Server Stop, Start, Restart (Apache, SSH, MySql)

Server Stop, Start, Restart (Apache, SSH, MySql)

Apache:

Q. I’m using CentOS / RHEL / Fedora Linux server and I’d like to restart my httpd server after making some changes to httpd.conf file. How do I restart httpd?

A. You can use service command to restart httpd. Another option is use /etc/init.d/httpd service script.

Login as root user and type the following commands:

Task: Start httpd server:

# service httpd start

Task: Restart httpd server:

# service httpd restart

Task: Stop httpd server:

# service httpd stop
Please note that restart option is a shorthand way of stopping and then starting the Apache HTTPd Server. You need to restart server whenever you make changes to httpd.conf file. It is also good idea to check configuration error before typing restart option:
# httpd -t
# httpd -t -D DUMP_VHOSTS
Sample output:

Syntax OK

Now restart httpd server:
# service httpd restart
Where,

• -t : Run syntax check for config files
• -t -D DUMP_VHOSTS : Run syntax check for config files and show parsed settings only for vhost.

/etc/init.d/httpd script

You can also use following command:
# /etc/init.d/httpd restart
# /etc/init.d/httpd start
# /etc/init.d/httpd stop

A note about Debian / Ubuntu Linux

Type the following command under Debian / Ubuntu Linux:
# /etc/init.d/apache2 restart
# /etc/init.d/apache2 stop
# /etc/init.d/apache2 start
You can also use service command under Debian / Ubuntu Linux:

# service apache2 restart
# service apache2 stop
# service apache2 start

SSH:

Q. How do I monitor my ssh server with monit? How do I restart ssh server if it does not respond or dead due to any issues under Linux?

A. You can easily monitor Linux server or service such as OpenSSH (SSHD daemon) using monit utility.

Monitor SSH and Auto Restart If Died

Open your /etc/monitrc or /etc/monit/monitrc file:
# vi /etc/monit/monitrc
Append following code:
check process sshd with pidfile /var/run/sshd.pid
start program "/etc/init.d/ssh start"
stop program "/etc/init.d/ssh stop"
if failed port 22 protocol ssh then restart
if 5 restarts within 5 cycles then timeout
Save and close the file. Make sure you set /var/run/sshd.pid and /etc/init.d/ssh as per your Linux distribution. These values are valid for Debian / Ubuntu Linux. Restart monit to pickup the changes:

# /etc/init.d/monit restart

Mysql:

Each distribution comes with a shell script (read as service) to restart / stop / start MySQL server. First login as root user and open shell prompt (command prompt).

First login as root user. Now type the following command as per your Linux distro:

A) If you are using mysql on RedHat Linux (Fedora Core/Cent OS) then use following command:

* To start mysql server:

/etc/init.d/mysqld start

* To stop mysql server:

/etc/init.d/mysqld stop

* To restart mysql server

 /etc/init.d/mysqld restart

Tip: Redhat Linux also supports service command, which can be use to start, restart, stop any service:

# service mysqld start
# service mysqld stop
# service mysqld restart

(B) If you are using mysql on Debian / Ubuntu Linux then use following command:

* To start mysql server:

/etc/init.d/mysql start

* To stop mysql server:

/etc/init.d/mysql stop

* To restart mysql server

/etc/init.d/mysql restart