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.TH "bup\-gc" "1" "2026\-01\-28" "Bup 0.33.10+"
.SH NAME
bup\-gc \- remove unreferenced, unneeded data
.SH SYNOPSIS
bup gc [\-#|\-\-verbose] <\f[I]branch\f[R]|\f[I]save\f[R]\&...>
.SH DESCRIPTION
\f[CR]bup gc\f[R] removes (permanently deletes) unreachable data from
the repository, data that isn\[cq]t referred to directly or indirectly
by the current set of branches (backup sets) and tags.
But bear in mind that given deduplication, deleting a save and running
the garbage collector might or might not actually delete anything (or
reclaim any space).
.PP
With the current, proababilistic implementation, some fraction of the
unreachable data may be retained.
In exchange, the garbage collection should require less RAM than might
be required by some more precise approaches.
.PP
Typically, the garbage collector would be invoked after some set of
invocations of \f[CR]bup rm\f[R].
.PP
WARNING: This is one of the few bup commands that modifies your archive
in intentionally destructive ways.
Though if an attempt to \f[CR]join\f[R] or \f[CR]restore\f[R] the data
you still care about after a \f[CR]gc\f[R] succeeds, that\[cq]s a fairly
encouraging sign that the commands worked correctly.
(The \f[CR]dev/compare\-trees\f[R] command in the source tree can be
used to help test before/after results.)
.SH OPTIONS
.TP
\-\-threshold=N
only rewrite a packfile if it\[cq]s over N percent garbage and contains
no unreachable trees or commits.
The default threshold is 10%.
.TP
\-v, \-\-verbose
increase verbosity (can be used more than once).
With one \-v, bup prints every directory name as it gets backed up.
With two \-v, it also prints every filename.
.TP
\-\f[I]#\f[R], \-\-compress=\f[I]#\f[R]
set the compression level to # (a value from 0\-9, where 9 is the
highest and 0 is no compression).
The default is 1 (fast, loose compression).
.TP
\-\-ignore\-missing
report missing objects, but don\[cq]t stop the collection.
.SH EXIT STATUS
The exit status will be nonzero if there were any errors.
Encountering any missing object is considered an error.
.SH EXAMPLES
.IP
.EX
# Remove all saves of \[dq]home\[dq] and most of the otherwise unreferenced data.
$ bup rm home
$ bup gc
.EE
.SH SEE ALSO
\f[CR]bup\-rm\f[R](1) and \f[CR]bup\-fsck\f[R](1)
.SH BUP
Part of the \f[CR]bup\f[R](1) suite.
.SH AUTHORS
Rob Browning \c
.MT rlb@defaultvalue.org
.ME \c.