# CVS to SVN Crossover Guide

## Purpose

This document provides an alternate method of learning Subversion. Many users dislike learning new technology via a theoretical "top down" approach, as provided by the Subversion Book. Instead, this document presents Subversion from the "bottom up": it shows a CVS command or task, and then shows the equivalent task in Subversion (along with relevant book links.) It's essentially a re-indexing of topics covered by the book, keyed on CVS tasks.

## Table of Contents

### Setup

- Repository creation
- Importing data
- Installing a server
- Authenticating to a server
- Browsing a repository
- Checking out a working copy

### Basic Work Cycle

- Seeing locally changed items
- Seeing out-of-date items
- Scheduling additions or deletions
- Copying and moving
- Undoing local changes
- Updating and committing
- Resolving conflicts
- Adding a binary file
- Using native line-endings

### Examining history

- Seeing history of an item
- Comparing two versions of an item

### Branching/Tagging/Merging

- Creating a branch
- Moving a working copy to a branch
- Finding the beginning of a branch
- Porting a single change
- Merging a whole branch
- Reverting a committed change
- Resurrecting deleted items
- Creating a tag
- Tweaking a tag
- Seeing all tags
- Comparing two tags
- Seeing logs between two tags

### Other tasks

- Using modules
- Line endings and keywords

## Repository creation

Create a new repository for holding versioned data.

CVS | Subversion
--- | ---

Commands:
  `$ cvs -d /usr/local/repos init`
Explanation:
  Creates a new directory `repos` ready to hold RCS files and config scripts.

Commands:
  `$ svnadmin create /usr/local/repos`
Explanation:
  Creates a new directory `repos` containing BerkeleyDB files and config scripts.

Book References:
  Repository Creation and Configuration

## Importing data

Populate a new repository with initial data. Assuming that you have a tree of code in the local directory `myproj/`, and you want to move this tree into the repository.

CVS | Subversion
--- | ---

Commands:
  `$ cd myproj`
  `$ cvs -d /usr/local/repos import myproj/ none start`
Explanation:
  This copies the contents of the current working directory to a new directory (`myproj`) in the CVS repository. The CVS repository now contains a directory `/myproj/` at the top level.

Commands:
  `$ svn mkdir file:///usr/local/repos/tags`
  `$ svn mkdir file:///usr/local/repos/branches`
  `$ svn import myproj/ file:///usr/local/repos/trunk`
Explanation:
  Though not strictly required, we deliberately create `/tags` and `/branches` top-level directories in the repository, to hold tags and branches later on. Then we import the contents of the local `myproj/` directory into a newly created `/trunk` directory in the repository.

Book References:
  Choosing a repository layout
  svn import

## Installing a server

Make the repository available to clients via a network.

CVS | Subversion
--- | ---

Commands:
  (too complex to demonstrate here)
Explanation:
  Export the repository via the cvs pserver program. It can be launched by either inetd or a client's ssh remote request.

Commands:
  (too complex to demonstrate here)
Explanation:
  Export the repository with the Apache 2.0.x server, or via the svnserve program. The latter can run as a standalone daemon, can be launched by inetd, or invoked by a client's ssh remote request.

Book References:
  Server configuration

## Authenticating to a server

Have a network client prove its identity to a version control server.

CVS | Subversion
--- | ---

Commands:
  `$ cvs -d :pserver:user@host:/repos command…`
Explanation:
  When contacting a repository, the client pre-emptively "pushes" its authentication credentials at the server.

Commands:
  `$ svn command URL…`
  `Password for 'user': XXXXXXX`
Explanation:
  The client's authentication credentials are "pulled" from the user interactively, and only when the server deems that a challenge needs to be made. (And contrary to popular belief, the `--username` and `--password` options are merely values to be used if the server issues a challenge; they do not "push" the credentials at the server.)

Book References:
  Network Model

## Browsing a repository

Browse the repository as a filesystem, perusing file contents and history as well (older versions of files or trees.)

CVS | Subversion
--- | ---

Commands:
  (not possible with commandline client)
Explanation:
  Not possible with commandline client. A third-party web server tool such as ViewCVS must be used.

Commands:
  `$ svn list URL [-r rev] [-v]`
  `$ svn cat URL [-r rev]`
Explanation:
  The `svn list` and `svn cat` commands allow interactive browsing of a repository (and all previous states of a repository) from the commandline. (The `--verbose [-v]` switch displays full listing information.) If Apache is being used as a Subversion server process (i.e. clients access via http://), then the latest version of the repository can be directly browsed by entering URL into any web browser. Additionally, a third-party web server tool (such as ViewCVS) can be used with Subversion.

