git blame for line-by-line history - Step-by-Step Execution

Process Flow - git blame for line-by-line history

Start: Select file

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Run git blame

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Git finds last commit for each line

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Display line with commit info

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User reads who changed each line and when

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End

The flow shows how git blame takes a file, finds the last commit for each line, and displays that info line-by-line.

Execution Sample

Git

git blame example.txt

Shows who last changed each line in example.txt with commit info.

Process Table

Step	Action	Input/Line	Git Operation	Output/Result
1	Select file to blame	example.txt	Prepare file for blame	File example.txt ready
2	Run git blame	git blame example.txt	Git reads file lines	Starts processing lines
3	Process line 1	Line 1 content	Find last commit touching line 1	Commit abc123 by Alice, date
4	Process line 2	Line 2 content	Find last commit touching line 2	Commit def456 by Bob, date
5	Process line 3	Line 3 content	Find last commit touching line 3	Commit abc123 by Alice, date
6	Display results	All lines processed	Show line with commit info	Lines shown with commit, author, date
7	End	-	-	User sees full line-by-line history

💡 All lines processed and annotated with last commit info

Status Tracker

Variable	Start	After Line 1	After Line 2	After Line 3	Final
current_line	0	1	2	3	3
commit_info	{}	{line1: abc123, Alice}	{line1: abc123, Alice; line2: def456, Bob}	{line1: abc123, Alice; line2: def456, Bob; line3: abc123, Alice}	{line1: abc123, Alice; line2: def456, Bob; line3: abc123, Alice}

Key Moments - 3 Insights

Why does git blame show different commit IDs for different lines in the same file?

Because git blame finds the last commit that changed each specific line, so different lines can have different commit histories as shown in steps 3-5 of the execution table.

What if a line was never changed after the first commit?

Git blame will show the original commit that introduced that line, as seen in line 1 and 3 where commit abc123 appears, meaning those lines were last changed in that commit.

Does git blame modify the file or repository?

No, git blame only reads the history and shows info; it does not change the file or repository state, confirmed by the final step in the execution table.

Visual Quiz - 3 Questions

Look at the execution table, what commit does line 2 belong to?

A abc123 by Alice

B def456 by Bob

C xyz789 by Carol

D No commit found

💡 Hint

Check step 4 in the execution table where line 2 is processed.

At which step does git blame finish processing all lines?

A Step 6

B Step 5

C Step 7

D Step 3

💡 Hint

Look for the step where results are displayed after processing all lines.

If a new line is added and committed, how would the variable 'current_line' change?

A It would stay the same

B It would decrease

C It would increase by 1

D It would reset to 0

💡 Hint

Refer to the variable_tracker showing current_line increments after each line processed.

Concept Snapshot

git blame syntax: git blame <file>
Shows last commit info for each line in the file.
Each line is annotated with commit ID, author, and date.
Does not change file or repo, only reads history.
Useful to find who last changed a specific line.

Full Transcript

Git blame is a command that shows who last changed each line in a file. The process starts by selecting the file, then running git blame on it. Git reads each line and finds the last commit that modified that line. It then displays the file lines with commit ID, author, and date next to each line. This helps users understand the history of changes line-by-line without modifying the file or repository. The execution table shows each step from selecting the file to displaying the results. Variables like current_line and commit_info track progress and data collected. Key moments clarify why different lines have different commits and confirm that git blame is read-only. The visual quiz tests understanding of commit assignments, processing steps, and variable changes. The snapshot summarizes the command usage and behavior for quick reference.