Comint mode is a package that defines a general command-interpreter-in-a-buffer. The idea is that you can build specific process-in-a-buffer modes on top of comint mode – e.g., lisp, shell, scheme, T, soar, …. This way, all these specific packages share a common base functionality, and a common set of bindings, which makes them easier to use (and saves code, implementation time, etc., etc.).
Find examples of ComintModes.
Since SqlMode is based on comint-mode, several aspects of SQLi buffers can be controlled by setting comint variables: automatically truncate buffers to a certain size, size of the input ring (history). You can either set these variables globally in your .emacs (in which case they will affect other modes such as shell-mode), or you can set these variables on a sql-interactive-mode-hook:
(add-hook 'sql-interactive-mode-hook (function (lambda () (setq comint-output-filter-functions 'comint-truncate-buffer comint-buffer-maximum-size 5000 comint-scroll-show-maximum-output t comint-input-ring-size 500))))
If you are using Emacs 20, take a look at ComintPatched if you are interested in recovering multiline statements from the history.
Lots of times, the buffer just grows and grows, especially if you do a lot of commands in shell mode. If I’m doing interative work like looking through repeated find results, I clear the buffer constantly so C-a C-s will search through only what I care about.
(defun cmg:shell-clear-region () (interactive) (delete-region (point-min) (point-max)) (comint-send-input))
You can use Icicles completion in Comint mode. Whenever there are multiple completion candidates, Icicles completion is used (if Icicle minor mode is on). This means you can cycle to choose a candidate, complete using one or more substrings or regexps (progressive completion), and so on. See Icicles - Completion in Comint Modes.
You can also use `
C-`’ to quickly find, reuse, and edit a previous shell input, matching it in several ways. See Icicles - Reuse Comint Inputs.
Here’s a couple of functions that I find useful for comint buffers.
(defun comint-jump-to-input-ring () "Jump to the buffer containing the input history." (interactive) (progn (comint-dynamic-list-input-ring) (other-window 1)))
(defun comint-goto-first-input nil "Move the command history back to the first input." (interactive) (if comint-input-ring-index (comint-previous-input (- comint-input-ring-index))))
You can bind them to keys by adding them to the comint-mode-hook like this:
(add-hook 'comint-mode-hook (function (lambda () (local-set-key (kbd "C-<f7>") 'comint-jump-to-input-ring) (local-set-key (kbd "C-<") 'comint-goto-first-input))))