--- name: "mu" section: "1" platform: "linux" package: "maildir-utils" version: "1.12.9-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/mu" --- # mu(1) a set of tools to deal with Maildirs and message files, in particular to index and search e-mail messages. ## NAME mu - a set of tools to deal with Maildirs and message files, in particular to index and search e-mail messages. ## SYNOPSIS **mu** \[*COMMON-OPTIONS*\] \[\[*COMMAND*\] \[*COMMAND-OPTIONS*\]\] For information about the common options, see **COMMON OPTIONS**. ## DESCRIPTION **mu** is the general command that 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-\**. **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. ## COLORS Some **mu** commands support colorized output, and do so by default when writing to a TTY (roughly, to a screen). When not writing to a TTY, for instance when redirection the output to a file or using a pipe, the default is to **not** show output. If you don no want colors, you can use **--nocolor**. If you want colors even when it is not the default, use **--nocolor=false**. ## ENCODING **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. ## DATABASE AND FILE The **index**, **find**, and **cfind** commands 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. ## LOGGING **mu** logs to the standard logging location, which is either the systemd journal, **syslog** or a log file (by default, *~/.cache/mu/mu.log*), depending on your \*system's setup; the first that appears to be working is used. When using a log file, 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. ## COMMON OPTIONS ### -d, --debug Makes **mu** generate extra debug information, useful for debugging the program itself. Debug information goes to the standard logging location; see [**mu**(1)](/mu/1.md). ### -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. ### --log-stderr Causes **mu** to not output log messages to standard error, in addition to sending them to the standard logging location. ### --nocolor 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. ## EXIT CODE This command returns 0 upon successful completion, or a non-zero exit code otherwise. - 0\. success - 2\. no matches found. Try a different query - 11\. database schema mismatch. You need to re-initialize **mu**, see [**mu-init**(1)](/mu-init/1.md) - 19\. failed to acquire lock. Some other program has exclusive access to the **mu** database - 99\. caught an exception ## REPORTING BUGS Please report bugs at *https://github.com/djcb/mu/issues*. ## AUTHOR Dirk-Jan C. Binnema \ ## COPYRIGHT This manpage is part of **mu** 1.12.9. Copyright © 2008-2025 Dirk-Jan C. Binnema. License GPLv3+: GNU GPL version 3 or later *https://gnu.org/licenses/gpl.html*. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. ## SEE ALSO [**mu-add**(1)](/mu-add/1.md), [**mu-cfind**(1)](/mu-cfind/1.md), [**mu-extract**(1)](/mu-extract/1.md), [**mu-find**(1)](/mu-find/1.md), [**mu-help**(1)](/mu-help/1.md), [**mu-index**(1)](/mu-index/1.md), [**mu-info**(1)](/mu-info/1.md), [**mu-init**(1)](/mu-init/1.md), [**mu-mkdir**(1)](/mu-mkdir/1.md), [**mu-remove**(1)](/mu-remove/1.md), [**mu-server**(1)](/mu-server/1.md), [**mu-view**(1)](/mu-view/1.md), [**mu-query**(7)](/mu-query/7.md), [**mu-easy**(1)](/mu-easy/1.md)