Viewing History

After building up a series of commits, one of the most valuable things you can do is look back at what happened — who changed what, when, and why. Git's history is a permanent, queryable record of every decision made on a project. The primary tool for reading that record is git log.

The Basic Log — git log

Running git log with no arguments lists all commits in the current branch in reverse chronological order — most recent first:

git log

commit ca82a6dff817ec66f44342007202690a93763949
Author: Wariz <wariz@example.com>
Date:   Mon Mar 17 21:52:11 2024 -0700

    Change version number

commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Wariz <wariz@example.com>
Date:   Sat Mar 15 16:40:33 2024 -0700

    Remove unnecessary test

Each entry shows the full SHA-1 hash, the author name and email, the date, and the commit message. For a project with many commits, Git pipes the output through a pager — press q to exit.

Formatting the Output

git log has a rich set of options for controlling exactly what you see and how it is displayed.

--oneline — one commit per line

The most commonly used formatting flag. Each commit is condensed to a single line showing the abbreviated hash and the subject:

git log --oneline

ca82a6d Change version number
085bb3b Remove unnecessary test
a11bef0 Initial commit

This is invaluable for getting a quick overview of recent history without scrolling through walls of text.

-p or --patch — show the diff

Shows the full diff introduced by each commit — what lines were added and removed:

git log -p
git log -p -2    # Limit to the last 2 commits

Useful for code review or understanding exactly what a specific commit changed.

--stat — file-level statistics

Shows a summary of which files were modified in each commit and how many lines were added or removed:

git log --stat

commit ca82a6dff817ec66f44342007202690a93763949
Author: Wariz <wariz@example.com>
Date:   Mon Mar 17 21:52:11 2024

    Change version number

 Rakefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--pretty=format — custom output

For complete control over the output format:

git log --pretty=format:"%h - %an, %ar : %s"

ca82a6d - Wariz, 2 days ago : Change version number
085bb3b - Wariz, 4 days ago : Remove unnecessary test

Useful format specifiers:

--graph — branch visualisation

Adds an ASCII diagram of the branch and merge history alongside the log:

git log --oneline --graph

* 2d3acf9 Fix authentication bug
* 5e3ee11 Merge branch 'feature/login'
|\
| * 420eac9 Add login form component
* | 30e367c Update session timeout
|/
* d6016bc Initial project setup

This becomes particularly useful once you start working with branches — you can see at a glance where branches diverged and where they merged back.

Author vs. Committer

You may notice git log distinguishes between author and committer. The author is the person who originally wrote the change. The committer is the person who applied it to the repository. In a solo project they are always the same person. In collaborative projects — where patches are submitted and applied by a maintainer — they can differ.

Formatting Options Reference

Filtering the Output

git log is also a powerful search tool. You can narrow the output to exactly the commits you are looking for using filtering options.

By number of commits

Show only the most recent commits:

git log -3           # Last 3 commits
git log -10          # Last 10 commits

By date

git log --since=2.weeks                   # Last two weeks
git log --since="2024-01-01"              # Since a specific date
git log --until="2024-06-01"              # Before a specific date
git log --since="2 years 1 month ago"     # Relative date formats

By author

git log --author="Wariz"

Shows only commits where the author name matches the string. Partial matches work.

By commit message

git log --grep="authentication"

Shows only commits whose message contains the search term. Case-sensitive by default.

By changed content — the pickaxe

git log -S "functionName"

The -S option (known as the "pickaxe") shows only commits that added or removed a specific string from the codebase. This is extremely useful for tracking when a specific function, variable, or piece of logic was introduced or removed.

By file or directory

git log -- src/app.js              # Commits that touched this file
git log -- src/                    # Commits that touched anything in this directory

The -- separator tells Git that what follows is a path, not a branch name. Always place path filters last in the command.

Excluding merge commits

git log --no-merges

In active repositories, merge commits can make up a large percentage of the history without adding meaningful information. --no-merges removes them from the output.

Combining Options

Options can be combined freely to build precise queries:

# All commits by Wariz in the last month, excluding merges, one line each
git log --author="Wariz" --since=1.month --no-merges --oneline

# All commits that touched the auth module with their diffs
git log -p -- src/auth/

# Visual branch history for the last 20 commits
git log --oneline --graph -20

Inspecting a Single Commit — git show

To examine a specific commit in detail — its metadata and the full diff it introduced:

git show ca82a6d             # By abbreviated hash
git show HEAD                # The most recent commit
git show HEAD~2              # Two commits before HEAD

Output includes the commit metadata (author, date, message) followed by the complete diff.

Comparing Commits — git diff

While git log navigates history, git diff compares specific points within it:

git diff HEAD~3 HEAD                    # Changes over the last 3 commits
git diff abc123 def456                  # Changes between two specific commits
git diff main feature/login             # Changes between two branches
git diff HEAD~1 HEAD -- src/app.js      # Changes to a specific file between commits

Summary