Techie Hints

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SVN Installation on Ubuntu

$ sudo apt-get install subversion


It requires to need a directory for your repositories, as well as other Subversion-related files. Recommended use /home/svn or /usr/local/svn for this purpose, and you can choose either. I prefer /usr/local/svn over /home/svn, as I like to keep /home for home directories of real users of the system.

$ sudo mkdir /usr/local/svn


Inside this directory, create another one to hold your repositories:

$ sudo mkdir /usr/local/svn/repos


Now, you need to set some access permissions on those directories. You only want to allow certain users of your system (that is, yourself and the other developers) to access the repositories, so add a new group for those users. Name the group svn.

$ sudo groupadd svn


Then, change the group ownership of /usr/local/svn/repos to the new group using the chgrp command:

$ sudo chgrp svn /usr/local/svn/repos


The members of the svn group also need write access to the repos directory, so use chmod to add the write permission for the group:

$ sudo chmod g+w /usr/local/svn/repos


Additionally, you need to make sure that all new files and directories created in the repos directory (in other words, anything committed to the repositories) will also be owned by the group. To accomplish this, use chmod again to set the set-group-ID bit on the directory, which causes any file created inside it to have the same group ownership as the directory itself. Effectively, everything in repos will belong to the svn group.

$ sudo chmod g+s /usr/local/svn/repos


OK, so you now have the repositories directory with proper permissions, ready to be used by the svn group. Go ahead and add yourself to the group:

$ sudo usermod -a -G svn michal


However, your new group membership will not be effective for the current session, so you need to log out and log back in. When you’re back, you can verify that your account is recognized as a member of the svn group:

$ groups


michal adm dialout cdrom plugdev lpadmin admin sambashare svn

If the other developers have user accounts on your server, add them to the group too:

$ sudo usermod -a -G svn jimmy $ sudo usermod -a -G svn craig


If they don’t, they will still be able to access the repositories, but only using the basic svn protocol, not the secure svn+ssh method.

Creating a Test Repository

You can now create a repository. In the following steps, I’ll demonstrate how to create a simple test repository containing one text file, and how to check out and commit files. If you’re not familiar with Subversion, then this could be a good exercise to learn the basics. Otherwise, you can skip all the test checkouts and commits and just create the repository for your project.

The repository will be a subdirectory in the repos directory, and will have its group ownership set to svn (thanks to the chmod g+s you did earlier). However, that’s not all – you also need to make sure the repository will be group writable, so that the other members of the svn group will be able to commit files. To do this, set the umask to 002:

$ umask 002

This command sets the new file mode creation mask which controls the default permissions of any new file that you create. The default value is 022 and it corresponds to read/write permissions for the file owner, and read permissions for the group and others. The new value, 002, also gives write permissions to the group, which is just what you need.

Create the repository using the svnadmin command:

$ svnadmin create /usr/local/svn/repos/test

And set back the default umask:

$ umask 022

So you now have an empty repository, waiting for you to commit something to it. But, before you do this, you need to check out the current version (i.e., the empty directory) to create a working copy.

$ svn checkout file:///usr/local/svn/repos/test Checked out revision 0.

The working copy has been checked out to a new directory named test. Go ahead and create a simple “hello world” text file in that directory:

$ cd test $ echo ‘Read Me!’ > readme.txt

Then, add it to version control with the svn add command:

$ svn add readme.txt A         readme.txt

Finally, commit it using svn commit:

$ svn commit -m “Added a ‘hello world’ text file.” Adding         hello.txt Transmitting file data . Committed revision 1.

The hello.txt file is now in the repository.

Accessing the Repository with the Svn Protocol

Remote repository access with the svn protocol requires you to use svnserve, a Subversion server program. Each repository has a svnserve configuration file (stored in the conf subdirectory) which controls how the repository can be accessed with svnserve.

First, create a passwords file that lists the users of the repository and their passwords. This will be a common passwords file for your development team and you will be able to use it with multiple repositories.

$ sudo gedit /usr/local/svn/passwd-team

Here’s a sample passwords file. Each line (except the first one, which is the configuration section name) defines a user name and the corresponding password.

[users]

sandeep = somepassword

techiehints = anotherpassword

Since the passwords are stored unencrypted, it’s important that you protect the passwords file by setting the proper permissions. The file should not be readable by anyone except the owner (which is root), so change its mode to 600:

$ sudo chmod 600 /usr/local/svn/passwd-team

Then, open the svnserve configuration file in the test repository:

$ gedit /usr/local/svn/repos/test/conf/svnserve.conf

There’s probably some default configuration in the file, but you can just remove everything and enter this:

[general] anon-access = none password-db = /usr/local/svn/passwd-team realm = Team

The anon-access = none line denies access to the repository to unauthenticated users (by default, they are allowed read access, so they can do checkouts). The password-db setting tells svnserve where to look for the passwords file when authenticating users, and the realm setting defines the name of the authentication realm.

OK, the configuration is ready, so you can now launch svnserve.

$ sudo svnserve -d –foreground -r /usr/local/svn/repos

The command-line options tell svnserve to run in daemon mode (-d) as a foreground process (--foreground), and to look for repositories in the repos dir that was created earlier (-r /usr/local/svn/repos). Normally the program should be running in the background (that’s what daemon processes do), but at this moment you only need to test it, so it’s more convenient to run it in the foreground, where you can easily kill it with Ctrl+C.

Now, try accessing the repository using the svn protocol. You can try it on another machine over the network, or on the same computer (in another terminal). In the latter case, make sure you’re not doing the checkout in the same directory where the previous test working copy was checked out, because it won’t work – either delete the test directory, or cd to some other location.

Enter the following svn checkout command, replacing xxx.xxx.xx.xx with the IP address of your Subversion server (if you’re testing on the same machine, you can use 127.0.0.1):

$ svn checkout svn://xxx.xxx.xx.xx:3690/test –username sandeep

The server will ask you for password:

Authentication realm: <svn://xxx.xxx.xx.xx:3690> Team Password for ‘sandeep’:

Then, it proceeds with the checkout.

A    test/hello.txt Checked out revision 1.

And there’s your working copy. Now, check if it works the other way – try modifying the file and committing it back to the repository. Open hello.txt with a text editor and add some text:

$ cd test

$ gedit hello.txt


How to create new repository & assign users follow simple steps:


svnadmin create /usr/local/svn/repos/my-web
umask 022
sudo vi /usr/local/svn/web-team

Add Content:

[users]
name = password

sudo chmod 600 /usr/local/svn/web-team

sudo vi /usr/local/svn/repos/my-web/conf/svnserve.conf

[general]
anon-access = none
password-db = /usr/local/svn/web-team
realm = Team

sudo fuser -k 3690/tcp # kills the previous running instance on 3690
sudo svnserve -d –foreground -r /usr/local/svn/repos &

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