Usually rebasing commits that have already been pushed is strongly discouraged.
The main problem with rebasing pushed commits is that if another contributor has based their work on one of the commits which is subsequently rebased, this effectively creates a parallel timeline in which the commits on which their work stands never existed.
Given that we created our own fork, and branched within that fork, it's safe to assume that nobody will be using it as a baseline. We can therefore rebase without causing the universe to implode.
That said, here's the process...
First, fetch any upstream changes...
$ git fetch upstream
and change to your development branch...
$ git checkout dev-branch1
Now if you want to rebase your commits on top without making any additional changes you can use the command:
$ git rebase upstream/master
If you want to edit a commit message you will need to use the interactive rebase.
$ git rebase -i origin/dev-branch1
Your default text editor will launch and display something like...
pick d8ff6b0 Update readme
pick 80309d3 Fixed tpyo
pick d38fb35 Deleted line
# Rebase 0bee19a..d38fb35 onto 0bee19a (3 command(s))
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
# d, drop = remove commit
To change a commit comment, select the line you wish to change by replacing "pick" with "r" and then saving the document.
pick d8ff6b0 Update readme
r 80309d3 Fixed tpyo
pick d38fb35 Deleted line
Your text editor will open a new window allowing you to change the commit message...
Fixed typo
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
Save and quit to apply your changes.
If you want to squash multiple commits together into a single commit you will need to use the interactive rebase.
$ git rebase -i origin/dev-branch1
Your default text editor will launch and display something like...
pick d8ff6b0 Update readme
pick 80309d3 Fixed tpyo
pick d38fb35 Deleted line
# Rebase 0bee19a..d38fb35 onto 0bee19a (3 command(s))
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
# d, drop = remove commit
To change a commit comment, select the lines you wish to squash by replacing "pick" with "s" and saving the document.
For example:
pick d8ff6b0 Update readme
s 80309d3 Fixed tpyo
s d38fb35 Deleted line
If all goes well your text editor will open and display something like...
# This is a combination of 3 commits.
# The first commit's message is:
Update readme
# This is the 2nd commit message:
Fixed typo
# This is the 3rd commit message:
Deleted line
Comment out any of the commit messages you no longer require, enter a new message then save and quit.
###Aborting a rebase.
If you feel uncertain at any stage, you can abort a rebase using the following command:
$ git rebase --abort
After rebasing you will not be able to push your changes back to your branch. You will need to use the --force option. There's no going back if you make a mistake so be sure about what you are pushing, and that you are pushing the correct branch to the correct remote.
$ git push -f origin dev-branch1:dev-branch1
The above command will replace origin/dev-branch1 with the contents of dev-branch1, including all history.