Git write-tree

Resources

• Part 2: Blobs and trees – alexwlchan

From a-plumbers-guide-to-git.

write-tree is a plumbing command.

.
├── animals.txt
├── animals_copy.txt
└── underwater
    ├── d.txt
    └── e.txt

git update-index --add animals.txt
git update-index --add underwater/d.txt
git update-index --add underwater/e.txt

# This will create 3 objects under .git/objects (all blobs)

git write-tree
# 56cce7867ca48d55b3fe5ad49c92f16e648d6225
# This will create 2 more objects under .git/objects (both trees)

git cat-file -p 56cce7867ca48d55b3fe5ad49c92f16e648d6225
# 100644 blob 5e7d431e528424312265caea6b150ff54023ab92    animals.txt
# 040000 tree 8972388aa2e995eb4fa0247ccc4e69144f7175b9    underwater

git cat-file -t 5e7d431e528424312265caea6b150ff54023ab92
# blob
git cat-file -t 8972388aa2e995eb4fa0247ccc4e69144f7175b9
# tree

git cat-file -p 8972388aa2e995eb4fa0247ccc4e69144f7175b9
# 100644 blob cb68066907dd99eb75642bdbd449e1647cc78928    d.txt
# 100644 blob 9968b7362a7c97e237c74276d65b68ca20e03c47    e.txt

write-tree stores a list of pointers to other objects (one per row).

The four columns in each row are: - 100644 is the file permissions. Git only distinguishes between 644 (non-executable) and 755 (executable). - blob is the type of the object (more on that below). - The ID of the file contents (which are saved with git hash-object) - animals.txt is the name of that file.