Making Changes
git log
Shows a history of commits, including author, date, and commit message.
git log --oneline
Sample output:
* 7f71eade (HEAD -> main) Adding fresh data for the survey.
* 1182c282 Added CSV data file
* 36b761e4 Added reminder to cite funding sources.
* e39ecc89 Added summary report file.
To find which commit caused an issue, note the first 6-8 characters of the commit hash, then use git show to inspect it:
git show 36b761e4
To look at the git history of a particular file:
git log sample-report.md
Customize log output
To look at the git history of a particular file:
git log sample-report.md
To limit the number of commits displayed:
git log -3 # limit to 3 commits
Restrict log by date:
git log --since='Month Day Year'
As an example:
-
Commits since 27 May 2019:
git log --since='May 27 2019' -
Commits between April 19 to June 30 2019:
git log --since='April 19 2019' --until='June 30 2019
View changes
Shows differences between the working directory and the latest commit.
git diff -r HEAD
Sample Output:
diff --git a/report.md b/report.md
index e69de29..d95f3ad 100644
--- a/report.md
+++ b/report.md
@@ -1,3 +1,5 @@
+Reminder: Cite funding sources.
Data analysis results:
- Survey responses processed.
HEAD
In git show HEAD~3, the 3 represents how many commits to go back from HEAD (the latest commit).
HEAD~1→ One commit before the latestHEAD~2→ Two commits before the latestHEAD~3→ Three commits before the latest
So, git show HEAD~3 displays details of the commit that is three commits before the current HEAD.
If you run:
git log --oneline
Consider the sample commits below:
$ git log --oneline
a1b2c3d4 Add user authentication feature
e5f6g7h8 Fix database connection issue
i9j0k1l2 Update API endpoint response format
m3n4o5p6 Initial project setup
Here, using HEAD~3 will refer to m3n4o5p6, the fourth commit in the list, because we count back three steps from HEAD.
Comparing two commits
Shows differences between two commits.
git diff 123456 asdfg123
Alternatively, compare commits using relative references:
git show HEAD~3 HEAD~2
git annotate
This is used to show who last modified each line of a file along with commit details.
git annotate test-file.md
Sample output:
a1b2c3d4 (Alice 2024-02-10 08:30:12 +0000 1) # Initial commit
a1b2c3d4 (Alice 2024-02-10 08:30:12 +0000 2) Added authentication module
e5f6g7h8 (Bob 2024-02-11 14:15:47 +0000 3) Refactored database connection
i9j0k1l2 (Charlie 2024-02-12 16:50:33 +0000 4) Updated API response format
git blame
Similar to git annotate, but is the standard command for tracking line modifications.
git blame test-file.md
Sample output:
a1b2c3d4 (Alice 2024-02-10 08:30:12 +0000 1) # Initial commit
a1b2c3d4 (Alice 2024-02-10 08:30:12 +0000 2) Added authentication module
e5f6g7h8 (Bob 2024-02-11 14:15:47 +0000 3) Refactored database connection
i9j0k1l2 (Charlie 2024-02-12 16:50:33 +0000 4) Updated API response format
Unstaging changes
Undo changes before committing by resetting files from the staging area.
git reset HEAD sample-report.csv
To unstage all files:
git reset HEAD
Undo changes to unstaged file
Discard changes made to a file before staging. This is also the same command used to revert the file to an old version.
git checkout -- sample-report.csv
git checkout reverts a file to its last committed version.
⚠️ This action is irreversible—changes will be lost permanently.
To undo changes in all unstaged files:
git checkout .
To revert to a version from a specific commit:
git checkout asdety890 sample-report.csv ## asdety890 is the hash
To restore the entire repo to a previous state, specify the commit without specifying any file.
git checkout 123hjklsd ## 123hjklsd is the hash
Cleaning the repository
To see which files are not being tracked:
git clean -n
Next, proceed to deleting those files:
git clean -f
⚠️ This action is irreversible - files will be removed for good.