從 2002 年起,FreeBSD 整合了 NetBSD 的 rc.d
機制來作為系統服務啟動機制。
可以到 /etc/rc.d
目錄下去看,很多檔案都是基本服務,可以用 start
, stop
及 restart
作為使用時的選項。
舉個例子,可以用下列指令來重新啟動 sshd(8):
#
/etc/rc.d/sshd restart
其他服務也是類似作法。當然,
服務通常只要在 rc.conf(5) 內有指定的話,都會在開機時就自動啟動。舉例來說,若要開機時啟動 NAT(Network Address
Translation) daemon 的話,只要在 /etc/rc.conf
內加上下列這行即可:
若原本寫的是 natd_enable="NO"
那麼只要把 NO
改為
YES
就好了。rc scripts 會在下次重開機時,自動載入相關(有相依)的服務,以下我們會講到這部分。
Since the rc.d
system is primarily
intended to start/stop services at system startup/shutdown time,
the standard start
,
stop
and restart
options will only
perform their action if the appropriate
/etc/rc.conf
variables are set. For
instance the above sshd restart
command will
only work if sshd_enable
is set to
YES
in /etc/rc.conf
. To
start
, stop
or
restart
a service regardless of the settings in
/etc/rc.conf
, the commands should be
prefixed with “force”. For instance to restart
sshd
regardless of the current
/etc/rc.conf
setting, execute the following
command:
#
/etc/rc.d/sshd forcerestart
It is easy to check if a service is enabled in
/etc/rc.conf
by running the appropriate
rc.d
script with the option
rcvar
. Thus, an administrator can check that
sshd
is in fact enabled in
/etc/rc.conf
by running:
#
/etc/rc.d/sshd rcvar
# sshd
$sshd_enable=YESThe second line (# sshd
) is the output
from the sshd
command, not a root
console.
若要檢查服務是否有在運作,可以用 status
選項來查詢。比如:若要確認
sshd
是否真的有啟動的話,那麼打:
#
/etc/rc.d/sshd status
sshd is running as pid 433.In some cases it is also possible to reload
a service.
This will attempt to send a signal to an individual service, forcing the
service to reload its configuration files. In most cases this
means sending the service a SIGHUP
signal. Support for this feature is not included for every service.
The rc.d
system is not only used for network services, it also
contributes to most of the system initialization. For
instance, consider the bgfsck
file. When
this script is executed, it will print out the following
message:
Therefore this file is used for background file system checks, which are done only during system initialization.
Many system services depend on other services to function
properly. For example, NIS and other RPC-based services may
fail to start until after the rpcbind
(portmapper) service has started. To resolve this issue,
information about dependencies and other meta-data is included
in the comments at the top of each startup script. The
rcorder(8) program is then used to parse these comments
during system initialization to determine the order in which
system services should be invoked to satisfy the dependencies.
The following words may be included at the top of each startup
file:
PROVIDE
: Specifies the services this file provides.
REQUIRE
: Lists services which are required for this
service. This file will run after
the specified services.
BEFORE
: Lists services which depend on this service.
This file will run before
the specified services.
By using this method, an administrator can easily control system services without the hassle of “runlevels” like some other UNIX® operating systems.
Additional information about the
rc.d
system can be found in the rc(8)
and rc.subr(8) manual pages.
本文及其他文件,可由此下載: ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/。
若有 FreeBSD 方面疑問,請先閱讀
FreeBSD 相關文件,如不能解決的話,再洽詢
<questions@FreeBSD.org>。
關於本文件的問題,請洽詢
<doc@FreeBSD.org>。