How to code a command to `write-region` to a particular file?

Question

I have a system that I am not allowed permissions to install software but need to copy text from the remote server to the host computer's system clipboard. Because I can't install xclip or xsel and I am using emacs with tmux, the formatting of text gets all screwed up because of the newlines that tmux introduces. I thought of the possibility of writing regions to a file that I can remotely open the file and manually copy the properly formatted text.

I've created my own keyboard defined macro using write-regions that worked during a current open session of emacs but would have problems upon reopening. Error along the lines of command terminated by ringing the bell.

I've also used the following answer's code but the OP wanted to interactively set the file but in my case the file is known already so there is no need for me to set it each time I use the function.

Is there a way for me to write this function such that the a region automatically writes to ~/copybuffer.txt and doesn't delete the region afterwards. See original QA here and my code edits.

Unfortunately, in my code I see variable is void: start. I clearly don't understand something about defining lisp functions.

(defun copybuffer
  "function takes current region, and writes it to specified file"
  (write-region region-beginning region-end '~/copybuffer.txt' t)))

Answer 1

It's only you're having syntax issues, try this:

(defun copybuffer ()
  "function takes current region, and writes it to specified file"
  (interactive)
  (write-region (region-beginning) (region-end) "~/copybuffer.txt"))

Summary:

• region-beginning and region-end are functions, so they have to be between parenthesis to be recognized as functions.
• start and end should be variables which you haven't defined in your code, so I used region's limits, which should fit the bill in this case.
• copybuffer didn't conform to the function definition syntax, and was closed early after write-region.
• Added interactiveto be able to call it with M-x.
• Removed t as this is an optional argument that appends to file instead of overwrites

Take a look to the elisp intro: C-h i m Emacs elisp intro.