Book References:
  svn list

## Checking out a working copy

Create a workspace on local disk which mirrors a directory in the repository.

CVS | Subversion
--- | ---

Commands:
  `$ cvs -d /usr/local/repos checkout myproj`
  `U myproj/foo.c`
  `U myproj/bar.c`
  `…`
Explanation:
  Creates a local directory `myproj` which is a mirror of the repository directory `/myproj`.

Commands:
  `$ svn checkout file:///usr/local/repos/trunk myproj`
  `A myproj/foo.c`
  `A myproj/bar.c`
  `…`
Explanation:
  Assuming that the original project data was imported into the repository `/trunk` directory, this creates a local directory `myproj` which is a mirror of the repository directory `/trunk`. Standard Subversion convention is to do "mainline" development in `/trunk`. See branching and tagging sections for more details.

Book References:
  Initial Checkout
  svn checkout

## Seeing locally changed items

Discover which items in the working copy have local modifications or are scheduled for addition/deletion.

CVS | Subversion
--- | ---

Commands:
  `$ cvs status`
  `…`
  `File: baz.c Status: Up-to-date`
  `…`
  `$ cvs update`
  `M foo.c`
  `U bar.c`
  `…`
Explanation:
  The `cvs status` command shows whether a file is locally modified or out of date, including information about working revision and branch info. Unfortunately, because the output is so verbose and hard to read, many users run `cvs update` instead, which shows a more compact listing of modified files (and of course, it also causes the server to merge changes into your working copy.)

Commands:
  `$ svn status`
  `M foo.c`
  `…`
Explanation:
  Shows modified files only. Very fast, as it does not use the network. Does not update your working copy, yet still shows a single-line display, much like `svn update`. To see working revision and branch information, run `svn info`.

Book References:
  Examine Your Changes
  svn status

## Seeing out-of-date items

Discover which items in the working copy are out-of-date (i.e. newer versions exist in the repository.)

CVS | Subversion
--- | ---

Commands:
  `$ cvs status`
  `…`
  `File: baz.c Status: Needs Patch`
  `…`
  `$ cvs -n update`
  `M foo.c`
  `U bar.c`
  `…`
Explanation:
  The `cvs status` command shows whether a file is locally modified or out of date, including information about working revision and branch info. A less verbose option is to run `cvs -n update` instead, which shows a compact listing of both out-of-date and locally modified files, without actually updating the working copy.

Commands:
  `$ svn status -u`
  `M 46 foo.c`
  `M * 46 bar.c`
  `* 46 baz.c`
  `…`
Explanation:
  Shows modified files (`M`) as well as out-of-date files (`*`). Contacts repository, but doesn't modify the working copy. To see working revision and branch information, run `svn info`.

Book References:
  Examine Your Changes
  svn status

## Scheduling additions or deletions

Schedule a working-copy file or directory to be added or removed from the repository.

CVS | Subversion
--- | ---

Commands:
  `$ touch foo.c`
  `$ cvs add foo.c`
  `cvs server: scheduling file `blah' for addition`
  `cvs server: use 'cvs commit' to add this file permanently`
  ``
  `$ mkdir new-dir`
  `$ cvs add new-dir`
  `Directory new-dir added to the repository`
  ``
  `$ rm bar.c`
  `$ cvs rm bar.c`
  `cvs remove: scheduling `bar.c' for removal`
  `cvs remove: use 'cvs commit' to remove this file permanently`
  ``
  `$ rm -rf old-dir/*`
  `$ cvs rm old-dir`
  `cvs remove: Removing 3bits`
  `…`
Explanation:
  Schedules a file or directory for addition or removal to/from the repository. The repository will not be changed until the user runs `cvs commit`, except for the case of adding a directory, which immediately changes the repository. Also, directories cannot be truly removed from the repository, just emptied out. (`cvs update -P` will prune empty directories from your working copy.)

Commands:
  `$ touch foo.c`
  `$ svn add foo.c`
  `A foo.c`
  ``
  `$ mkdir new-dir`
  `$ svn add new-dir`
  `A new-dir`
  ``
  `$ svn rm bar.c`
  `D bar.c`
  ``
  `$ svn rm old-dir`
  `D old-dir/file1`
  `D old-dir/file2`
  `…`
Explanation:
  Schedules a file or directory for addition or removal to/from the repository. The repository will not be changed until the user runs `svn commit`. The scheduled operations are shown as `A` or `D` by `svn status`, and `svn revert` can un-do the scheduling. Directories really can be deleted (though as with all deleted items, continues to exist in history.)

