Emacs Advent Calendar 23: Version Control

Wed 2015-12-23

With VC mode Emacs provides a unified interface to many common version control systems; both centralized (e.g. subversion) and decentralized (e.g. git).

As such, it can not accomodate for all use cases, meaning that some operations still have to be performed on the command line (e.g. pushing a git repository).

When you visit a file under version control, emacs will notice that and activate VC minor mode. The modeline will show an indicator with the current revision number and other information specific to the VCS used in the background (e.g. the git branch). It will also indicate if the file has uncommited changes.

To make use of the basic VC mode functionality you will just have to learn one single keybinding: C-x v v will always do the "next sensible thing". When a file is not registered with the VCS it will be registered. The next invocation will commit it, opening a buffer for entry of the commit log message. Pressing C-c C-c will commit the changes.

To operate on multiple files, press C-x v d to open a *vc-dir* buffer. This looks similar to dired. You can mark files with m and unmark them with u. When multiple files are marked they form a VC fileset and VC commands will operate on them as a group. For keybindings in this buffer have a look at the manual.

To compare a file with its base version, press C-x v =. To look at another revision of the current file use C-x v ~ which will ask for the revision number and visit it in another window. Running C-x v g will show an annotated view of the current file, telling when each line was changed last.

Log can be displayed either for the current VC fileset (C-x v l) or the whole repository (C-x v L). It is shown in a buffer named *vc-change-log*. If it is in a compact form, pressing <RTE> on an entry will reveal details of the commit. Other useful keybinding in this buffer are f (visit revision), a (annotate) and d (show diff to next earlier file).

If you decide to undo your current work and want to revert a file to its base version, run C-x v u.

For full documentation on VC mode have a look at chapter 28.1 (Version Control) of the Emacs Reference Manual.

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This text by Ludger Sandig is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.