CVS to SVN^book Crossover Guide

Key Differences between CVS and Subversion

• Versions are global. Whereas in CVS, each file had an individual version number, in Subversion, the entire repository has a single version number. The version number is a simple integer, and is incremented with every svn commit operation.
• Subversion has atomic changesets. This is a corollary to the fact that version numbers are global. All of the changes made in a single commit operation are treated as a single revision to the repository.
• Subversion manages directories as well as files.
• Subversion understands renaming of files and directories.

Structure

This is the location of the M3DP project repository on pppl svn server. m3dp/ This is the subproject. trunk, branches tags

https://svnsrv.pppl.gov/svn/repos/

This is the location of the M3D project repository on pppl server.

m3dp/

This is the subproject.

trunk

main branch of development.

branches

tags

NEW FEATURES: Browsing a repository ^{linear mhd component svn repository at svnsrv.pppl.gov}

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 http://svnsrv.pppl.gov/svn/repos [-r rev] [-v] $ svn cat http://svnsrv.pppl.gov/svn/repos [-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.

NEW FEATURE: Undoing Working Changes

CVS	Subversion
Commands: impossible	Commands: svn revert file Explanation: reverts the file to its pre-modified state; can undo any scheduled operations: e.x., you might decide that you don't want to add a new file after all; or perhaps you mistakenly removed a file from version control.

NEW FEATURES: 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.

Common FEATURES: 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 M3D files and config scripts.	Commands: $ svnadmin create http://svnsrv.pppl.gov/svn/repos Explanation: Creates a new directory repos containing M3D files and config scripts.

Common FEATURES: 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 http://svnsrv.pppl.gov/svn/repos… 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.)

Common FEATURES: 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 http://svnsrv.pppl.gov/svn/repos/tags $ svn mkdir http://srnsrv.pppl.gov/svn/repos/branches $ svn import myproj/ http://svnsrv.pppl.gov/svn/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. Another Way: mkdir tmpdir cd tmpdir mkdir projectA mkdir projectA/trunk mkdir projectA/branches mkdir projectA/tags mkdir projectB mkdir projectB/trunk mkdir projectB/branches mkdir projectB/tags svn import . http://svnsrv.pppl.gov/svn/repos --message 'Initial repository layout'   Adding projectA   Adding projectA/trunk   Adding projectA/branches   Adding projectA/tags   Adding projectB   Adding projectB/trunk   Adding projectB/branches   Adding projectB/tags   Committed revision 1. cd .. rm -rf tmpdir svn list --verbose http://svnsrv.pppl.gov/svn/repos

Common FEATURES: 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 http://svnsrv.pppl.gov/svn/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.

Common FEATURES: Seeing locally changed and out-of-date items

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

CVS	Subversion
Commands: $ cvs update -n Explanation: The cvs udpate -n command shows whether a file is locally modified or out of date, including information about working revision and branch info without actually updating the working copy.	Commands: $ svn status 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.

Common FEATURES: update working copy

CVS	Subversion
Commands: $ cvs update	Commands: $ svn update Explanation: svn remembers that a file is in a state of conflict, and won't allow you to commit your changes until you run svn resolved.

Common FEATURES: Examine the details of your local modifications

CVS

Subversion

Commands: cvs diff Explanation: Shows you the details of your changes

Commands: svn diff Explanation: Shows you the details of your changes. Files scheduled for addition are displayed as all added-text, and files scheduled for deletion are displayed as all deleted text. Output is displayed in unified diff format. That is, removed lines are prefaced with - and added lines are prefaced with +. "svn diff > patchfile" prints filename and offset information useful to the patch program.

Common FEATURES: Resolve conflicts

CVS	Subversion
Commands:	Commands:

Common FEATURES: 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.)

Common FEATURES: Commit Your Changes

CVS	Subversion
Commands: svn commit -m "Corrected number of cheese slices."	Commands: svn commit -m "Corrected number of cheese slices." -F logmsg Explanation: If somebody has changed any of the same files that you did when you weren't looking, the entire commit will fail with a message informing you that one or more of your files is out-of-date: