To do an eyeball search is to look for something specific in a mass of code or data with one's own native optical sensors, as opposed to using some sort of pattern matching software like grep or any other automated search tool. Also known as vgrep or ogrep, i.e., "visual/optical grep", and in the IBM mainframe world as IEBIBALL.
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<jargon> /vee'grep/ (Or "optical grep") Visual grep. Finding patterns in a file by eye rather than digitally. Compare vdiff. [Jargon File] (1998-02-06)