Here are two Dired commands that compare specified files using
diff. They show the output in a buffer using Diff mode
(see Comparing Files).
dired-diff). The file at the mark is the first argument of
diff, and the file at point is the second argument. This refers to the ordinary Emacs mark, not Dired marks; use C-<SPC> (
set-mark-command) to set the mark at the first file's line (see Setting Mark).
dired-backup-diff). If the current file is itself a backup, compare it with the file it is a backup of; this way, you can compare a file with any one of its backups.
The backup file is the first file given to