The radare2 search engine can be configured through several configuration variables, modifiable with e command.
e cmd.hit = x ; radare2 command to execute on every search hit
e search.distance = 0 ; search string distance
e search.in = [foo] ; search scope limit. Supported values: raw, block, file, section
e search.align = 4 ; only show search results aligned by specified boundary.
e search.from = 0 ; start address
e search.to = 0 ; end address
e search.asmstr = 0 ; search for string instead of assembly
e search.flags = true ; if enabled, create flags on hits
The search.align variable is used to limit valid search hits to certain alignment. For example, with e search.align=4 you will see only hits found at 4-bytes aligned offsets.
The search.flags boolean variable instructs the search engine to flag hits so that they can be referenced later. If a currently running search is interrupted with Ctrl-C keyboard sequence, current search position is flagged with "search_stop".