These facilities provide information about which version of Emacs is in use.
This function returns a string describing the version of Emacs that is running. It is useful to include this string in bug reports.
(emacs-version)
⇒ "GNU Emacs 26.1 (build 1, x86_64-unknown-linux-gnu,
GTK+ Version 3.16) of 2017-06-01"
If here is non-nil, it inserts the text in the buffer
before point, and returns nil. When this function is called
interactively, it prints the same information in the echo area, but
giving a prefix argument makes here non-nil.
The value of this variable indicates the time at which Emacs was
built. It uses the style of
current-time (see Time of Day), or is nil
if the information is not available.
emacs-build-time
⇒ (25194 55894 8547 617000)
(This timestamp is (1651169878008547617 . 1000000000)
if current-time-list was nil when Emacs was built.)
The value of this variable is the version of Emacs being run. It is a
string such as "26.1". A value with three numeric components,
such as "26.0.91", indicates an unreleased test version.
(Prior to Emacs 26.1, the string includes an extra final component
with the integer that is now stored in emacs-build-number;
e.g., "25.1.1".)
The major version number of Emacs, as an integer. For Emacs version 23.1, the value is 23.
The minor version number of Emacs, as an integer. For Emacs version 23.1, the value is 1.
An integer that increments each time Emacs is built in the same directory (without cleaning). This is only of relevance when developing Emacs.
A string that gives the repository revision from which Emacs was
built. If Emacs was built outside revision control, the value is
nil.
A string that gives the repository branch from which Emacs was built.
In the most cases this is "master". If Emacs was built outside
revision control, the value is nil.