Unit 7: Git - Fixing Mistakes/Time Traveling
Table of Contents
Fixing Mistakes/Time Traveling
Besides being able to track different versions of your projects, the cool part about Git is that you can undo things that you modify, stage, or commit. Read on to learn how to undo changes and “time travel” using Git.
git checkout
You can use git checkout to check out (view) a previous commit via the commit hash.
$ git checkout <commit hash>
For example:
$ git checkout ed19c25
To get back to the “present,” use git checkout master (or whatever branch you’re on).
Discard Changes
You can use the following to unmodify a modified file (discard changes):
$ git checkout -- <file>
For example, let’s say I added a line to hello.txt and I’ve decided that I actually don’t want to add that. I can do:
# cd into directory where hello.txt is located
$ git checkout -- hello.txt
git restore
You can use git restore --staged is the new way to unstage files.
$ git restore --staged
For the old way, see git reset.
git revert
Use git revert to “undo” a commit. Note that this does not actually delete the comment you are reverting; rather, it creates a new commit that effectively removes changes from the reverted commit.
Usage
$ git revert <commit>
Where <commit> is replaced by the commit hash of the commit you want to revert.
Example
In this example, I am reverting 85b4906, which added a file called message.txt. The commit message was "Add message".
$ git revert 85b4906
Removing message.txt
[master 31eff03] Revert "Add message"
1 file changed, 1 deletion(-)
delete mode 100644 message.txt
When completing a revert, Git will open your default editor so that you can write a revert commit message. For example:
Revert "Add message"
This reverts commit 85b4906b28651cad5fa440e98036e76c8bba38e8.
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch master
# Changes to be committed:
# deleted: message.txt
#
~
~
~
~
~
~
~
~
~
~
~
~
"~/Desktop/project-directory/.git/COMMIT_EDITMSG" 11L, 296C
Note that you may need to resolve conflicts when using git revert.
git reset
git reset is used to effectively “erase” history, resetting the state of your repository to a certain point in time. Because of this, make sure you are absolutely certain you do not need the commits that occurred after the reset point.
$ git reset <commit>
Where <commit> is replaced by the commit hash. All commits AFTER the given commit will be erased from the timeline. If you did this by accident, you can re-commit any files files right after.
Hard Reset
If you add the --hard flag, you will not be able to re-commit files.
$ git reset <commit> --hard
Soft Reset
Use the following command to remove files from a git commit:
$ git reset --soft HEAD~[int]
Where [int] is replaced by an integer. For example, HEAD~2 represents 2 commits before HEAD.
This move files modified in that commit to the staging area. At this point, you can remove files or unstage them (see below or git restore).
Unstage Files
To unstage a file, use the following:
$ git reset HEAD <file>