Apache subversion (SVN ) is an open source revision control system distributed under free license.

It is used to maintain current and historical versions of file. It is successor of widely used concurrent version system. It is founded by Collabnet company .It is same as CVS with some new features than CVS and fixed some bugs of CVS. Apache Subversion is abbreviated as (SVN) .

It is founded by Collabnet in 2000 to develop an open source version control system. In November 2009 ,Subversion accepted by Apache Incubator,and this was the beginning of process to became a top-level Apache project.
Now a day’s subversion is very much popular among the developers. More than one person can work on same file by using subversion. The big benefit of using subversion is the ability to merge changes on the working file so that more than one developer can work on the same file. With Subversion each developer has its own working copy of repository. We do changes on our working copy and commits on the repository .When more than one person working on same file and using SVN then by using the update the changes done by one person can be merges on our working copy so that no conflicts arise. Conflicts are arise only when two developer made changes on same line. These can be solved manually but there is very rare chances for conflicts .So with subversion on the same project more than one developer across different countries can work .

SOME USEFUL SVN COMMANADS

1: Checkout command

synatx: svn checkout url
svn co url

Example: svn co http://svn.letsknowit
(This can create a copy of theranjeet.com in your default folder
To Copy it in a folder we can write our folder name to copy in a folder)
svn co http://svn.letsknowit test
(This can copy theranjeet.com in test folder)

2: Update command

synatx: svn update filename
svn up 
(To take the update in a folder in the site we have first go in that folder from cd command)
cd letsknowit
foldername#/ cd subfolder
foldername/subfolder# svn up
(This can update only subfolder)

Example: svn up
(This can update your current folder)
cd letsknowit
letsknowit # svn up
(This can upadte the files of letsknowit)
cd letsknowit
letsknowit #/ cd admin
letsknowit /admin#/ svn up
(This can update the admin folder)

3: Commit command

synatx: svn commit -m "message" 
svn ci -m "message" 
(This command update the file on our server)
(This command made the changes on server file what changes we have done on our own copy)

Example: svn ci -m "update the query" post.php
cd letsknowit
letsknowit#/ cd admin
letsknowit/admin#/ svn ci -m "upadte the query in post file" post.php

4: Add command

synatx:svn add 
svn commit -m "message" 
(This command add a new file on the repository on the server)
After adding a new file to the repository we have to commit that file on
the server by commit commands.

Example: svn add comment.php
svn commit -m "this file is useful for comment" comment.php

5=>Remove command

synatx:svn remove -m "message" filepath
svn delete -m "message" filepath
svn rm -m "message" filepath
(The remove/delete/rm command used to delete the file from repository)

Example:svn remove -m "deleting this file for a purpose" http://letsknowit.com/admin/error.php

6: Revert command

synatx:svn revert 
(This command overwrite the local file with the repository file)

Example: svn revert post.php