mu - a set of tools to deal with Maildirs and message files, in particular to index and search e-mail messages.

NAME  SYNOPSIS  DESCRIPTION  COLORS  ENCODING  DATABASE AND FILE  COMMON OPTIONS  -d, --debug  -q, --quiet  --log-stderr  --nocolor  -V, --version  -h, --help  EXIT CODE  no matches found (2)  database schema mismatch (11)  failed to acquire lock (19)  REPORTING BUGS  AUTHOR  COPYRIGHT  SEE ALSO 


mu - a set of tools to deal with Maildirs and message files, in particular to index and search e-mail messages.



For information about the commmon options, see COMMON OPTIONS.


mu is the general command shows help about the specific commands:

add: add specific messages to the database.

cfind: find contacts

extract: extract attachments and other MIME-parts

find: find messages in the database

help: get help for some command

index: (re)index the messages in a Maildir

info: show information about the mu database

init: initialize the mu database

mkdir: create a new Maildir

remove: remove specific messages from the database

server: start a server process (for mu4e-internal use)

view: view a specific message

Each of the commands have their own manpage mu−<command˜>.

mu is a set of tools for dealing with Maildirs and the e-mail messages in them.

mu’s main purpose is to enable searching of e-mail messages. It does so by periodically scanning a Maildir directory tree and analyzing the e-mail messages found (this is called ’indexing’). The results of this analysis are stored in a database, which can then be queried.

In addition to indexing and searching, mu also offers functionality for viewing messages, extracting attachments and creating maildirs, and searching and exporting contact information.

mu can be used from the command line or can be integrated with various e-mail clients.

This manpage gives a general overview of the available commands (index, find, etc.); each mu command has its own man-page as well.


Some mu commands support colorized output, and do so by default. If you don’t want colors, you can use −−nocolor.


mu’s output is in the current locale, with the exceptions of the output specifically meant for output to UTF8-encoded files. In practice, this means that the output of commands index, view, extract is always encoded according to the current locale.

The same is true for find and cfind, with some exceptions, where the output is always UTF-8, regardless of the locale:

For cfind the exception is −−format=bbdb. This is hard-coded to UTF-8, and as such specified in the output-file, so emacs/bbdb can handle it correctly without guessing.

For find the output is encoded according the locale for −−format=plain (the default), and UTF-8 for all other formats.


Commands mu index and find and cfind work with the database, while the other ones work on individual mail files. Hence, running view, mkdir and extract does not require the mu database.


-d, --debug

makes mu generate extra debug information, useful for debugging the program itself. By default, debug information goes to the log file, ˜/.cache/mu/mu.log. It can safely be deleted when mu is not running. When running with --debug option, the log file can grow rather quickly. See the note on logging below.

-q, --quiet

causes mu not to output informational messages and progress information to standard output, but only to the log file. Error messages will still be sent to standard error. Note that mu index is much faster with --quiet, so it is recommended you use this option when using mu from scripts etc.


causes mu to not output log messages to standard error, in addition to sending them to the log file.


do not use ANSI colors. The environment variable NO_COLOR can be used as an alternative to −−nocolor.

-V, --version

prints mu version and copyright information.

-h, --help

lists the various command line options.


This command returns 0 upon successful completion, or a non-zero exit code otherwise. Typical values are 2 (no matches found), 11 (database schema mismatch) and 12 (failed to acquire database lock).

no matches found (2)

Nothing matching found; try a different query

database schema mismatch (11)

You need to re-initialize mu, see mu-init(1)

failed to acquire lock (19)

Some other program has exclusive access to the mu (Xapian) database


Please report bugs at


Dirk-Jan C. Binnema <[email protected]>


This manpage is part of mu 1.10.8.

Copyright © 2022-2023 Dirk-Jan C. Binnema. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


mu−add(1), mu−cfind(1), mu−extract(1), mu−find(1), mu−help(1), mu−index(1), mu−info(1), mu−init(1), mu−mkdir(1), mu−remove(1), mu−server(1), mu−view(1), mu−query(7), mu−easy(1)

Updated 2024-01-29 - |