GIT: Using Git reset

25.1. Moving the HEAD and branch pointer

Sometimes you want to change the commmit your branch pointer is pointing to. The git reset command allows you to manually set the current HEAD pointer (and its associated branch) to a specified commit. This is for example useful to undo a particular change or to build up a different commit history.

All commits which were originally pointed to by the HEAD pointer and the commit pointed to by HEAD after the reset, are reseted, e.g., not directly visible anymore from the current HEAD and branch pointer.

Via parameters you can decide what you happen to the changes in the working tree and changes which were included in the commits between the original commit and the commit now referred to by the HEAD pointer. As a reminder, the working tree contains the files and the staging area contains the changes which are marked to be included in the next commit. Depending on the specified parameters the git reset command performs the following:

1. If you specify the --soft parameter, the git reset command moves the HEAD pointer. Changes in the working tree will be left unchanged and all changes which were commited included in commits which are reseted are staged.
2. If you specify the --mixed parameter (the default), the git reset command moves the HEAD pointer and resets the staging area to the new HEAD. Any file change between the original commit and the one you reset to shows up as modifications (or untracked files) in your working tree. Use this option to remove commits but keep all the work you have done. You can do additional changes, stage changes and commit again. This way you can build up a different commit history.
3. If you specify the --hard parameter, the git reset command moves the HEAD pointer and resets the staging area and the working tree to the new HEAD. This effectively removes the changes you have done between the original commit and the one you reset to.

Via parameters you can define if the staging area and the working tree is updated. These parameters are listed in the following table.

Table 2. git reset options

Reset	Branch pointer	Working tree	Staging area
soft	Yes	No	No
mixed (default)	Yes	No	Yes
hard	Yes	Yes	Yes

The git reset command does not remove untracked files. 

25.2. Not moving the HEAD pointer with git reset

If you specify a path via the git reset [path] command, Git does not move the HEAD pointer. It updates the staging area or also the working tree depending on your specified option.