Exercise - Dealing with “Push Reject”

When multiple developers work on the same project, the message error: failed to push some refs ... often occurs during git push, the so-called Push Reject.

This is not a bad thing. It simply means that in the origin repository commits were found that are not yet integrated locally.

You can fetch and integrate the changes with git pull.

Or you can first fetch the changes with git fetch to examine them, and later decide what you want to do with them.

Tips

  • git push: Transfers commits to origin.
  • git fetch: Fetches commits, but does not change the workspace and local branch
  • git pull: Fetches and integrates commits.
  • git log A..B shows “what B did”.
    Or more precisely: Those commits from the history of B that are not yet contained in A.
  • git diff A B shows the differences between A and B
    (symmetrical diff)
  • git diff A...B shows the changes of side B.
    Or more precisely: The diff between the last common ancestor and B.
    (asymmetrical diff)

Setup

  • You are working on a project apollo, that was created by your colleague Anja.
  • You are supposed to improve the file frontend.java, while Anja continues to work on the file backend.java.

If Anja uploads her changes before you, you will experience a Push Reject.

Directories

  • ./ Main directory for this exercise
    • blessed-apollo.git/ The shared (blessed) repository is here.
    • anjas-apollo/ Anja works here.
    • my-apollo/ You work here.

Step 0 - START 

$ cd my-apollo


Step 1 - Create local commit(s)

Start in directory git-uebungen/aufgaben/zusammenarbeit-push-rejected/my-apollo.

Edit the file frontend.java and create (at least) one commit with the changes. Then check with git status if the workspace is clean.

Step 2 - Try to push

Start in directory git-uebungen/aufgaben/zusammenarbeit-push-rejected/my-apollo.

Now try to push your changes.

Step 3 - (optional) Analyze problem

Start in directory git-uebungen/aufgaben/zusammenarbeit-push-rejected/my-apollo.

First fetch the changes without integrating (fetch), and let Anja’s changes be shown to you.

  • Which commits did Anja make (log)?
  • What are the differences between your and Anja’s version (symmetrical diff)?
  • What changes did Anja make (asymmetrical diff)?

Step 4 - Integrate foreign changes

Start in directory git-uebungen/aufgaben/zusammenarbeit-push-rejected/my-apollo.

Integrate the changes with pull and then look at the commit graph.

Step 5 - Push again

Start in directory git-uebungen/aufgaben/zusammenarbeit-push-rejected/my-apollo.

my-apollo $ cd ..


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