btrfs-receive

Synopsis

btrfs receive [options] <path>

or

btrfs receive --dump [options]

Description

Receive a stream of changes and replicate one or more subvolumes that were previously generated by btrfs send. The received subvolumes are stored to path, unless --dump option is given.

If --dump option is specified, btrfs receive will only do the validation of the stream, and print the stream metadata, one operation per line.

btrfs receive will fail in the following cases:

1. receiving subvolume already exists
2. previously received subvolume has been changed after it was received
3. default subvolume has changed or you didn’t mount the filesystem at the toplevel subvolume

A subvolume is made read-only after the receiving process finishes successfully (see Bugs below).

Options

-v

increase verbosity about performed actions, print details about each operation

-q|--quiet

suppress all messages except errors

-f <FILE>

read the stream from <FILE> instead of stdin,

-C|--chroot

confine the process to path using chroot(1)

-e

terminate after receiving an end cmd marker in the stream.

Without this option the receiver side terminates only in case of an error on end of file.

-E|--max-errors <NERR>

terminate as soon as NERR errors occur while stream processing commands from the stream

Default value is 1. A value of 0 means no limit.

-m <ROOTMOUNT>

the root mount point of the destination filesystem

By default the mountpoint is searched in /proc/self/mounts. If /proc is not accessible, eg. in a chroot environment, use this option to tell us where this filesystem is mounted.

--dump

dump the stream metadata, one line per operation

Does not require the path parameter. The filesystem remains unchanged.

Bugs

btrfs receive sets the subvolume read-only after it completes successfully. However, while the receive is in progress, users who have write access to files or directories in the receiving path can add, remove, or modify files, in which case the resulting read-only subvolume will not be an exact copy of the sent subvolume.

If the intention is to create an exact copy, the receiving path should be protected from access by users until the receive operation has completed and the subvolume is set to read-only.

Additionally, receive does not currently do a very good job of validating that an incremental send stream actually makes sense, and it is thus possible for a specially crafted send stream to create a subvolume with reflinks to arbitrary files in the same filesystem. Because of this, users are advised to not use btrfs receive on send streams from untrusted sources, and to protect trusted streams when sending them across untrusted networks.

Exit Status

btrfs receive returns a zero exit status if it succeeds. Non zero is returned in case of failure.

Availability

btrfs is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.

See Also

mkfs.btrfs(8), btrfs-send(8)

Referenced By

btrbk.conf(5), btrfs(8), btrfs-send(8).