Mu

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Mu is a multi-purpose tool shipped with Mailutils. It can be used for various mail- and database-related tasks, as well as an auxiliary tool for compiling and linking programs with Mailutils.

Syntax

Mu is a command line tool. Its invocation syntax is:

mu [options] command [args]

where options are options that affect the behavior of mu as a whole, command instructs it what it is to do and args are any arguments the command needs in order to be executed.

The commands are:

2047

Decodes or encodes email message headers.

acl

Tests Mailutils access control lists.

cflags

Shows compiler options needed to compile with Mailutils.

dbm

Invokes a DBM management tool.

filter

Applies a chain of filters to the input.

help

Displays a terse help summary.

imap

Invokes an IMAP4 client shell (in development).

info

Displays information about Mailutils compile-time configuration.

ldflags

Constructs a ld(1) command line for linking a program with Mailutils.

logger

Logs information using Mailutils log facility.

pop

Invokes a POP3 client shell.

query

Queries configuration values.

wicket

Scans wickets for matching URLs

help

The mu help command lists all available options and command names along with short descriptions of what each of them does. It is similar to the mu --help option.

A command name can be supplied as an argument to help, in which case it will display a help page for that particular command, e.g.:

 mu help ldflags

will output help for the ldflags command. It is synonymous to the --help option used with that particular command, e.g.: mu ldflags --help.

info

The mu info command displays information about Mailutils compile-time configuration. In normal form its output lists a single configuration flag per line, e.g.:

 $ mu info
 VERSION=2.99.93
 SYSCONFDIR=/etc
 MAILSPOOLDIR=/var/mail/
 SCHEME=mbox
 LOG_FACILITY=mail
 IPV6
 USE_LIBPAM
 HAVE_LIBLTDL
 WITH_GDBM
 WITH_GNUTLS
 WITH_GSASL
 ...

A configuration flag can consist either of a single word, indicating that a particular capability has been enabled at compile time, or of a keyword/value pair delimited by an equal sign, which indicates a particular value used by default for that feature. For example, IPV6 means that Mailutils was compiled with support for IPv6, whereas SYSCONFDIR=/etc means that the default place for configuration files is in /etc directory.

Such short output is convenient for using mu info in scripts to decide whether it is possible to use a given feature. To assist human users, the --verbose (-v) option is provided. It prints a short description next to each flag:

 $ mu info --verbose
 VERSION=2.99.93           - Version of this package
 SYSCONFDIR=/etc           - System configuration directory
 MAILSPOOLDIR=/var/mail/   - Default mail spool directory
 SCHEME=mbox               - Default mailbox type
 LOG_FACILITY=mail         - Default syslog facility
 IPV6                      - IPv6 support
 USE_LIBPAM                - PAM support
 HAVE_LIBLTDL              - a portable `dlopen' wrapper library
 WITH_GDBM                 - GNU DBM
 WITH_GNUTLS               - TLS support using GNU TLS
 WITH_GSASL                - SASL support using GNU SASL
 ...

cflags

The mu cflags command shows compiler options needed to compile a C source with Mailutils. It is intended for use in configuration scripts and Makefiles, e.g.:

 CFLAGS=-g -O2 `mu cflags`

ldflags

The mu ldflag command is a counterpart of cflags used for linking. It constructs a ld(1) command line for linking a program with Mailutils.

When used without arguments, it outputs ld arguments which would link only with the core Mailutils library libmailutils:

 $ mu ldflags
 -L/usr/local/lib -lmailutils 

This command accepts a number of keywords which allow to select a particular subset of Mailutils libraries to link with. In particular, the argument all instructs it to link in all available libraries:

 $ mu ldflags all
 -L/usr/local/lib -lmu_mbox -lmu_mh -lmu_maildir -lmu_imap -lmu_pop \
 -lmu_mailer -lmu_compat -lmailutils -lmu_auth -lgsasl -lgnutls -lgcrypt \
 -lldap -lgnuradius -lpam -ldl 

Other available keywords are:

mbox

Link in the UNIX mbox format support.

mh

Link in the MH format support.

maildir

Link in the Maildir format support.

imap

Link in the IMAP protocol support.

pop

Link in the POP protocol support.

nntp

Link in the NNTP protocol support.

mailer

Enable support for mailers.

sieve

Link in the support for Sieve mail filtering language.

dbm

Link in the support for DBM databases (libmu_dbm library).

compat

Provide a compatibility layer for Mailutils 2.x.

auth

Link in the Mailutils authentication library.

guile

Provide Guile language bindings.

python

Provide Python language bindings.

cfg

Link in the Mailutils configuration library.

argp

Link in the library for command line parsing.

query

The mu query command queries values from Mailutils configuration files. It takes one or more configuration paths as its arguments. On output, it displays the values it found, each value on a separate line. If the requested value is a block statement it is displayed in full. For example, if main configuration file contained:

  logging {
    syslog yes;
    facility mail;
  };

Then:

 $ mu query .logging.syslog
 syslog yes;
 $ mu query .logging.syslog .logging.facility
 syslog yes;
 facility mail;
 $ mu query .logging
 logging {
   syslog yes;
   facility mail;
 };

Several command line options allow to modify output format. The --value option instructs the command to output only values:

 $ mu query --value .logging.syslog
 yes

The --path option instructs it to print full path names for each value:

 $ mu query --path .logging.syslog
 logging.syslog: yes

The --program option instructs mu to behave as if it was called under another program name. For example, the following command:

 $ mu query --program=pop3d .server.transcript

will return the value of the server.transcript statement for pop3d utility.

