Version Control

A Short Example

mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git init
Initialized empty Git repository in /home/mbone/Developer/vc_test/repo1/.git/
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ emacs -nw foo
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git status
On branch master

Initial commit

Untracked files:
  (use "git add <file>..." to include in what will be committed)

        foo

nothing added to commit but untracked files present (use "git add" to track)
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git add foo
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git commit -m "adding the foo file"
[master (root-commit) 2d08ac5] adding the foo file
 1 file changed, 1 insertion(+)
 create mode 100644 foo
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git status
On branch master
nothing to commit, working directory clean
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$ git log
commit 2d08ac51f450de81b66e54456b061d28b6f225ae
Author: Matt Bone <thatmattbone@gmail.com>
Date:   Wed Jan 27 18:25:10 2016 -0600

    adding the foo file
mbone@mbone-UX303LB:~/Developer/vc_test/repo1$

Version Control History

ESR offers a very interesting summary of version control (if slightly unfinshed) that was useful in putting this lecture together. It is worth a read.

Versioned File Systems

While quite different from source control systems, versioned files have been around for some time. There are similarities. One example is the system found in vms and another is that found in MVS and later os/390 and z/os.

RCS (gen 1)

RCS seems to be the grandfather of all our existing version control systems. It is described in this academic paper, RCS-A System for Version Control. RCS has no concept of networking, though it could have been used in a shared filesystem setting. It also has no concept of a ‘project’ or changes made to a group of files. Instead, each file is versioned individually.

CVS and SVN (gen 2)

CVS began its life as a wrapper around RCS files. It allowed for the repo notion we’ve come to know and love. Eventually it supported a client/server model and allowed users to work offline (but not make commits offline).

[Subversion or SVN]() supplanted CVS quite thoroughly.

Bitkeeper, the Linux Kernel, and DVCSs (gen 3)x

Moder version control systems such as git and mercurial evolved out of an open source controversy. Monotone also provided inspiration.

The really interesting thing about these gen3 systems is the ability to make commits offline and shuffle change sets between repos without a string client/server model. Some have theorized that this allows for better development. Other advantages in these more modern systems is the improvement and wider adoption of merges. Though this pain has been alleviated somewhat in newer versions of SVN.

Other Crazy Stuff

The world of version control is not stagnent. For example darcs and its theory of patches offers some alternative thoughts on version control.

Fossil contains an entire suite of collaboration tools inside the version control system.

Collaboration Tools

Sourceforge, Github, et. al.

Sourceforge and then google code, github, bitbucket and others offer us a model of collaboration we’re probably all familiar with. These online tools provide things like issue tracking, wikis, visual diff viewers, mailing lists, etc.

Linux Kernel Mailing List

Development of the linux kernel does things a bit differently…

Security/Workflow Concerns