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I'm trying to open a file from terminal and ensure that line-wrap will be off. I'm trying the following code, but it won't work

emacs --no-window-system --eval '(setq truncate-lines 1)' file

I don't want to set it as default or to change init. Just to open this specific file without wraping lines.

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truncate-lines is buffer-local. To set the default for all buffers, use (setq-default truncate-lines t). Major-modes and minor-modes can reset this variable and it will be necessary to use a major-mode or minor-mode hook in that case, or directory-local variables, or file-local variables.

EXAMPLE [assumes we want to load a file with an extension of el, which will default to the emacs-lisp-mode]:

/path/to/emacs --no-window-system --eval "(add-hook 'emacs-lisp-mode-hook (lambda nil (setq truncate-lines t)))" /path/to/file.el

When the file loads, check the value with M-x describe-variable RET truncate-lines RET or C-h v.


EDIT:  In the commentary below, the O.P. has indicted that certain files may be opened in fundamental-mode because a particular file extension may not be associated with a major-mode. While it is possible to use file-local variables or directory-local variables, the O.P. has expressed a preference to handle this entirely on the command-line. One way to accomplish that is as follows:

/path/to/emacs --no-window-system --eval "(progn (find-file \"/path/to/file.csv\") (setq truncate-lines t))"

NOTE: find-file (with its underlying functions) set the buffer of the newly opened file as the current-buffer. When (setq truncate-lines t) is called subsequent to (find-file ...), it is applied to said current-buffer. If the target buffer did not have focus for whatever the reason (e.g., find-file-noselect), then it would be necessary to use something like (with-current-buffer ...) to ensure that truncate-lines is applied to the correct buffer.

  • [The O.P. has indicated briefly in a comment that was withdrawn that he/she wishes to open a file with a csv extension. My comment is in relation thereto.] A csv file extension is not associated with a recognized major-mode using Emacs without any configuration whatsoever. Would the O.P. prefer a file with a csv extension to be in any particular major-mode when the file gets opened in Emacs? Or, do you prefer fundamental-mode? If you prefer fundamental-mode, then you could use /path/to/emacs --no-window-system --eval "(setq-default truncate-lines t)" /path/to/file.csv – lawlist Jan 20 '18 at 20:27
  • The file opens in Fundamental mode, so I cannot use hooks. I'm trying to figure out some way of doing it. If you know, please help. – rvbarreto Jan 20 '18 at 20:33
  • If you don't mind using (setq-default ...), then the example in the previous comment does the job. Otherwise, consider using file-local or directory-local variables ... – lawlist Jan 20 '18 at 20:34
  • The problem is that the code will run in a server by a lot of different users and I don't want my code to be invasive and change their emacs defaults – rvbarreto Jan 20 '18 at 20:35
  • How about wrapping your find-file function inside the function that sets the truncate-lines variable? /path/to/emacs --no-window-system --eval "(progn (find-file \"/path/to/file.csv\") (setq truncate-lines t))" This example assumes that the target buffer is set by find-file so that truncate-lines is set locally in that buffer which has focus. Depending upon the complexity of the function being run, we could use (with-current-buffer ....) – lawlist Jan 20 '18 at 20:42

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