bup(1) Bup 0.34+

Avery Pennarun

2026-09-01

NAME

bup - Backup program using rolling checksums and git file formats

SYNOPSIS

bup [global options…] <command> [options…]

DESCRIPTION

bup is a program for making backups of your files using the git file format.

Unlike git(1) itself, bup is optimized for handling huge data sets including individual very large files (such a virtual machine images). However, once a backup set is created, it can still be accessed using git tools.

Subcommands are described in separate man pages. For example bup-init(1) covers bup init.

GLOBAL OPTIONS

--version
print bup’s version number. Equivalent to bup version.
-d, --bup-dir=BUP_DIR
use the given BUP_DIR parameter as the bup repository location, instead of reading it from the $BUP_DIR environment variable or using the default ~/.bup location.

PRIMARY COMMANDS

bup-init(1)
Initialize a bup repository
bup-index(1)
Create or display the index of files to back up
bup-save(1)
Save files into a backup set (note: run “bup index” first)
bup-restore(1)
Extract files from a backup set
bup-fsck(1)
Check backup sets for damage and add recovery information
bup-on(1)
Index/save/split/get/… a remote machine
bup-help(1)
Print detailed help for the given command

INSPECTION COMMANDS

bup-ls(1)
Browse the files in your backup sets
bup-fuse(1)
Mount your backup sets as a filesystem
bup-web(1)
Launch a web server to examine backup sets
bup-ftp(1)
Browse backup sets using an ftp-like client

MANIPULATION COMMANDS

bup-gc(1)
Remove unreferenced, unneeded data
bup-get(1)
Transfer/transform items between/within repositories
bup-prune-older(1)
Remove older saves
bup-rm(1)
Remove references to archive content

IMPORT COMMANDS

bup-import-duplicity(1)
Import from duplicity(1)
bup-import-rdiff-backup(1)
Import from rdiff-backup(1)
bup-import-rsnapshot(1)
Import from rsnapshot(1)

OTHER COMMANDS

bup-cat-file(1)
Extract archive content
bup-drecurse(1)
Recursively list files in your filesystem
bup-features(1)
Report the current status and capabilities of bup itself
bup-join(1)
Retrieve a file backed up using bup-split(1)
bup-server(1)
The server side of the bup client-server relationship
bup-split(1)
Split a single file into its own backup set
bup-tag(1)
Tag a commit in the bup repository
bup-validate-object-links(1)
Scan the repository for broken object links
bup-validate-ref-links(1)
Check repository refs for links to missing objects
bup-version(1)
Report the version number of your copy of bup.

ESOTERIC COMMANDS

bup-bloom(1)
Generates, regenerates, updates bloom filters
bup-damage(1)
Deliberately destroy data
bup-margin(1)
Determine how close your bup repository is to armageddon
bup-memtest(1)
Test bup memory usage statistics
bup-meta(1)
Create or extract a metadata archive
bup-midx(1)
Index objects to speed up future backups
bup-random(1)
Generate a stream of random output
bup-tick(1)
Wait for up to one second.

REMOTE OPTIONS

Some options (currently just --remote) allow the specification of a remote path as either a URL (see REPOSITORY URLS below) or a [*user*@]*host*:[*path*].

For either format, when there is no path, the default path on the server will be used (BUP_DIR if set in the remote environment or ~/.bup), and SSH settings for the connection can be provided by a custom host in your ~/.ssh/config file (ssh_config(5)).

The argument is treated as a URL if it begins with a syntactically valid URL scheme prefix that contains an “authority” (meaning that it begins with SCHEME:// as ssh://... does), and the scheme must be either ssh or bup; others will be rejected.

For the [*user*@]*host*:[*path*] syntax, if there is an @ symbol, then everything before the rightmost @ is included in the user so -r x@y@z indicates user x@y, host z. The host must always be followed by a colon, and anything after the first colon is the path.

For fully general purposes, prefer URLs to [*user*@]*host*:[*path*], so that there is no potential ambiguity. For example, consider the (unlikely) case where ssh://x/y is generated for a host named ssh and path //x/y, which would be interpreted as a URL with host x and path /y.

REPOSITORY URLS

Bup supports the following URL schemes (i.e. scheme:) for referring to a repository. Note that the term “authority” below just means the URL section after the scheme:// and before the path, for example the “user@host:port” of an SSH URL.

As an exception to the standard, a scheme may be “path-oriented”, which means that there is no separate query or fragment. Anything after the (optional) authority is taken as the “path” and the constituent bytes are not decoded (e.g. percent decoded). This allows URLs provided on the command line to work naturally. So ssh://host/x?z has a path of /x?z.

And since URLs with an authority cannot represent relative paths, path-oriented schemes interpret a leading /./ as a relative path. So ssh://host/./x, file:///./x, and file:/./x all indicate the path x.

ssh:
A path-oriented scheme (see above) that specifies access to a repository via a bup-server(1) launched on a host via SSH. This scheme has syntax and semantics matching a typical ssh: URL, including support for a user and port (e.g. ssh://user@host:2222/some/repo), and the user and host can be percent encoded.
bup:
A path-oriented scheme (see above) specifying a direct network connection to to an existing bup-server(1). Otherwise identical to ssh:, except that it does not support a user. This connection has no authentication or encryption of its own so it’s unlikely you’ll want to use it; prefer file: or :ssh:.
file:
A path-oriented scheme (see above) that specifies a repository’s filesystem path. This scheme has syntax and semantics matching a typical file: URL, except that it only allows an empty authority (i.e. no user, host, etc.). In most cases, you will probably want to include the empty authority so you don’t have to consider the contents of the path carefully, i.e. use file://PATH or ssh://user@hostPATH when the PATH begins with a slash, and file:///./PATH or ssh://user@host/./PATH when it doesn’t. It is possible to omit the authority, but only if the path does not begin with two slashes. For example file:/ and file:some/where are fine, but file://some/where is not because some will be read as the authority.

ENVIRONMENT

BUP_ASSUME_GIT_VERSION_IS_FINE
If set to true, yes, or 1, assume the version of git in the path is acceptable.

SEE ALSO

The README file from the bup distribution, git(1), and http://bup.github.io