicker, font, input_method, prefpane, qlplugin, service, suite, 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'). With app, use it when it makes sense functionally and document your reason cleary in the Cask: was it for clarity; for consistency; to prevent conflicts? With binary you can take some extra liberties to be consistent with other command-line tools, like changing case or removing an extension.

Suite Stanza Details

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 2015'

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

Pkg Stanza Details

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

pkg 'Unity.pkg'

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

  • :allow_untrusted — pass -allowUntrusted to /usr/sbin/installer

Example:

pkg 'Soundflower.pkg', :allow_untrusted => true

Installer Stanza Details

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:

installer :manual => 'Little Snitch Installer.app'

Installer :script

installer :script introduces a series of key-value pairs describing a command which will automate completion of the install. The form is similar to uninstall :script:

key value
:script path to an install script to be run via sudo. (Required first key.)
: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 false if the script does not need sudo

The path may be absolute, or relative to the Cask. Example:

installer :script => 'Adobe AIR Installer.app/Contents/MacOS/Adobe AIR Installer',
          :args => %w[-silent]

Depends_on Stanza Details

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 use: SSHFS depends on OSXFUSE.

depends_on :cask => 'osxfuse'

Depends_on :formula

The value should name a Homebrew Formula needed by the Cask.

Example use: 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 Homebrew Formula unar:

depends_on :formula => 'unar'

Depends_on :macos

Requiring an Exact OS X Release

The value for depends_on :macos may be a symbol, string, or an array, listing the exact compatible OS X releases.

The available values for OS X releases are:

symbol corresponding string
:cheetah '10.0'
:puma '10.1'
:jaguar '10.2'
:panther '10.3'
:tiger '10.4'
:leopard '10.5'
:snow_leopard '10.6'
:lion '10.7'
:mountain_lion '10.8'
:mavericks '10.9'
:yosemite '10.10'
:el_capitan '10.11'

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

depends_on :macos => :yosemite
depends_on :macos => [:mavericks, :yosemite]
depends_on :macos => '10.9'
depends_on :macos => ['10.9', '10.10']

Setting a Minimum OS X Release

depends_on :macos can also accept a string starting with a comparison operator such as >=, followed by an OS X release in the form above. The following are both valid expressions meaning “at least OS X 10.9”:

depends_on :macos => '>= :mavericks'
depends_on :macos => '>= 10.9'

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 value matches the user’s hardware.

The available symbols for hardware are:

symbol meaning
:i386 32-bit Intel
:x86_64 64-bit Intel
:ppc_7400 32-bit PowerPC
:ppc_64 64-bit PowerPC
:intel Any Intel
:ppc Any PowerPC

The following are all valid expressions:

depends_on :arch => :x86_64
depends_on :arch => [:x86_64]          # same meaning as above
depends_on :arch => :intel
depends_on :arch => [:i386, :x86_64]   # same meaning as above

Since PowerPC hardware is no longer common, the expression most frequently needed will be:

depends_on :arch => :x86_64

All Depends_on Keys

key description
:formula a Homebrew Formula
:cask a Cask token
:macos a symbol, string, array, or comparison expression defining OS X release requirements.
:arch a symbol or array defining hardware requirements.
:x11 a Boolean indicating a dependency on X11.
:java stub - not yet functional

conflicts_with Stanza Details

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

Several keys are accepted by conflicts_with, but none of them are yet enforced by the backend implementation. It is fine to proactively add conflicts_with stanzas to Casks in anticipation of future backend support; they are currently just a type of structured comment.

key description
:formula stub - not yet functional
:cask stub - not yet functional
:macos stub - not yet functional
:arch stub - not yet functional
:x11 stub - not yet functional
:java stub - not yet functional

Uninstall Stanza Details

IF YOU CANNOT DESIGN A WORKING UNINSTALL STANZA, PLEASE SUBMIT YOUR CASK ANYWAY. The maintainers will help you write an uninstall stanza, just ask!

uninstall :pkgutil Is The Easiest and Most Useful

:pkgutil is the easiest and most useful uninstall directive. See Uninstall Key :pkgutil.

uninstall Is Required for Casks That Install a pkg

For most Casks, uninstall actions are determined automatically, and an explicit uninstall stanza is not needed. However, a Cask which uses the pkg stanza will not know how to uninstall correctly unless an uninstall stanza is given.

