mirror of https://github.com/djcb/mu.git
252 lines
9.5 KiB
Groff
252 lines
9.5 KiB
Groff
.TH MU-INDEX 1 "July 2016" "User Manuals"
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.SH NAME
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mu index \- index e-mail messages stored in Maildirs
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.SH SYNOPSIS
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.B mu index [options]
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.SH DESCRIPTION
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\fBmu index\fR is the \fBmu\fR command for scanning the contents of Maildir
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directories and storing the results in a Xapian database. The data can then be
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queried using
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.BR mu-find(1)\.
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\fBindex\fR understands Maildirs as defined by Daniel Bernstein for
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qmail(7). In addition, it understands recursive Maildirs (Maildirs
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within Maildirs), Maildir++. It can also deal with VFAT-based Maildirs
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which use '!' as the separators instead of ':'.
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E-mail messages which are not stored in something resembling a maildir
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leaf-directory (\fIcur\fR and \fInew\fR) are ignored, as are the cache
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directories for \fInotmuch\fR and \fIgnus\fR, and any dot-directory.
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Symlinks are not followed.
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If there is a file called \fI.noindex\fR in a directory, the contents of that
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directory and all of its subdirectories will be ignored. This can be useful to
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exclude certain directories from the indexing process, for example directories
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with spam-messages.
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If there is a file called \fI.noupdate\fR in a directory, the contents of that
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directory and all of its subdirectories will be ignored, unless we do a full
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rebuild (with \fB--rebuild\fR). This can be useful to speed up things you have
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some maildirs that never change. Note that you can still search for these
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messages, this only affects updating the database.
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There also the \fB--lazy-check\fR which can greatly speed up indexing;
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see below for details.
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The first run of \fBmu index\fR may take a few minutes if you have a
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lot of mail (tens of thousands of messages). Fortunately, such a full
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scan needs to be done only once; after that it suffices to index the
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changes, which goes much faster. See the 'Note on performance
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(i,ii,iii)' below for more information.
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The optional 'phase two' of the indexing-process is the removal of messages
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from the database for which there is no longer a corresponding file in the
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Maildir. If you do not want this, you can use \fB\-n\fR, \fB\-\-nocleanup\fR.
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When \fBmu index\fR catches one of the signals \fBSIGINT\fR, \fBSIGHUP\fR or
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\fBSIGTERM\fR (e.g., when you press Ctrl-C during the indexing process), it
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tries to shutdown gracefully; it tries to save and commit data, and close the
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database etc. If it receives another signal (e.g., when pressing Ctrl-C once
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more), \fBmu index\fR will terminate immediately.
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.SH OPTIONS
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Note, some of the general options are described in the \fBmu(1)\fR man-page
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and not here, as they apply to multiple mu commands.
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.TP
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\fB\-m\fR, \fB\-\-maildir\fR=\fI<maildir>\fR
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starts searching at \fI<maildir>\fR. By default, \fBmu\fR uses whatever the
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\fBMAILDIR\fR environment variable is set to; if it is not set, it tries
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\fI~/Maildir\fR. See the note on mixing sub-maildirs below.
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.TP
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\fB\-\-my-address\fR=\fI<my-email-address>\fR
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specifies that some e-mail address is 'my-address' (\fB\-\-my-address\fR can
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be used multiple times). This is used by \fBmu cfind\fR -- any e-mail address
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found in the address fields of a message which also has
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\fI<my-email-address>\fR in one of its address fields is considered a
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\fIpersonal\fR e-mail address. This allows you, for example, to filter out
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(\fBmu cfind --personal\fR) addresses which were merely seen in mailing list
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messages.
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.TP
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\fB\-\-lazy-check\fR
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in lazy-check mode, \fBmu\fR does not consider messages for which the
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time-stamp (ctime) of the directory they reside in has not changed
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since the previous indexing run. This is much faster than the non-lazy
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check, but won't update messages that have change (rather than having
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been added or removed), since merely editing a message does not update
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the directory time-stamp. Of course, you can run \fBmu-index\fR
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occasionally without \fB\-\-lazy-check\fR, to pick up such messages.
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.TP
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\fB\-\-nocleanup\fR
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disables the database cleanup that \fBmu\fR does by default after indexing.
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.TP
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\fB\-\-rebuild\fR
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clear all messages from the database before indexing. \fB\-\-rebuild\fR
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guarantees that after the indexing has finished, there are no 'old' messages
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in the database anymore, which is not true with \fB\-\-reindex\fR when
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indexing only a part of messages (using \fB\-\-maildir\fR). For this reason,
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it is necessary to run \fBmu index \-\-rebuild\fR when there is an upgrade in
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the database format. \fBmu index\fR will issue a warning about this.
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.TP
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\fB\-\-autoupgrade\fR
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automatically use \fB\-y\fR, \fB\-\-empty\fR
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when \fBmu\fR notices that the database version is not up-to-date. This option
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is for use in cron scripts and the like, so they won't require any user
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interaction, even when mu introduces a new database version.
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.TP
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\fB\-\-xbatchsize\fR=\fI<batch size>\fR
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set the maximum number of messages to process in a single Xapian
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transaction. In practice, this option is only useful if you find that \fBmu\fR
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is running out of memory while indexing; in that case, you can set the batch
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size to (for example) 1000, which will reduce memory consumption, but also
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substantially reduce the indexing performance.
