How Git stores objects - Practice Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What type of Git object stores the content of a file?

In Git, different objects store different data. Which type of object stores the actual content of a file?

A Tag

B Blob

C Commit

D Tree

💡 Hint

Think about the object that holds raw file data without metadata.

A blob object stores the content of a file in Git. It does not contain file names or directory info.

💻 Command Output

intermediate

What is the output of 'git cat-file -t ' for a commit object?

You run the command git cat-file -t <object_hash> where <object_hash> is a commit object hash. What output do you expect?

A commit

B blob

C tree

D tag

💡 Hint

This command shows the type of the object by its hash.

The command git cat-file -t prints the type of the object. For a commit object, it prints commit.

❓ Configuration

advanced

How to verify the SHA-1 hash of a file matches its Git blob object?

You want to check if a file's content matches a Git blob object hash. Which command correctly computes the SHA-1 hash Git uses for blobs?

Git

echo -n "$(wc -c < file.txt)" | cat - file.txt | git hash-object --stdin

A git hash-object --stdin < file.txt

B sha1sum file.txt

C git hash-object file.txt

D git hash-object --stdin -w < file.txt

💡 Hint

Git hashes the file content with a header internally.

git hash-object file.txt computes the SHA-1 hash of the file content as Git stores it in a blob object.

❓ Troubleshoot

advanced

Why does 'git cat-file -p ' fail with 'fatal: Not a valid object name'?

You run git cat-file -p <hash> but get the error fatal: Not a valid object name. What is the most likely cause?

A The command requires root privileges

B The hash is a valid commit but corrupted

C The repository is not initialized

D The hash does not exist in the repository

💡 Hint

Check if the object hash is correct and present in the repo.

This error means Git cannot find the object with the given hash in the repository.

🔀 Workflow

expert

Order the steps Git uses to store a new file as an object

Put these steps in the correct order for how Git stores a new file as a blob object.

A 1,2,4,3

B 1,2,3,4

C 1,4,2,3

D 4,1,2,3

💡 Hint

Think about hashing, compressing, creating object, then writing to disk.

Git first calculates the hash, then compresses the data, creates the blob object, and finally writes it to the objects directory.