11.5. 各種 Services 的啟動方式

Contributed by Tom Rhodes.

Many users choose to install third party software on FreeBSD from the Ports Collection. In many of these situations it may be necessary to configure the software in a manner which will allow it to be started upon system initialization. Services, such as mail/postfix or www/apache13 are just two of the many software packages which may be started during system initialization. This section explains the procedures available for starting third party software.

In FreeBSD, most included services, such as cron(8), are started through the system start up scripts. These scripts may differ depending on FreeBSD or vendor version; however, the most important aspect to consider is that their start up configuration can be handled through simple startup scripts.

Before the advent of rc.d, applications would drop a simple start up script into the /usr/local/etc/rc.d directory which would be read by the system initialization scripts. These scripts would then be executed during the latter stages of system start up.

While many individuals have spent hours trying to merge the old configuration style into the new system, the fact remains that some third party utilities still require a script simply dropped into the aforementioned directory. The subtle differences in the scripts depend whether or not rc.d is being used. Prior to FreeBSD 5.1 the old configuration style is used and in almost all cases a new style script would do just fine.

While every script must meet some minimal requirements, most of the time these requirements are FreeBSD version agnostic. Each script must have a .sh extension appended to the end and every script must be executable by the system. The latter may be achieved by using the chmod command and setting the unique permissions of 755. There should also be, at minimal, an option to start the application and an option to stop the application.

The simplest start up script would probably look a little bit like this one:

#!/bin/sh
echo -n ' utility'

case "$1" in
start)
        /usr/local/bin/utility
        ;;
stop)
        kill -9 `cat /var/run/utility.pid`
        ;;
*)
        echo "Usage: `basename $0` {start|stop}" >&2
        exit 64
        ;;
esac

exit 0

This script provides for a stop and start option for the application hereto referred simply as utility.

Could be started manually with:

# /usr/local/etc/rc.d/utility.sh start

While not all third party software requires the line in rc.conf, almost every day a new port will be modified to accept this configuration. Check the final output of the installation for more information on a specific application. Some third party software will provide start up scripts which permit the application to be used with rc.d; although, this will be discussed in the next section.

11.5.1. Extended Application Configuration

Now that FreeBSD includes rc.d, configuration of application startup has become easier, and more featureful. Using the key words discussed in the rc.d section, applications may now be set to start after certain other services for example DNS; may permit extra flags to be passed through rc.conf in place of hard coded flags in the start up script, etc. A basic script may look similar to the following:

#!/bin/sh
#
# PROVIDE: utility
# REQUIRE: DAEMON
# KEYWORD: shutdown

. /etc/rc.subr

name=utility
rcvar=utility_pidfile

command="/usr/local/sbin/utility"

load_rc_config $name

#
# DO NOT CHANGE THESE DEFAULT VALUES HERE
# SET THEM IN THE /etc/rc.conf FILE
#
utility_enable=${utility_enable-"NO"}
pidfile=${utility_pidfile-"/var/run/utility.pid"}

run_rc_command "$1"

This script will ensure that the provided utility will be started after the daemon service. It also provides a method for setting and tracking the PID, or process ID file.

This application could then have the following line placed in /etc/rc.conf:

utility_enable="YES"

This new method also allows for easier manipulation of the command line arguments, inclusion of the default functions provided in /etc/rc.subr, compatibility with the rcorder(8) utility and provides for easier configuration via the rc.conf file.

11.5.2. 以 Services 來啟動各式 Services

Other services, such as POP3 server daemons, IMAP, etc. could be started using the inetd(8). This involves installing the service utility from the Ports Collection with a configuration line appended to the /etc/inetd.conf file, or uncommenting one of the current configuration lines. Working with inetd and its configuration is described in depth in the inetd section.

In some cases, it may be more plausible to use the cron(8) daemon to start system services. This approach has a number of advantages because cron runs these processes as the crontab's file owner. This allows regular users to start and maintain some applications.

The cron utility provides a unique feature, @reboot, which may be used in place of the time specification. This will cause the job to be run when cron(8) is started, normally during system initialization.

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