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.TP
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\fB\-\-max-msg-size\fR=\fI<max msg size>\fR
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set the maximum size (in bytes) for messages. The default maximum
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(currently at 500Mb) should be enough in most cases, but if you
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encounter warnings from \fBmu\fR about ignoring messsage because they
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are too big, you may want to increase this. Note that the reason for
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having a maximum size is that big messages require big memory
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allocations, which may lead to problems.
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.B NOTE:
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It is not recommended to mix maildirs and sub-maildirs within the hierarchy
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in the same database; for example, it's better not to index both with
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\fB\-\-maildir\fR=~/MyMaildir and \fB\-\-maildir\fR=~/MyMaildir/foo, as this
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may lead to unexpected results when searching with the 'maildir:' search
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parameter (see below).
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.SS A note on performance (i)
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As a non-scientific benchmark, a simple test on the author's machine (a
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Thinkpad X61s laptop using Linux 2.6.35 and an ext3 file system) with no
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existing database, and a maildir with 27273 messages:
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.nf
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$ sudo sh -c 'sync && echo 3 > /proc/sys/vm/drop_caches'
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$ time mu index --quiet
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66,65s user 6,05s system 27% cpu 4:24,20 total
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.fi
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(about 103 messages per second)
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A second run, which is the more typical use case when there is a database
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already, goes much faster:
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.nf
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$ sudo sh -c 'sync && echo 3 > /proc/sys/vm/drop_caches'
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$ time mu index --quiet
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0,48s user 0,76s system 10% cpu 11,796 total
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.fi
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(more than 56818 messages per second)
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Note that each test flushes the caches first; a more common use case might
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be to run \fBmu index\fR when new mail has arrived; the cache may stay
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quite 'warm' in that case:
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.nf
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$ time mu index --quiet
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0,33s user 0,40s system 80% cpu 0,905 total
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.fi
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which is more than 30000 messages per second.
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.SS A note on performance (ii)
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As per June 2012, we did the same non-scientific benchmark, this time with an
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Intel i5-2500 CPU @ 3.30GHz, an ext4 file system and a maildir with 22589
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messages. We start without an existing database.
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.nf
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$ sudo sh -c 'sync && echo 3 > /proc/sys/vm/drop_caches'
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$ time mu index --quiet
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27,79s user 2,17s system 48% cpu 1:01,47 total
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.fi
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(about 813 messages per second)
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A second run, which is the more typical use case when there is a database
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already, goes much faster:
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.nf
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$ sudo sh -c 'sync && echo 3 > /proc/sys/vm/drop_caches'
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$ time mu index --quiet
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0,13s user 0,30s system 19% cpu 2,162 total
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.fi
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(more than 173000 messages per second)
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.SS A note on performance (iii)
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As per July 2016, we did the same non-scientific benchmark, again with
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the Intel i5-2500 CPU @ 3.30GHz, an ext4 file system. This time, the
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maildir contains 72525 messages.
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.nf
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$ sudo sh -c 'sync && echo 3 > /proc/sys/vm/drop_caches'
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$ time mu index --quiet
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40,34s user 2,56s system 64% cpu 1:06,17 total
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.fi
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(about 1099 messages per second).
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As shown, \fBmu\fR has been getting faster with each release, even
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with relatively expensive new features such as text-normalization (for
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case-insensitve/accent-insensitive matching). The profiles are
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dominated by operations in the Xapian database now.
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.SH FILES
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By default, \fBmu index\fR stores its message database in \fI~/.mu/xapian\fR;
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the database has an embedded version number, and \fBmu\fR will automatically
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update it when it notices a different version. This allows for automatic
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updating of \fBmu\fR-versions, without the need to clear out any old
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databases.
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However, note that versions of \fBmu\fR before 0.7 used a different scheme,
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which puts the database in \fI~/.mu/xapian\-<version>\fR. These older
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databases can safely be deleted. Starting from version 0.7, this manual
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cleanup should no longer be needed.
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\fBmu\fR stores logs of its operations and queries in \fI<muhome>/mu.log\fR
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(by default, this is \fI~/.mu/mu.log\fR). Upon startup, \fBmu\fR checks the
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size of this log file. If it exceeds 1 MB, it will be moved to
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\fI~/.mu/mu.log.old\fR, overwriting any existing file of that name, and start
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with an empty log file. This scheme allows for continued use of \fBmu\fR
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without the need for any manual maintenance of log files.
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.SH ENVIRONMENT
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\fBmu index\fR uses \fBMAILDIR\fR to find the user's Maildir if it has not
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been specified explicitly with \fB\-\-maildir\fR=\fI<maildir>\fR. If
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\fBMAILDIR\fR is not set, \fBmu index\fR will try \fI~/Maildir\fR.
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.SH RETURN VALUE
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\fBmu index\fR return 0 upon successful completion, and any other number
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greater than 0 signals an error.
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.SH BUGS
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Please report bugs if you find them:
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.BR https://github.com/djcb/mu/issues
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.SH AUTHOR
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Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
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.SH "SEE ALSO"
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.BR maildir(5)
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.BR mu(1)
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.BR mu-find(1)
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.BR mu-cfind(1)
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