When the minibuffer offers tab completion, how can I make that case-insensitive?
Preferably a global setting that makes any completion – a filename, a command, ido, etc. – obey that setting.
Sure. Set variable
t. Put this in your init file:
(setq completion-ignore-case t)
C-h v completion-ignore-case:
completion-ignore-caseis a variable defined in
C source code.
Its value is
nilmeans don't consider case significant in completion.
For file-name completion,
read-file-name-completion-ignore-casecontrols the behavior, rather than this variable.
For buffer name completion,
read-buffer-completion-ignore-casecontrols the behavior, rather than this variable.