Fixing forced indentation in shell-script-mode for tcsh

Question

How do you configure the indentation to work correctly for tcsh shell scripts?

I am unable to make the indentation work correctly when I use the shell-script-mode as it is.

Problem: An indentation of 4 spaces is inserted when I hit enter (when there shouldn't be any indentation!)

How to reproduce this problem?

• Open \emacs -q&
• Type #!/bin/tcsh -f in an empty buffer and save it as something like a.csh so that the shell-script-mode is auto-loaded.

When you hit enter at the end of this first and only line, the buffer converts from

#!/bin/tcsh -f (no indentation)

to

    #!/bin/tcsh -f (with indentation)

I am on the stable 24.4 version of emacs.

Answer 1

Finally found a fix with a bit of a hack with the help of edebug-defun!

The keyword highlighting of shell-script-mode is good. But the problem was that it set the indent-line-function to sh-basic-indent-line when sh-shell was set to tcsh. That function caused the extra indentation by 4 spaces.

There is an outdated csh-mode.el (last updated in 1999) which does the indentation well but has outdated keyword highlighting info.

So I simply borrowed the useful stuff (csh-indent-line and csh-indent-region functions) from csh-mode.el when I am editing a .alias or any file whose extension ends in *csh:

(defun my/tcsh-set-indent-functions ()
  (when (or (string-match ".*\\.alias" (buffer-file-name))
            (string-match ".*csh$" (file-name-extension (buffer-file-name))))
    (require 'csh-mode) ; https://github.com/Tux/tcsh/blob/master/csh-mode.el
    (setq-local indent-line-function 'csh-indent-line)
    (setq-local indent-region-function 'csh-indent-region)))
(add-hook 'sh-set-shell-hook #'my/tcsh-set-indent-functions)

Answer 2

By default, emacs 24.4 turns on electric-indent-mode which makes it indent automatically. Disable it and you won't have that problem anymore:

(add-hook 'after-change-major-mode-hook (lambda() (electric-indent-mode -1)))

I set newline-and-indent to RET globally and have no problem:

(global-set-key (kbd "RET") 'newline-and-indent)

Answer 3

Going off the answer by Kaushal Modi this is a more general solution that will use the csh-indentation anytime your shell file is set to tcsh or csh. That way you don't have to enumerate every file that you want this fix to apply to and it won't affect other shell types.

(defun my/tcsh-set-indent-functions ()
  (when (string-match ".*csh.*" (symbol-value 'sh-shell-file))
    (require 'csh-mode) ; https://github.com/Tux/tcsh/blob/tux/csh-mode.el
    (setq-local indent-line-function 'csh-indent-line)
    (setq-local indent-region-function 'csh-indent-region)))
(add-hook 'sh-set-shell-hook #'my/tcsh-set-indent-functions)