lab 10 History

Goals

Learn how to view the history of the project.

Getting a listing of what changes have been made is the function of the git log command.

Execute:

git log

You should see …

Output:

$ git log
commit e4e3645637546103e72f0deb9abdd22dd256601e
Author: Jim Weirich <jim (at) edgecase.com>
Date:   Sat Jun 10 03:49:13 2023 -0400

    Added a comment

commit a6b268ebc6a47068474bd6dfb638eb06896a6057
Author: Jim Weirich <jim (at) edgecase.com>
Date:   Sat Jun 10 03:49:13 2023 -0400

    Added a default value

commit 174dfabb62e6588c0e3c40867295da073204eb01
Author: Jim Weirich <jim (at) edgecase.com>
Date:   Sat Jun 10 03:49:13 2023 -0400

    Using ARGV

commit f7c41d3ce80ca44e2c586434cbf90fea3a9009a5
Author: Jim Weirich <jim (at) edgecase.com>
Date:   Sat Jun 10 03:49:13 2023 -0400

    First Commit

Here is a list of all four commits that we have made to the repository so far.

One Line Histories

You have a great deal of control over exactly what the log command displays. I like the one line format:

Execute:

git log --pretty=oneline

You should see …

Output:

$ git log --pretty=oneline
e4e3645637546103e72f0deb9abdd22dd256601e Added a comment
a6b268ebc6a47068474bd6dfb638eb06896a6057 Added a default value
174dfabb62e6588c0e3c40867295da073204eb01 Using ARGV
f7c41d3ce80ca44e2c586434cbf90fea3a9009a5 First Commit

Controlling Which Entries are Displayed

There are a lot of options for selecting which entries are displayed in the log. Play around with the following options:

git log --pretty=oneline --max-count=2
git log --pretty=oneline --since='5 minutes ago'
git log --pretty=oneline --until='5 minutes ago'
git log --pretty=oneline --author=<your name>
git log --pretty=oneline --all

See man git-log for all the details.

Getting Fancy

Here’s what I use to review the changes made in the last week. I’ll add --author=jim if I only want to see changes I made.

git log --all --pretty=format:'%h %cd %s (%an)' --since='7 days ago'

The Ultimate Log Format

Over time, I’ve decided that I like the following log format for most of my work.

Execute:

git log --pretty=format:'%h %ad | %s%d [%an]' --graph --date=short

It looks like this:

Output:

$ git log --pretty=format:'%h %ad | %s%d [%an]' --graph --date=short
* e4e3645 2023-06-10 | Added a comment (HEAD -> main) [Jim Weirich]
* a6b268e 2023-06-10 | Added a default value [Jim Weirich]
* 174dfab 2023-06-10 | Using ARGV [Jim Weirich]
* f7c41d3 2023-06-10 | First Commit [Jim Weirich]

Let’s look at it in detail:

--pretty="..." defines the format of the output.
%h is the abbreviated hash of the commit
%d are any decorations on that commit (e.g. branch heads or tags)
%ad is the author date
%s is the comment
%an is the author name
--graph informs git to display the commit tree in an ASCII graph layout
--date=short keeps the date format nice and short

This is a lot to type every time you want to see the log. Fortunately we will learn about git aliases in the next lab.

Other Tools

Both gitx (for Macs) and gitk (any platform) are useful in exploring log history.