Linux命令service - 系统服务管理(转)

用途说明

service命令用于对系统服务进行管理，比如启动（start）、停止（stop）、重启（restart）、查看状态（status）等。相关的命令还包括chkconfig、ntsysv等，chkconfig用于查看、设置服务的运行级别，ntsysv用于直观方便的设置各个服务是否自动启动。service命令本身是一个shell脚本，它在/etc/init.d/目录查找指定的服务脚本，然后调用该服务脚本来完成任务。

看看下面的手册页可能更加清楚的了解service的内幕：service运行指定服务（称之为System V初始脚本）时，把大部分环境变量去掉了，只保留LANG和TERM两个环境变量，并且把当前路径置为/，也就是说是在一个可以预测的非常干净的环境中运行服务脚本。这种脚本保存在/etc/init.d目录中，它至少要支持start和stop命令。

man service 写道

service(8) service(8)

NAME
service - run a System V init script

SYNOPSIS
service SCRIPT COMMAND [OPTIONS]

service --status-all

service --help | -h | --version

DESCRIPTION
service runs a System V init script in as predictable environment as possible, removing most environment vari-
ables and with current working directory set to /.

The SCRIPT parameter specifies a System V init script, located in /etc/init.d/SCRIPT. The supported values of
COMMAND depend on the invoked script, service passes COMMAND and OPTIONS it to the init script unmodified. All
scripts should support at least the start and stop commands. As a special case, if COMMAND is --full-restart,
the script is run twice, first with the stop command, then with the start command.

service --status-all runs all init scripts, in alphabetical order, with the status command.

FILES
/etc/init.d
The directory containing System V init scripts.

ENVIRONMENT
LANG, TERM
The only environment variables passed to the init scripts.

常用方式

格式：service <service>

打印指定服务<service>的命令行使用帮助。

格式：service <service> start

启动指定的系统服务<service>

格式：service <service> stop

停止指定的系统服务<service>

格式：service <service> restart

重新启动指定的系统服务<service>，即先停止（stop），然后再启动（start）。

格式：chkconfig --list

查看系统服务列表，以及每个服务的运行级别。

格式：chkconfig <service> on

设置指定服务<service>开机时自动启动。

格式：chkconfig <service> off

设置指定服务<service>开机时不自动启动。

格式：ntsysv

以全屏幕文本界面设置服务开机时是否自动启动。

使用示例

示例一网络重启

当修改了主机名、ip地址等信息时，经常需要把网络重启使之生效。

[root@node34 root]# service network
用法：/etc/init.d/network {start|stop|restart|reload|status}
[root@node34 root]# service network status
配置设备：
lo eth0
当前的活跃设备：
lo eth0
[root@node34 root]# service network restart
正在关闭接口 eth0：                                        [ 确定 ]
关闭环回接口：                                             [ 确定 ]
设置网络参数：                                             [ 确定 ]
弹出环回接口：                                             [ 确定 ]
弹出界面 eth0：                                            [ 确定 ]
[root@node34 root]#

示例二重启MySQL

[root@node34 root]# service mysql
mysql: unrecognized service
[root@node34 root]# service mysqld
用法：/etc/init.d/mysqld {start|stop|status|condrestart|restart}
[root@node34 root]# service mysqld status
mysqld (pid 1638) 正在运行...
[root@node34 root]# service mysqld restart
停止 MySQL： [ 确定 ]
启动 MySQL： [ 确定 ]
[root@node34 root]#

示例三 service脚本源码展示

[root@web ~]# cat /sbin/service
#!/bin/sh

. /etc/init.d/functions

VERSION="`basename $0` ver. 0.91"
USAGE="Usage: `basename $0` < option > | --status-all | \
[ service_name [ command | --full-restart ] ]"
SERVICE=
SERVICEDIR="/etc/init.d"
OPTIONS=

if [ $# -eq 0 ]; then
echo "${USAGE}" >&2
exit 1
fi

cd /
while [ $# -gt 0 ]; do
case "${1}" in
    --help | -h | --h* )
       echo "${USAGE}" >&2
       exit 0
       ;;
    --version | -V )
       echo "${VERSION}" >&2
       exit 0
       ;;
    *)
       if [ -z "${SERVICE}" -a $# -eq 1 -a "${1}" = "--status-all" ]; then
          cd ${SERVICEDIR}
          for SERVICE in * ; do
            case "${SERVICE}" in
              functions | halt | killall | single| linuxconf| kudzu)
                  ;;
              *)
                if ! is_ignored_file "${SERVICE}" \
                    && [ -x "${SERVICEDIR}/${SERVICE}" ]; then
                  env -i LANG="$LANG" PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" status
                fi
                ;;
            esac
          done
          exit 0
       elif [ $# -eq 2 -a "${2}" = "--full-restart" ]; then
          SERVICE="${1}"
          if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
            env -i LANG="$LANG" PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" stop
            env -i LANG="$LANG" PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" start
            exit $?
          fi
       elif [ -z "${SERVICE}" ]; then
         SERVICE="${1}"
       else
         OPTIONS="${OPTIONS} ${1}"
       fi
       shift
       ;;
   esac
done

if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
   env -i LANG="$LANG" PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" ${OPTIONS}
else
   echo $"${SERVICE}: unrecognized service" >&2
   exit 1
fi
[root@web ~]#

示例四 crond服务的源码

[root@web init.d]# cat /etc/init.d/crond
#! /bin/bash
#
# crond          Start/Stop the cron clock daemon.
#
# chkconfig: 2345 90 60
# description: cron is a standard UNIX program that runs user-specified \
#              programs at periodic scheduled times. vixie cron adds a \
#              number of features to the basic UNIX cron, including better \
#              security and more powerful configuration options.
# processname: crond
# config: /etc/crontab
# pidfile: /var/run/crond.pid

# Source function library.
. /etc/init.d/functions
. /etc/sysconfig/crond
t=${CRON_VALIDATE_MAILRCPTS:-UNSET}
[ "$t" != "UNSET" ] && export CRON_VALIDATE_MAILRCPTS="$t"

# See how we were called.

prog="crond"

start() {
        echo -n $"Starting $prog: "
        if [ -e /var/lock/subsys/crond ]; then
            if [ -e /var/run/crond.pid ] && [ -e /proc/`cat /var/run/crond.pid` ]; then
                echo -n $"cannot start crond: crond is already running.";
                failure $"cannot start crond: crond already running.";
                echo
                return 1
            fi
        fi
        daemon crond $CRONDARGS
        RETVAL=$?
        echo
        [ $RETVAL -eq 0 ] && touch /var/lock/subsys/crond;
        return $RETVAL
}

stop() {
        echo -n $"Stopping $prog: "
        if [ ! -e /var/lock/subsys/crond ]; then
            echo -n $"cannot stop crond: crond is not running."
            failure $"cannot stop crond: crond is not running."
            echo
            return 1;
        fi
        killproc crond
        RETVAL=$?
        echo
        [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/crond;
        return $RETVAL
}

rhstatus() {
status crond
}

restart() {
stop
start
}

reload() {
        echo -n $"Reloading cron daemon configuration: "
        killproc crond -HUP
        RETVAL=$?
        echo
        return $RETVAL
}

case "$1" in
start)
        start
        ;;
stop)
        stop
        ;;
restart)
        restart
        ;;
reload)
        reload
        ;;
status)
        rhstatus
        ;;
condrestart)
        [ -f /var/lock/subsys/crond ] && restart || :
        ;;
*)
        echo $"Usage: $0 {start|stop|status|reload|restart|condrestart}"
        exit 1
esac
[root@web init.d]#

问题思考