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borg-diff(1) borg backup tool borg-diff(1)

Name

borg-diff - Finds differences between two archives.

SYNOPSIS

borg [common options] diff [options] ARCHIVE1 ARCHIVE2 [PATH...]

DESCRIPTION

This command finds differences (file contents, metadata) between ARCHIVE1 and ARCHIVE2.

For more help on include/exclude patterns, see the output of the borg_patterns command.

OPTIONS

See borg-common(1) for common options of Borg commands.

arguments

ARCHIVE1 name
ARCHIVE2 name
paths of items inside the archives to compare; patterns are supported.

options

only consider numeric user and group identifiers
override the check of chunker parameters
specify format for differences between archives (default: "{change} {path}{NL}")
Format output as JSON Lines.
Sort output by comma-separated fields (e.g., '>size_added,path').
Only compare differences in content (exclude metadata differences)

Include/Exclude options

exclude paths matching PATTERN
read exclude patterns from EXCLUDEFILE, one per line
include/exclude paths matching PATTERN
read include/exclude patterns from PATTERNFILE, one per line

EXAMPLES

$ borg diff archive1 archive2


    +17 B      -5 B [-rw-r--r-- -> -rwxr-xr-x] file1


   +135 B    -252 B file2
added           0 B file4
removed         0 B file3
$ borg diff archive1 archive2
{"path": "file1", "changes": [{"type": "modified", "added": 17, "removed": 5}, {"type": "mode", "old_mode": "-rw-r--r--", "new_mode": "-rwxr-xr-x"}]}
{"path": "file2", "changes": [{"type": "modified", "added": 135, "removed": 252}]}
{"path": "file4", "changes": [{"type": "added", "size": 0}]}
{"path": "file3", "changes": [{"type": "removed", "size": 0}]}
# Use --sort-by with a comma-separated list; sorts apply stably from last to first.
# Here: primary by net size change descending, tie-breaker by path ascending
$ borg diff --sort-by=">size_diff,path" archive1 archive2


    +17 B      -5 B [-rw-r--r-- -> -rwxr-xr-x] file1
removed         0 B file3
added           0 B file4


   +135 B    -252 B file2


NOTES

The FORMAT specifier syntax

The --format option uses Python's format string syntax <https://docs.python.org/3.10/library/string.html#formatstrings>.

Examples:

$ borg diff --format '{content:30} {path}{NL}' ArchiveFoo ArchiveBar
modified:  +4.1 kB  -1.0 kB    file-diff
...
# {VAR:<NUMBER} - pad to NUMBER columns left-aligned.
# {VAR:>NUMBER} - pad to NUMBER columns right-aligned.
$ borg diff --format '{content:>30} {path}{NL}' ArchiveFoo ArchiveBar


   modified:  +4.1 kB  -1.0 kB file-diff
...


The following keys are always available:

  • NEWLINE: OS dependent line separator
  • NL: alias of NEWLINE
  • NUL: NUL character for creating print0 / xargs -0 like output
  • SPACE: space character
  • TAB: tab character
  • CR: carriage return character
  • LF: line feed character

Keys available only when showing differences between archives:

  • path: archived file path
  • change: all available changes
  • content: file content change
  • mode: file mode change
  • type: file type change
  • owner: file owner (user/group) change
  • group: file group change
  • user: file user change
  • link: file link change
  • directory: file directory change
  • blkdev: file block device change
  • chrdev: file character device change
  • fifo: file fifo change
  • mtime: file modification time change
  • ctime: file change time change
  • isomtime: file modification time change (ISO 8601)
  • isoctime: file creation time change (ISO 8601)

What is compared

For each matching item in both archives, Borg reports:

  • Content changes: total added/removed bytes within files. If chunker parameters are comparable, Borg compares chunk IDs quickly; otherwise, it compares the content.
  • Metadata changes: user, group, mode, and other metadata shown inline, like "[old_mode -> new_mode]" for mode changes. Use --content-only to suppress metadata changes.
  • Added/removed items: printed as "added SIZE path" or "removed SIZE path".

Output formats

The default (text) output shows one line per changed path, e.g.:

+135 B    -252 B [ -rw-r--r-- -> -rwxr-xr-x ] path/to/file


JSON Lines output (--json-lines) prints one JSON object per changed path, e.g.:

{"path": "PATH", "changes": [


    {"type": "modified", "added": BYTES, "removed": BYTES},


    {"type": "mode", "old_mode": "-rw-r--r--", "new_mode": "-rwxr-xr-x"},


    {"type": "added", "size": SIZE},


    {"type": "removed", "size": SIZE}
]}


Sorting

Use --sort-by FIELDS where FIELDS is a comma-separated list of fields. Sorts are applied stably from last to first in the given list. Prepend ">" for descending, "<" (or no prefix) for ascending, for example --sort-by=">size_added,path". Supported fields include:

  • path: the item path
  • size_added: total bytes added for the item content
  • size_removed: total bytes removed for the item content
  • size_diff: size_added - size_removed (net content change)
  • size: size of the item as stored in ARCHIVE2 (0 for removed items)
  • user, group, uid, gid, ctime, mtime: taken from the item state in ARCHIVE2 when present
  • ctime_diff, mtime_diff: timestamp difference (ARCHIVE2 - ARCHIVE1)

Performance considerations

diff automatically detects whether the archives were created with the same chunker parameters. If so, only chunk IDs are compared, which is very fast.

SEE ALSO

borg-common(1)

Author

The Borg Collective

2025-12-24