SVN Branch/Merge tutorial
NOTE: THE EXAMPLES ARE DONE ON ALFS PC, AND ANY DIRECTORY NAMES CONTAINING “alfg” ARE NOT VALID ON YOUR PC!! USE SOME NAMES WHICH MAKE SENSE ON YOUR PC!
PART 1 : Create a repository and put a file there
CREATE A REPOSITORY
alfg@pc4400:~$svnadmin create $HOME/svnrepos
CREATE A WORKING DIRECTORY WITH CODE
alfg@pc4400:~$mkdir $HOME/testproject
Use the following as the file test.F90:
program test
implicit none
real, parameter :: a=4.0
real, parameter :: b=5.0
print*, "a is " , a
print*, "b is " , b
print*, "a+b is " , a+b
end program test
CD TO WORKING DIRECTORY AND VERIFY THAT THE TEST FILE IS THERE
alfg@pc4400:~/testproject$ ls -l total 4 -rw-rw-r-- 1 alfg alfg 166 Dec 6 14:51 test.F90
CD TO THE FRESHLY CREATED REPOSITORY AND CREATE “testproject”
alfg@pc4400:~/svnrepos$ svnadmin create testproject
IMPORT YOUR WORKING-DIRECTORY TO THE REPOSITORY
alfg@pc4400:~$svn import $HOME/testproject/ file://$HOME/svnrepos/testproject/trunk -m "Initial version of testproject"
MAKE A BRANCHES-DIRECTORY
alfg@pc4400:~$svn mkdir file://$HOME/svnrepos/testproject/branches/ -m "created branches directory"
=⇒YOU NOW HAVE A REPOSITORY CONTAINING TRUNK AND (EMPTY) BRANCHES DIRECTORY. YOU CAN START TO USE IT
PART 2: Create a working directory for two developers
alfg@pc4400:~$mkdir twoDevelopers alfg@pc4400:~$cd twoDevelopers
CHECK OUT TRUNK FOR ONE DEVELOPER
alfg@pc4400:~/twoDevelopers$svn checkout file://$HOME/svnrepos/testproject/trunk trunk alfg@pc4400:~/twoDevelopers$cd trunk
CREATE A BRANCH BASED ON TRUNK
alfg@pc4400:~/twoDevelopers/trunk$ svn copy file://$HOME/svnrepos/testproject/trunk file://$HOME/svnrepos/testproject/branches/aBranch -m "created branch aBranch"
CD BACK ONE STEP AND CHECK OUT THE BRANCH FOR THE OTHER DEVELOPER
alfg@pc4400:~/twoDevelopers$ svn checkout file://$HOME/svnrepos/testproject/branches/aBranch aBranch
=⇒ THE DIRECTORY “TWODEVELOPERS” NOW HAS TWO DIRECTORIES, ONE WITH TRUNK AND ONE WITH A BRANCH VERIFY THAT THEY ARE THERE USING THE “LS” COMMAND
alfg@pc4400:~/twoDevelopers$ ls -trl total 8 drwxrwxr-x 3 alfg alfg 4096 Dec 9 08:36 trunk drwxrwxr-x 3 alfg alfg 4096 Dec 9 09:40 aBranch
PART 3: Create conflict in the file test.F90
EDIT FILE ON TRUNK
alfg@pc4400:~/twoDevelopers/trunk$ vim test.F90 alfg@pc4400:~/twoDevelopers/trunk$ svn commit -m "added hello" alfg@pc4400:~/twoDevelopers/trunk$ svn update
EDIT FILE ON BRANCH
alfg@pc4400:~/twoDevelopers/aBranch$ vim test.F90 alfg@pc4400:~/twoDevelopers/aBranch$ svn commit -m "added Hi man" alfg@pc4400:~/twoDevelopers/aBranch$ svn update
=⇒ We have now created a conflict between the branch “aBranch” and “trunk”
alfg@pc4400:~/twoDevelopers$ diff aBranch/test.F90 trunk/test.F90 9c9 < print*, "Hi Man! a+b is " , a+b --- > print*, "Hello a+b is " , a+b
PART 4: Test the merge dialog
TRY TO MERGE TRUNK INTO BRANCH
alfg@pc4400:~/twoDevelopers/aBranch$ svn merge file://$HOME/svnrepos/testproject/trunk
You will get the message that there is a conflict in file test.F90, you will have to resolve the conflict Push the “postpone” option to quit the merge dialog
UNDO THE MERGE WITH
alfg@pc4400:~/twoDevelopers/aBranch$ svn revert -R .
