Making tcsh history isearch case-insensitive

Question

How do I make tcsh's history isearch (ctrl-r) case insensitive? I tried "set complete=igncase" but that affects file completion, not history isearch.

Answer 1

History search in tcsh always looks for an exact match (both incremental and nonincremental)¹. If you want a case-insensitive search, code it yourself, or make a feature request — but don't hold your breath, tcsh hasn't been actively developed for years.

I recommend switching to zsh, where incremental search is case-insensitive by default.

¹ _{As of tcsh 6.17.02. See c_search_line and e_inc_search in ed.chared.c.}