Emacs Lisp: Write File

Write File

write-region

(write-region START END FILENAME &optional APPEND VISIT LOCKNAME MUSTBENEW)

Write region or string to a file.

• START and END are buffer positions.
• If START is nil, write whole buffer. END is ignored.
• If START is a string, write that. END is ignored.
• FILENAME is a file path or name relative to default-directory.

💡 TIP: If you have a string, or a buffer not associated with a file, use write-region to write a file. Else, if you have a buffer already associated with a file, use save-buffer. [see Emacs Lisp: Buffer Functions]

;; write region to file
(write-region (point-min) (point-max) "~/temp.txt")

;; write string to file
(write-region "something something" nil "~/temp.txt")

write-file

(write-file FILENAME &optional CONFIRM)

Write buffer content into a new file, like “save as”, and open that file.

💡 TIP: do not use this, unless you want the user to see opened file after the command, with syntax coloring and running all hooks of a major mode (which are super slow.). To simply write buffer to file, use write-region.

(write-file "~/new.txt")

append-to-file

(append-to-file START END FILENAME)

Append text between 2 positions in current buffer to a file.

• START and END are buffer positions.
• If START is nil, write whole buffer. END is ignored.
• If START is a string, write that. END is ignored.
• FILENAME is a file path or name relative to default-directory.

;; append whole buffer content to a file
(append-to-file (point-min) (point-max) "~/test.txt" )

save-buffer

(save-buffer &optional ARG)

A user-oriented command to save current buffer. If buffer is not associated with a file, it prompts for a path.

💡 TIP: avoid using this, because it also invokes automatic backup and other hooks.

Create New File

with-temp-file

(with-temp-file FILE BODY)

Create a new buffer, make it current, evaluate BODY, and write the buffer to FILE.

Existing file at FILE is overwritten.

The value returned is the value of the last form in BODY.

;; create a file with text hello

(with-temp-file "test.txt"
  (insert "hello"))

Reference

• Files (ELISP Manual)