Submitting changes to a central repository using Subversion is not difficult. But there are some steps to be respected at risk of committing mistakes literally. The safe route is as follows.
1. Go to the repository
$ cd featured-image-from-url
2. Update the repository
$ svn up
Updating ‘.’:
At revision 1295298.
3. Modify the file
$ vim trunk/includes/thumbnail.php
4. Check the status
$ svn status
M trunk/includes/thumbnail.php
5. Check the differences
$ svn diff
Index: trunk/includes/thumbnail.php
===================================================================
— trunk/includes/thumbnail.php (revision 1295298)
+++ trunk/includes/thumbnail.php (working copy)
– return $html;
+ echo $html;
6. Commit the changes
$ svn ci -m “return was replaced by echo to facilitate the plugin use in nonstandard themes”
Sending trunk/includes/thumbnail.php
Transmitting file data .
Committed revision 1295309.
Was it very easy, right? With only some Subversion command lines you had your changes in the central repository!