How to Dry Run Git Commands?

Git is used for version control in software development. Understanding the effects of Git commands before executing them can help prevent mistakes and ensure that your repository remains in a good state. This is where "dry running" Git commands become incredibly useful. A dry run simulates the execution of a command without making any changes, allowing you to see what would happen. This article will guide you through various ways to dry-run Git commands.

Why Use Dry Run in Git?

Dry running Git commands helps you:

• Prevent Mistakes: See the potential impact of commands before they make any changes.
• Learn Git: Understand what different Git commands do without affecting your repository.
• Debugging: Troubleshoot issues by simulating commands and observing their outputs.

Common Git Commands with Dry Run Options

1. git clean

The git clean command is used to remove untracked files from the working directory. To see what would be deleted without actually deleting the files, use the -n or --dry-run option:

git clean -n

This will list all files that would be removed without actually deleting them.

2. git add

While git add itself doesn't have a dry run option, you can use the git status command to preview which files will be staged:

git status

This shows the changes that will be staged if you run git add.

3. git rm

To see what would happen if you remove files, use the --dry-run option with git rm:

git rm --dry-run filename

This will show which files would be removed without actually deleting them.

4. git reset

For a dry run of git reset, you can use the --dry-run option to preview changes:

git reset --dry-run HEAD~1

This command will show you what would happen if you reset the last commit without actually performing the reset.

5. git revert

To preview the changes that would be made by reverting a commit, use --no-commit:

git revert --no-commit commit_id

This shows the changes that would be made without committing them.

Simulating Git Commands

1. Simulating git push

To see what would be pushed without actually pushing the changes, use the --dry-run option:

git push --dry-run

This simulates a push and shows you which branches would be updated without actually sending any data to the remote repository.

2. Simulating git pull

Although git pull doesn't have a built-in dry run option, you can simulate its effect using git fetch followed by git log to preview the changes:

git fetch
git log HEAD..origin/main

This fetches the latest changes from the remote repository and then shows the log of commits that would be pulled.

3. Simulating git merge

To see what would happen if you merge a branch, use git merge --no-commit:

git merge --no-commit branch-name

This prepares the merge and shows you the changes without actually committing the merge.

Custom Dry Runs with Aliases

You can create Git aliases to simulate dry runs for commands that don’t have built-in dry run options. For example, to create a dry run alias for git commit, you could use:

git config --global alias.commit-dry "commit --dry-run"

Now, you can use git commit-dry to simulate a commit without actually creating one.