=⇒ You have undone the merge, nothing has happened
alfg@pc4400:~/twoDevelopers/aBranch$ svn diff alfg@pc4400:~/twoDevelopers/aBranch$
PART 5: Set up favourite editor as merge tool
1) Create a file somewhere in your pc, for example I use $HOME/bin/mergetoolscript.sh
For emacs users, the content of the script is:
#!/bin/sh emacs -q --eval "(ediff-merge-files-with-ancestor "\"$2"\" \""$3"\" \""$1"\" nil \""$4"\")"
For vi users, the content of the script is:
#!/bin/sh vim -d "+diffsplit $3" "+vert diffsplit $1" "+vert diffsplit $2" -o $4
2) Open your $HOME/.subversion/config file and replace the line with merge tool (NOTE THAT FULL PATH IS NEEDED. NO BLANK CHARACTERS AT BEGINNGING OF LINE!!)
merge-tool-cmd = /home/alfg/bin/mergetoolscript.sh
MAKE SURE SCRIPT IS EXECUTABLE
chmod +x $HOME/bin/mergetoolscript.sh
=⇒ You should now have working merge tools. This will make merging EASY!!
PART 6: Go back to merge operation and use merge tool
alfg@pc4400:~/twoDevelopers/aBranch$ svn merge file://$HOME/svnrepos/testproject/trunk
type “s” to “show all options” and “l” to “launch external tool”.
=⇒ emacs or vi should be invoked in “merge mode”
The vi script shows (your, ancestor, mine) on top and output below. Move around in the different windows with “ctrl+w+arrow”. When in the upper windows you can use “[c” and “]p”] go move to previous/next diffs.
the emacs script shows (yours, mine) on top and merged version (including common ancestor) below
All editing should happen in the lowest part of the editor window
When done editing, save the file and quit the editor
When back in the merge-dialog, press “r” (resolved)
PART 7: Verify that you are happy with merge
alfg@pc4400:~/twoDevelopers/aBranch$ svn diff
Note how it is difficult to understand the diff =⇒ we need to configure a diff tool!
To configure a nice diff-viewer, you need to replace a line in your $HOME/.subversion/config file like this:
diff-cmd = /home/alfg/bin/diffwrap.sh
The script “diffwrap.sh” has be created somewhere on your PC. The script is only TWO LINES long!! (Make sure it is executable with “chmod +x scriptname”)
The content of this script (only two lines) for emacs users can be:
#!/bin/sh emacs --eval "(ediff-files "\"$6"\" \""$7"\" )"
(In emacs, use | (pipeline) key in the “ediff” dialog to toggle between vertical/horizontal diff view)
The content of this script for vi users can be
#!/bin/sh vimdiff $6 $7
Visually verify the diff again using the diff viewer
alfg@pc4400:~/twoDevelopers/aBranch$ svn diff
When you are happy with the diffs, do
alfg@pc4400:~/twoDevelopers/aBranch$ svn commit -m "Successfully branched trunk to my branch"
=⇒ DONE
PART 8: Merge back to trunk
After the conflict is resolved and committed from branch, go back to trunk
alfg@pc4400:~/twoDevelopers/trunk$ svn update alfg@pc4400:~/twoDevelopers/trunk$ svn merge --reintegrate file://$HOME/svnrepos/testproject/branches/aBranch
AT THIS POINT YOU WANT TO PASS THE TESTS (IF THIS WAS NORESM)
alfg@pc4400:~/twoDevelopers/trunk$ svn commit -m "merged aBranch back to trunk"
=⇒ Observe that you don't get any conflict this time. Svn knows that the conflict is already resolved.
Other important points
- The merge is not completed until you commit!
- You have to know if you are doing a reintegrate merge or a merge from trunk (see noresm wiki)
- You can undo the merge with alfg@pc4400:~/twoDevelopers/aBranch$ svn revert -R .
- When you have done a “reintegrate merge”, consider your branch dead! (svn delete branchUrl -m “removed reintegrated branch aBranch”)
- If you insist on keeping reintegrated branches alive, there are two options:
- Start using another version control system
- Make sure you have latest svn version (version >= 1.7), Then read (and understand) http://svnbook.red-bean.com/en/1.7/svn.branchmerge.advanced.html#svn.branchmerge.advanced.reintegratetwice