This section describes how to configure the contents and format of the package list, status line, and header line, as well as the output of aptitude search.

The format of each of these locations is defined by a “format string”. A format string is a string of text containing %-escapes such as %p, %S, and so on. The resulting output is created by taking the text and replacing the %-escapes according to their meanings (given below).

A %-escape can either have a fixed size, in which case it is always replaced by the same amount of text (with extra space characters added to fill it out as necessary), or it can be “expandable”, meaning that it takes up the space that is not claimed by fixed-size columns. If there are several expandable columns, the extra space is divided evenly between them.

All %-escapes come with a default size and/or expandability. The size of a %-escape can be changed by writing it between the % and the character identifying the escape; for instance, %20V generates the candidate version of the package, 20 characters wide. Placing a question mark (?) between the % and the character identifying the escape causes the column's “basic” width to vary depending on its content. Note that the resulting columns might not line up vertically!

If you want a particular %-escape to be expandable, even though it normally has a fixed width, place a pound sign (ie, “#”) immediately after it. For instance, to display the candidate version of a package, no matter how long it is, use the format string %V#. You can also place # after something that is not a %-escape; aptitude will “expand” the text preceding the # by inserting extra spaces after it.

In summary, the syntax of a %-escape is:

%[width][?]code[#]

The configuration variables Aptitude::UI::Package-Display-Format, Aptitude::UI::Package-Header-Format, and Aptitude::UI::Package-Status-Format define the default formats the package list, the header at the top of the package list, and the status line below the package list respectively. To change how the results of an aptitude search command are displayed, use the -F option.

The following %-escapes are available in format strings:

	Note
	Some of the descriptions below refer to “the package”. In the GUI, this is either the package being displayed or the currently selected package; in the command-line search, this is the package being displayed.

The package hierarchy is generated by a grouping policy: rules describing how the hierarchy should be built. The grouping policy describes a “pipeline” of rules; each rule can discard packages, create sub-hierarchies in which packages reside, or otherwise manipulate the tree. The configuration items Aptitude::UI::Default-Grouping and Aptitude::UI::Default-Preview-Grouping set the grouping policies for newly created package lists and preview screens, respectively. You can set the grouping policy for the current package list by pressing G.

The grouping policy is described by a comma-separated list of rules: rule1,rule2,.... Each rule consists of the name of the rule, possibly followed by arguments: for instance, versions or section(subdir). Whether arguments are required and how many arguments are required (or allowed) depends on the type of rule.

Rules can be non-terminal or terminal. A non-terminal rule will process a package by generating some part of the hierarchy, then passing the package on to a later rule. A terminal rule, on the other hand, will also generate part of the tree (typically items corresponding to the package), but does not pass its package to a later rule. If no terminal rule is specified, aptitude will use the default rule, which is to create the standard “package items”.

By default, packages in the package list or in the output of aptitude search are sorted by name. However, it is often useful to sort them according to different criteria (for instance, package size), and aptitude allows you to do just that by modifying the sorting policy.

Like the grouping policy described in the previous section, the sorting policy is a comma-separated list. Each item in the list is the name of a sorting rule; if packages are “equal” according to the first rule, the second rule is used to sort them, and so on. Placing a tilde character (~) in front of a rule reverses the usual meaning of that rule. For instance, priority,~name will sort packages by priority, but packages with the same priority will be placed in reverse order according to name.

To change the sorting policy for an active package list, press S. To change the default sorting for all package lists, set the configuration option Aptitude::UI::Default-Sorting. To change the sorting policy for aptitude search, use the --sort command-line option.

The available rules are: