fast-import Git Command Guide

The git fast-import command is used to import Git data streams from stdin and write packfiles directly into the current repository. It is the backend for fast Git data importers that reads a mixed command/data stream.

git fast-import Syntax:

<frontend> | git fast-import [<options>]

Options:

Option	Description
—force	Force update modified branches
—quiet	Disable statistics output
—stats	Show basic statistics (default)
—allow-unsafe-features	Enable potentially dangerous features
—cat-blob-fd=	Write cat-blob responses to file descriptor
—date-format=	Specify date format for import
—done	Require done command at end of stream
—export-marks=	Export marks table to file
—import-marks=	Import marks from file
—import-marks-if-exists=	Import marks if file exists
—[no-]relative-marks	Use relative paths for marks files
—active-branches=	Max active branches (default 5)
—big-file-threshold=	Max size for delta creation
—depth=	Max delta depth (default 50)

Parameters:

Parameter	Description
(stdin)	Mixed command/data stream from frontend

Caution

Only use —allow-unsafe-features when you trust the source of the import stream. Always validate the import result and use marks for incremental imports.

git fast-import Command Samples:

Import from fast-export

git fast-export HEAD | git fast-import

Import current repository (creates a copy).

Incremental import with marks

git fast-export --import-marks=marks.txt --export-marks=marks.txt HEAD | git fast-import --import-marks=marks.txt --export-marks=marks.txt

Use marks for incremental bidirectional syncing.

Import with statistics

some-frontend | git fast-import --stats

Import with statistics display at completion.

Quiet import with cat-blob responses

frontend | git fast-import --quiet --cat-blob-fd=3 3>&-

Import quietly with blob queries sent to fd 3.

Force update existing branches

import-stream | git fast-import --force

Force import even if it would lose commits.

Generate reports on completion

git fast-import --stats < import.stream

Show detailed statistics after import completion.

Tip

Use marks files (—export-marks, —import-marks) for incremental repository updates and cross-referencing objects between import sessions.

How do I import using fast-export?

To import using fast-export, run:

git fast-export HEAD | git fast-import

How can I handle incremental imports?

To handle incremental imports, use marks:

git fast-import --import-marks=marks.txt --export-marks=marks.txt

How do I see import statistics?

To see import statistics, use the —stats option:

some-import-stream | git fast-import --stats

How can I force update branches?

To force update branches even if commits would be lost, use:

import-stream | git fast-import --force

How do I handle blob queries?

To handle blob queries via file descriptor, use —cat-blob-fd:

frontend | git fast-import --cat-blob-fd=3

How can I customize date formats?

To customize date formats for import, use —date-format:

import-stream | git fast-import --date-format=raw

Applications of the git fast-import command

1. Repository migration and conversion from other VCS
2. Bulk import of historical data from foreign sources
3. Repository reconstruction after corruption
4. Automated CI/CD pipeline data import
5. Creating mirror repositories from export dumps