General-Purpose Mail Filter
Right after startup, when
mailfromd has done the
operations that require root privileges, it switches to the privileges
of the user it is configured to run as (see default user privileges) or
the one given in its configuration file (see user). During
this process it will drop all supplementary groups and switch to the
principal group of that user.
Such limited privileges of the daemon can cause difficulties if your
filter script needs to access some files (e.g.
databases) that are not accessible to that user and group. For
example, the following fragment using
if dbmap("/etc/mail/aliases.db", $f, 1) … fi
will normally fail, because /etc/mail/aliases.db is readable only to the root and members of the group ‘smmsp’.
In such situations you need to instruct
retain the privileges of one or several supplementary groups when
switching to the user privileges. This is done using
statement in the
mailfromd configuration file
(see group). In example above, you need to use the following
(The same effect can be achieved with --group command line option: mailfromd --group=smmsp).
To stop a running instance of
mailfromd use one of the
All three signals have the same effect: the program cancels handling any
pending requests, uninitializes the communication socket (if it is a
UNIX socket, the program unlinks it) and exits.
To restart the running
mailfromd instance, send it
SIGHUP. For restart to be possible, two conditions must be
mailfromd must be invoked with the full file name, and the
configuration file name must be full as well. If either of them is not
mailfromd displays a similar warning message:
warning: script file is given without full file name warning: restart (SIGHUP) will not work
warning: mailfromd started without full file name warning: restart (SIGHUP) will not work
The reaction of
SIGHUP in this case is
the same as on the three signals described previously, i.e. cleanup
and exit immediately.
The PID of the master instance of
kept on the pidfile, which is named mailfromd.pid and is
located in the program state directory. Assuming the default
location of the latter, the following command will stop the running
instance of the daemon:
kill -TERM `head -n1 /usr/local/var/mailfromd/mailfromd.pid`
The default pidfile location is shown in the output of
--show-defaults (see Databases), and can be changed at run time using
pidfile statement (see pidfile).
To facilitate the use of
mailfromd, it is shipped with a shell
script that can be used to launch it on system startup and shut it
down when the system goes down. The script, called
rc.mailfromd, is located in the directory /etc of the
distribution. It takes a single argument, specifying the action that
should be taken:
Start the program.
Shut down the program
Reload the program, by sending it
Shut down the program and start it again.
Display program status. It displays the PID of the master process and its command line, for example:
$ /etc/rc.d/rc.mailfromd status mailformd appears to be running at 26030 26030 /usr/local/sbin/mailfromd --group smmsp
If the second line is not displayed, this most probably mean that there is a ‘stale’ pidfile, i.e. the one left though the program is not running.
An empty rc.mailfromd status output means that
mailfromd is not running.
Check the script file syntax, report any errors found and exit. If file is given it is checked instead of the default one.
Parse the script file (or file, if it is given, extract the names of Sendmail macros it uses and generate corresponding export statements usable in the Sendmail configuration file. By default, mc statements are generated. If -c (--cf) is given, the statements for sendmail.cf are output. See the next chapter for the detailed description of this mode.
You can pass any additional arguments to
ARGS variable near line 22.
The script is not installed by default. You will have to copy it to the directory where your system start-up scripts reside and ensure it is called during the system startup and shut down. The exact instructions on how to do so depend on the operating system you use and are beyond the scope of this manual.
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