So, while the Cask language does not enforce the requirement, it is much better for end-users if every pkg 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 launchctl 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 (used when :quit does not work)
  • :kext (string or array) - bundle ids of kexts to unload from the system
  • :pkgutil (string, regexp or array of strings and regexps) - strings or regexps matching bundle ids of packages to uninstall using pkgutil
  • :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 false if the script does not need sudo
  • :delete (string or array) - single-quoted, absolute paths of files or directory trees to remove. :delete should only be used as a last resort. :pkgutil is strongly preferred
  • :rmdir (string or array) - single-quoted, absolute paths of directories to remove if empty.
  • :trash (string or array) - currently a synonym for :delete. In the future this will cause files to be moved to the 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.

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

Uninstall Key :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 the command:

$ ./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 the command:

$ ./developer/bin/list_pkg_ids_by_regexp <regular-expression>

List Files Associated With a pkg Id

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

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

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

Uninstall Key :launchctl

IDs for currently loaded launchctl jobs can be listed using the command:

$ ./developer/bin/list_loaded_launchjob_ids

IDs for all installed launchctl jobs can be listed using the command:

$ ./developer/bin/list_installed_launchjob_ids

Uninstall Key :quit

Bundle IDs for currently running Applications can be listed using the command:

$ ./developer/bin/list_running_app_ids

Bundle IDs inside an Application bundle on disk can be listed using the command:

$ ./developer/bin/list_ids_in_app </path/to/application.app>

Uninstall Key :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 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 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 which 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 Key :kext

IDs for currently loaded kernel extensions can be listed using the command:

$ ./developer/bin/list_loaded_kext_ids

IDs inside a kext bundle you have located on disk can be listed using the command:

$ ./developer/bin/list_id_in_kext </path/to/name.kext>

Uninstall Key :delete

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

Arguments to uninstall :delete should be static, single-quoted, absolute paths.

  • Only single quotes should be used.
  • Double-quotes should not be used. ENV['HOME'] and other variables should not be interpolated in the value.
  • Only absolute paths should be given.
  • No glob expansion is performed (eg * characters are literal), though glob expansion is a desired future feature.

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

Uninstall Key :trash

stub - currently a synonym for :delete. In the future this will cause files to be moved to the Trash. It is best not to use this stub until it gains the proper functionality.

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 the command:

$ ./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 the command:

$ ./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 the command:

$ ./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.

*flight Stanzas Details

Evaluation of Blocks is Always Deferred

The Ruby blocks defined by preflight, postflight, uninstall_preflight, and uninstall_postflight 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
plist_set(key, value) preflight, postflight, uninstall_preflight set a value in the Info.plist file for the app bundle. Example: rubymine.rb
set_ownership(paths) preflight, postflight, uninstall_preflight set user and group ownership of paths. Example: unifi-controller.rb
set_permissions(paths, permissions_str) preflight, postflight, uninstall_preflight set permissions in paths to permissions_str Example: docker-machine.rb
suppress_move_to_applications postflight suppress a dialog asking the user to move the app to the /Applications folder. Example: github.rb.

plist_set currently has the limitation that it only operates on the bundle indicated by the first app stanza (and the Cask must contain an app stanza).

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').

suppress_move_to_applications optionally accepts a :key parameter for apps which use a nonstandard defaults key. Example: alfred.rb.

Zap Stanza Details

Zap Stanza Purpose

The zap stanza describes a more complete uninstallation of resources associated with a Cask. The zap procedures will never be performed by default, but only if the user invokes the zap verb:

$ brew cask zap td-toolbelt             # also removes org.ruby-lang.installer

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 cask zap. Understanding that is the responsibility of the end user.

zap stanzas should not remove:

  • Files created by the user directly.

Zap Stanza Syntax

The form of zap stanza follows the uninstall stanza. All of the same directives are available.

zap differs from uninstall in the following ways:

  • The use of :delete is not discouraged.
  • The target values for :delete and :rmdir accept leading tilde characters (~), which will be expanded to home directories.

Example: injection.rb

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 :v1 => 'myapp' do
  module Utils
    def self.arbitrary_method
      ...
    end
  end

  name 'MyApp'
  version '1.0'
  sha256 'a32565cdb1673f4071593d4cc9e1c26bc884218b62fef8abc450daa47ba8fa92'
  license :unknown

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

This should be used sparingly: any method which is needed by two or more Casks should instead be rolled into the core. 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.

Revisions to the Cask DSL

The Cask DSL is being revised and stabilized. Changes are tracked in cask_language_deltas.md.

<3 THANK YOU TO ALL CONTRIBUTORS! <3