14.6.6 Examining And Comparing Old Versions

C-x v ~ version RET

Examine version version of the visited file, in a buffer of its own (vc-version-other-window).

C-x v =

Compare the current buffer contents with the latest checked-in version of the file.

C-u C-x v = file RET oldvers RET newvers RET

Compare the specified two versions of file.

You can examine any version of a file by first visiting it, and then using C-x v ~ version RET (vc-version-other-window). This puts the text of version version in a file named filename.~version~, then visits it in a separate window.

To compare two versions of a file, use the command C-x v = (vc-diff).

Plain C-x v = compares the current buffer contents (saving them in the file if necessary) with the last checked-in version of the file. With a prefix argument, C-x v = reads a file name and two version numbers, then compares those versions of the specified file.

If you supply a directory name instead of the name of a work file, this command compares the two specified versions of all registered files in that directory and its subdirectories. You can also specify a snapshot name (see Snapshots) instead of one or both version numbers.

You can specify a checked-in version by its number; you can specify the most recent checked-in version with an empty version number.

This command works by running the vcdiff utility, getting the options from the variable diff-switches. It displays the output in a special buffer in another window. Unlike the M-x diff command, C-x v = does not try to find the changes in the old and new versions. This is because one or both versions normally do not exist as files. They exist only in the records of the master file. See Comparing Files, for more information about M-x diff.