$ vi ’grep -l pattern files' lets you edit with vi, all the files matching that grep pattern. For example, this is useful for editing all files of a project,

$ vi ’grep -l pattern files' lets you edit with vi, all the files matching that grep pattern. For example, this is useful for editing all files of a project, which contain a particular variable name, in order to change that name to something else everywhere it is used. The single quotes in the command should actually be backward single quotes, which I don't have on my mobile keyboard right now.