persistent-scratch is an Emacs package that preserves the state of scratch buffers accross Emacs sessions by saving the state to and restoring it from a file.

The package is available in MELPA and MELPA Stable.

If you have MELPA or MELPA Stable in package-archives, use

M-x package-install RET persistent-scratch RET

If you don't, open persistent-scratch.el in Emacs and call package-install-from-buffer.

Other installation methods are unsupported.

To save the current state of scratch buffers to file indicated by persistent-scratch-save-file:

M-x persistent-scratch-save

To restore scratch buffers from persistent-scratch-save-file:

M-x persistent-scratch-restore

To save the state to an arbitrary file:

M-x persistent-scratch-save-to-file

To restore the state from an arbitrary file:

M-x persistent-scratch-restore-from-file

To toggle periodic autosave:

M-x persistent-scratch-autosave-mode

To create a new backup file (only when backup is enabled, see persistent-scratch-backup-directory), so that the next persistent-scratch-save won't overwrite the existing backup:

M-x persistent-scratch-new-backup

To customize the save file path, what state to save, the autosave period, what buffers are considered scratch buffers and whether to backup old saved states:

M-x customize-group RET persistent-scratch RET

Variables can be customized either via customize or by setting them via setq directly.

To both enable autosave and restore the last saved state, if any, on Emacs start, add

(persistent-scratch-setup-default)

to the init file. This will not error when the save file doesn't exist.

To just enable autosave, enable persistent-scratch-autosave-mode like any other minor mode:

(persistent-scratch-autosave-mode 1)

To just restore the last saved file, use persistent-scratch-restore. Bear in mind it may signal an error if there's no save file, so it's a good idea to call it inside ignore-errors or with-demoted-errors.