Verb Aliasing

The catkin command allows you to define your own verb “aliases” which expand to more complex expressions including built-in verbs, command-line options, and other verb aliases. These are processed before any other command-line processing takes place, and can be useful for making certain use patterns more convenient.

The Built-In Aliases

You can list the available aliases using the --list-aliases option to the catkin command. Below are the built-in aliases as displayed by this command:

$ catkin --list-aliases
b: build
bt: b --this
ls: list
install: config --install

Defining Additional Aliases

Verb aliases are defined in the verb_aliases sub-directory of the catkin config folder, ~/.config/catkin/verb_aliases. Any YAML files in that folder (files with a .yaml extension) will be processed as definition files.

These files are formatted as simple YAML dictionaries which map aliases to expanded expressions, which must be composed of other catkin verbs, options, or aliases:

<ALIAS>: <EXPRESSION>

For example, aliases which configure a workspace profile so that it ignores the value of the CMAKE_PREFIX_PATH environment variable, and instead extends one or another ROS install spaces could be defined as follows:

# ~/.config/catkin/verb_aliases/10-ros-distro-aliases.yaml
extend-sys: config --profile sys --extend /opt/ros/indigo -x _sys
extend-overlay: config --profile overlay --extend ~/ros/indigo/install -x _overlay

After defining these aliases, one could use them with optional additional options and build a given configuration profile.

$ catkin extend-overlay
$ catkin profile set overlay
$ catkin build some_package

Note

The catkin command will initialize the verb_aliases directory with a file named 00-default-aliases.yaml containing the set of built-in aliases. These defaults can be overridden by adding additional definition files, but the default alias file should not be modified since any changes to it will be over-written by invocations of the catkin command.

Alias Precedence and Overriding Aliases

Verb alias files in the verb_aliases directory are processed in alphabetical order, so files which start with larger numbers will override files with smaller numbers. In this way you can override the built-in aliases using a file which starts with a number higher than 00-.

For example, the bt: build --this alias exists in the default alias file, 00-default-aliases.yaml, but you can create a file to override it with an alternate definition defined in a file named 01-my-aliases.yaml.

# ~/.config/catkin/verb_aliases/01-my-aliases.yaml
# Override `bt` to build with no deps
bt: build --this --no-deps

You can also disable or unset an alias by setting its value to null. For example, the ls: list alias is defined in the default aliases, but you can override it with this entry in a custom file named something like 02-unset.yaml:

# ~/.config/catkin/verb_aliases/02-unset.yaml
# Disable `ls` alias
ls: null

Recursive Alias Expansion

Additionally, verb aliases can be recursive, for instance in the bt alias, the b alias expands to build so that b --this expands to build --this. The catkin command shows the expansion of aliases when they are invoked so that their behavior is more transparent:

$ catkin bt
==> Expanding alias 'bt' from 'catkin bt' to 'catkin b --this'
==> Expanding alias 'b' from 'catkin b --this' to 'catkin build --this'
...