iCab Mobile has a list of known search engines, which you can also expand yourself. When the address field is activated, the icon of the currently set default search engine is displayed, which you can change by tapping the icon.
Each search engine can be assigned a shortcut string. If you enter this shortcut first in the address field, followed by a space and the search term, the search engine specified by the shortcut is used for the search. This makes it very easy to specify the search engine without having to change the default search engine.
Searches in private tabs are never saved in the search history, nor are searches that take place when private mode is active.
The URL for the search engines must be the URL that is also used for the actual search requests. The placeholder '%@' can be used in the URL, which is then later replaced by the real search term. If this placeholder is missing, iCab appends the search term to the end of the URL during a search. This means that when defining the URL manually, you must ensure that this URL corresponds exactly to what the search engine expects and can process in both cases.
In general you can also add new search engines (or search features of websites) to the list of search engines via the context menu and the menu item Save as search engine. iCab automatically determines this URL so that you do not have to enter it manually. To do this, you must visit exactly the website that contains the search field so that iCab can automatically determine the necessary parameters.