Book References:
  Make Changes to Your Working Copy
  svn add
  svn delete

## Copying and moving

Copy or move/rename a file or directory.

CVS | Subversion
--- | ---

Commands:
  (not possible.)
Explanation:
  Not possible, unless an administrator directly mucks with RCS files in the repository. (And in that case, no history records the act of copying or renaming.)

Commands:
  `$ svn copy foo.c foo2.c`
  `A foo2.c`
  ``
  `$ svn copy dir dir2`
  `A dir2`
  ``
  `$ svn move bar.c baz.c`
  `A baz.c`
  `D bar.c`
  ``
  `$ svn move dirA dirB`
  `A dirB`
  `D dirA/file1`
  `D dirA/file2`
  `…`
Explanation:
  The `svn copy` command schedules a file or directory for addition to the repository, recording the "source" of the copy. After committing, `svn log` on the copied item will trace history back through the original copy-source. The `svn move` command is exactly equivalent to running `svn copy`, followed by an `svn delete` on the copy-source: the result is a new item scheduled for addition (with copy-history attached) and the original item scheduled for deletion.

Book References:
  Make Changes to Your Working Copy
  svn copy
  svn move

## Finding the beginning of a branch

If you're attempting to merge an entire branch into another, you need to compare the "root" and "tip" of the source branch, and then merge those differences into a working copy of the target branch. Obviously the "tip" of the branch can be represented by using the `HEAD` keyword. But how do you find the "birth" revision of the source branch?

The easiest solution is to run

       $ svn log -v --stop-on-copy source-branch-URL
       …

This command will display every change ever made to the branch, but `--stop-on-copy` option will cause the output to stop as soon as detects a copy operation in the branch's history. By definition, then, the very last log entry printed will show the copy being made. It will look something like:

    r9189 | joe | 2004-03-22 10:10:47 -0600 (Mon, 22 Mar 2004) | 1 line
    Changed paths:
       A /branches/mybranch (from /trunk:9188)

In this case, you would then know to compare revisions 9189 and HEAD of the branch in order to perform the merge:

       $ svn merge -r9189:HEAD source-branch-URL target-branch-WC
       …

## Seeing all of a project's tags

Assuming you've been following a consistent policy for creating tag-copies, then this is just a matter of running `svn ls` on a directory containing your tags. Typically you would run it on the `/tags` directory in your repository, although you're certainly free to organize this directory in a more complex way, or invent a different convention altogether.

As an example, you can see all of Subversion's tags by running:

       $ svn ls --verbose http://svn.collab.net/repos/svn/tags
         …
           7739 kfogel              Nov 13 22:05 0.33.0/
           7796 josander            Nov 18 12:15 0.33.1/
           7932 josander            Dec 03 17:54 0.34.0/
           8045 josander            Dec 19 15:13 0.35.0/
           8063 josander            Dec 20 11:20 0.35.1/
           8282 josander            Jan 13 14:15 0.36.0/
           8512 josander            Jan 24 17:31 0.37.0/
           8810 kfogel              Feb 23 03:44 1.0.0/
         …

## Seeing the differences between two tags

Just use `svn diff` in its fully expanded form, which compares any two URLs:

       $ svn diff tagURL1 tagURL2
       …

## Seeing logs between two tags

This is a somewhat common practice in CVS, and is doable in Subversion, but requires a little bit more work. Assuming that you've made two tags of `/trunk` at different points in time, the ultimate goal here is to run

       $ svn log -rX:Y trunkURL

…where X and Y are the revisions from which the two tags were copied. To discover X and Y, you can use the same technique described in the previous section ("finding the beginning of a branch".) Just use the `--stop-on-copy` option when logging the history of each tag. No commits happen on tag directories, so the following commands should each produce exactly one log entry:

       $ svn log -v --stop-on-copy tag1-URL

       r3520 | joe | 2004-03-12 15:28:43 -0600 (Fri, 12 Mar 2004) | 1 line
       …

       $ svn log -v --stop-on-copy tag2-URL
       a
       r4177 | joe | 2004-03-12 15:28:43 -0600 (Fri, 12 Mar 2004) | 1 line
       …

So in this example, the values of X and Y are 3520 and 4177. Now you can view all `/trunk` changes between those two points in time:

       $ svn log -r3520:4177 trunkURL
       …

## Fixing an incorrect tag

If your tag is a bit off, you can "adjust" it just as people often do in CVS. Simply check out a working copy of the tag directory, make any changes you wish, and commit.

Remember, because branches and tags are directories, they can also be deleted when they're no longer of any use to your project. They'll continue to exist in the repository's history.

## Creating/using "modules"

Compare CVS Modules vs. svn:externals.