.SH SYNOPSIS
.B notmuch compact
+.RI "[ --quiet ]"
+.RI "[ --backup=<" directory "> ]"
.SH DESCRIPTION
The compacted database is built in a temporary directory and is later
moved into the place of the origin database. The original uncompacted
-database is preserved to be deleted by the user as desired.
+database is discarded, unless the
+.BR "\-\-backup=" <directory>
+option is used.
Note that the database write lock will be held during the compaction
process (which may be quite long) to protect data integrity.
+Supported options for
+.B compact
+include
+
+.RS 4
+.TP 4
+.BR "\-\-backup=" <directory>
+
+Save the current database to the given directory before replacing it
+with the compacted database. The backup directory must not exist and
+it must reside on the same mounted filesystem as the current database.
+
+.RE
+
+.RS 4
+.TP 4
+.BR \-\-quiet
+
+Do not report database compaction progress to stdout.
+
+.RE
+
.RE
.SH ENVIRONMENT
The following environment variables can be used to control the