1, case statement execution process:

Case statements can well replace the multi branch structure in if statements. When using case branch statements, there are several noteworthy features as follows:

• The first mock exam must be the word "in", and each mode must end with the right bracket). The case must end with the right bracket.

• Double semicolon ";;" indicates the end of the command sequence;

• ***

• The last ")" indicates the default mode, in which the wildcard is used;

2. Write a system service script with case syntax:

The following sleep command is used to pause the specified time. You can change it to the control command sequence of the corresponding background service according to your own needs.

[root@centos01 ~]# vim myprog
#!/bin/bash
case "$1" in
start)
        echo -n "Starting sleep service..."
if
         sleep 7200 &
then
        echo "OK"
fi
;;
stop)
        echo -n "Stopping sellp Services..."
        pkill "sleep" &> /dev/null
        echo "OK"
;;
status)
if 
        pgrep "sleep" &> /dev/null
then
        echo "sleep The service has started."
else
        echo "sleep The service has stopped."
fi
;;
restart)
$0 stop
$0 start
;;
\*)
echo "usage:$0 { start | stop | status | restart }"
esac

#Save exit, test script:

[root@centos01 ~]# chmod 744 myprog
[root@centos01 ~]# ./myprog.sh stop
//Stopping sellp service... OK
[root@centos01 ~]# ./myprog status
sleep The service has started.
[root@centos01 ~]# ./myprog start
//Starting the sleep service... OK

3. Writing Nginx service control script with case statement

[root@centos01 ~]# vim  nginx.sh            <! -- create script -- >
#!/bin/bash
#chkconfig: 35 90 30
#description:nginx server
PROG="/usr/local/nginx/sbin/nginx"
PIDF="/usr/local/nginx/logs/nginx.pid"
case "$1" in
start)
$PROG
        echo "Starting Nginx Service!!!"
;;
stop)
kill -s QUIT $(cat $PIDF)
        echo "Stopping Nginx Service!!!"
;;
restart)
        echo "Restarting Nginx Service!!!"
$0 stop
$0 start
;;
reload)
kill -s HUP $(cat $PIDF)
;;
*)
echo "Usage:$0 (start|stop|restart|reload)"
exit 1
esac
exit 0
<!--Save exit, add execution permission-->
[root@centos01 ~]# chmod +x  nginx.sh         <! -- script add execution permission -- >
[root@centos01 ~]# / nginx.sh  Start <! -- start nginx -- >
//Starting Nginx service!!!
[root@centos01 ~]# ! net <! -- see if it starts -- >
netstat -anptu |grep nginx 
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      29899/nginx: master
[root@centos01 ~]# / nginx.sh  Restart <! -- restart nginx -- >
//Restarting Nginx service!!!
//Stopping Nginx service!!!
//Starting Nginx service!!!
[root@centos01 ~]# ! net <! -- check whether Nginx is running -- >
netstat -anptu |grep nginx
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      29918/nginx: master
[root@centos01 ~]# / nginx.sh  Stop <! -- stop nginx -- >
//Stopping Nginx service!!!
[root@centos01 ~]# ! net <! -- verify that Nginx stops -- >
netstat -anptu |grep nginx

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