By default, mu query operates on the main configuration file. Another configuration file can be supplied using the --file (-f) option:

 $ mu query --file /usr/local/etc/file.conf .pidfile

2047

The mu 2047 command is a filter for decoding or encoding email message headers formatted in accordance with RFC 2047. By default, it operates in encode mode and assumes the iso-8859-1 encoding. If arguments are supplied in the command line, they are treated as the text to operate upon. Otherwise the command acts as a UNIX filter, reading lines from the standard input and printing results on the standard output:

For examle:

 $ mu 2047 'Keld Jørn Simonsen <keld@dkuug.dk>'
 =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld@dkuug.dk>

The decode mode can be requested via the --decode (-d) option:

 $ mu 2047 --decode '=?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld@dkuug.dk>'
 Keld Jørn Simonsen <keld@dkuug.dk>

The --charset (-c) option changes the default character set. It is meaningful both in decode and in encode modes. In decode mode it instructs the utility to convert the output to the given character set. In encode mode it indicates the encoding of the input data, which will be reflected in the resulting string:

 $ mu 2047 --charset=utf-8 'Keld Jørn Simonsen <keld@dkuug.dk>'
 =?utf-8?Q?Keld J=C3=B8rn Simonsen <keld@dkuug.dk>?=

The --encoding (-E) option can be used in encode mode to change the output encoding. Valid arguments for this option are: quoted-printable (the default) or base64.

The --newline (-n) option prints an additional newline character after each line of output.

filter

Applies a chain of filters to the input.

acl

Tests Mailutils access control lists;

wicket

Scans wickets for matching URLs

dbm

The mu dbm tool manages DBM files using libmu_dbm. The invocation syntax is:

 mu dbm mode [options] file [keys]

where mode selects the operation mode, options modify the tool behavior and file specifies the DBM file to operate upon. Some modes allow for optional keys to be specified.

The file argument can be either a DBM file name or a Database URL.

Create a Database

The --create (-c) mode specifier instructs the tool to create a new database:

 mu dbm --create file.db

If the argument file already exists, it will be truncated prior to adding new records to it.

The data to populate the database with are read from the standard input. Each input line must consist of two fields separated by any amount of whitespace. The first field is treated as a key and the second one as the corresponding value.

The usual way to read data from a file is, of course, by redirecting the file to the standard input as in:

 mu dbm --create file.db < input.txt

There is also a special option for that purpose: --file (-f). Thus, the following command is equivalent to the one above:

 mu dbm --create --file input.txt file.db 

The --file option has the advantage that it allows, in conjunction with another options, for copying input file metadata (owner UID, GID and file mode) to the created database. For example, the following command ensures that the created database file will have the same metadata as the input file:

 mu dbm --create --file input.txt --copy-permissions file.db

The --copy-permissions (-P) option is one that does the job.

There are also other ways to control mode and ownership of the created database, which are described below.

Add Records to a Database

The --add (-a) mode adds records to a database. Records are read from the standard input and must be formatted as described above:

 mu dbm --add file.db

If the argument file does not exist, it will be created.

Adding a record with a key which is already present in the database produces an error. To replace existing records, use the --replace (-t) mode instead.

The same options that affect the behavior of --create apply to --add and --replace as well, e.g.:

 mu dbm --replace --file input.txt --copy-permissions file.db

Delete Records

To delete records, use the --delete (-d) mode. It reads a list of keys to delete to be specified as arguments in the command line:

 mu dbm --delete file.db foo bar

The command above will delete from file.db records with keys foo and bar.

It is not an error to attempt to delete a key that does not exist in the database, although such use will produce a warning message.

By default, keys are matched literally. It is also possible to use various pattern matching techniques, depending on the option specified.

The --glob (-G) option instructs the tool to use UNIX globbing pattern matching. For example, the command below will delete all keys starting with foo and ending with a decimal digit:

 mu dbm --delete file.db 'foo*[0-9]'

(note the quoting necessary to prevent shell from interpreting the metacharacters itself).

Another option, --regex (-R) instructs mu to treat keys as extended regular expressions:

 mu dbm --delete --regex file.db 'foo.*[0-9]{1,3}'

Both options are affected by the --ignore-case (-i) option, which turns on case-insensitive matching.

Using pattern matching to delete records can be a risky operation as selecting a wrong pattern will lead to removing wrong records. It is recommended to first use the list mode described below to verify that the patterns match the right keys.

List the Database

The --list (-l) mode lists the content of the database:

 mu dbm --list file.db

By default, entire content is listed on the standard output. Each output line represents a single record, with key and value parts separated by a single TAB character. This output format is suitable for use as input to the --create mode. Among other uses, this provides for an easy way to convert databases between various formats supported by Mailutils. For example the example below converts the database file file.db to the GDBM database new.db:

 mu dbm --list file.db | mu dbm --create gdbm://new.db

If supplied more than one command line argument, this mode treat the rest of arguments after the database file name as the keys to look for and lists only records with these keys:

 $ mu dbm --list file.db foo bar
 foo 1
 bar 56

The --glob and --regex options instruct the tool to use UNIX globbing or extended regular expression matching, correspondingly. These are described in detail above.

logger

Logs information using Mailutils log facility.

pop

Invokes a POP3 client shell.

imap

Invokes an IMAP4 client shell (in development).