Useful CentOS commands

1. CentOS command to check version

cat /etc/centos-release

2. install php 7

https://webtatic.com/packages/php70/

3. install apache on centos7

http://www.liquidweb.com/kb/how-to-install-apache-on-centos-7/

4. install phpMyAdmin

http://www.liberiangeek.net/2014/09/install-phpmyadmin-centos-7-lamp-support/

5. install LAMP

https://www.digitalocean.com/community/tutorials/how-to-install-linux-apache-mysql-php-lamp-stack-on-centos-7

6. install firewall in centos 7

systemctl list-units --type=service


Install if not available:
  yum install firewalld


You can enable firewalld by typing:
systemctl enable firewalld
sudo systemctl enable firewalld


You can start firewalld by typing:
systemctl start firewalld
sudo systemctl start firewalld


Have a look to check its status by typing:
systemctl status firewalld

http://serverfault.com/questions/683666/how-to-enable-firewall-on-centos-7

advanced configuration:
https://www.howtoforge.com/tutorial/install-and-configure-csf-config-server-firewall-on-centos-7/

7. modify the config file with the bellow code for phpMyAdmin:

vi /etc/httpd/conf.d/phpMyAdmin.conf

Alias /phpMyAdmin /usr/share/phpMyAdmin

Alias /phpmyadmin /usr/share/phpMyAdmin



<Directory /usr/share/phpMyAdmin/>

   AddDefaultCharset UTF-8



<IfModule mod_authz_core.c>

        # Apache 2.4

        <RequireAny>

                Require ip 192.168.1.196

                Require ip ::1

                Require all granted

        </RequireAny>

</IfModule>

<IfModule !mod_authz_core.c>

        # Apache 2.2

        Order Deny,Allow

        Deny from All

        Allow from 192.168.1.196

        Allow from ::1

</IfModule>



</Directory>



<Directory /usr/share/phpMyAdmin/setup/>

   <IfModule mod_authz_core.c>

     # Apache 2.4

     <RequireAny>

       Require ip 192.168.1.196

     </RequireAny>

   </IfModule>

   <IfModule !mod_authz_core.c>

     # Apache 2.2

     Order Deny,Allow

     Deny from All

     Allow from 192.168.1.196

   </IfModule>

</Directory>

Restart Apache:

# service httpd restart




8. change and configure the root directory of apache / httpd and set SElINUX=disabled:

http://stackoverflow.com/questions/17442370/you-dont-have-permission-to-access-on-this-server



https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/3/html/Reference_Guide/s1-apache-config.html







9. Tar and Untar files:

Extract / Uncompress:

tar -xvf file.tar

tar -xzvf file.tar.gz

tar -xjvf file.tar.bz2

tar -xvf file.tar etc/resolv.conf
tar -xzvf file.tar.gz etc/resolv.conf
tar -xjvf file.tar.bz2 etc/resolv.conf

source: http://www.cyberciti.biz/faq/tar-extract-linux/

Compress / Tar files:

tar -cvf file.tar etc/resolv.conf 

source: https://www.centos.org/docs/2/rhl-gsg-en-7.2/s1-zip-tar.html

10. install and configure APC in CentOS:

http://anandarajpandey.com/2014/07/15/how-to-install-apc-in-centos-for-php-better-performance-opcode/

11. install DRUSH 8 in CentOS:

http://docs.drush.org/en/master/install/

12. Change root password and Create new user in CentOS:

How to change password via SSH in Linux/Centos? First, you need login SSH to your Linux server, then use command passwd to change password. below example is change root password for a Centos:

-bash-3.2# su - root  - you don't need to do this if you already login ssh as root
[root @ ComfortVPS.com ~]# passwd root - usage: passwd <accountName> , passwd root means change password for accountname root
Changing password for user root.
New UNIX password:   (You should type your new password here)
Retype new UNIX password:   (You should retype your new password again)
passwd: all authentication tokens updated successfully.

Done, you have successfully changed your password!

copy from: http://www.comfortvps.com/VPS/How-change-password-SSH-Linux-Centos.html

Create a new user and granting root privilege:

adduser demo

passwd demo

gpasswd -a demo wheel

https://www.digitalocean.com/community/tutorials/how-to-install-linux-nginx-mysql-php-lemp-stack-on-centos-7

13. List All Users In The System:

$ cat /etc/passwd

Linux Command to List Users:

$ awk -F':' '{ print $1}' /etc/passwd

http://www.cyberciti.biz/faq/linux-list-users-command/

14. Starting and Stopping vsftpd:

/sbin/service vsftpd start

/sbin/service vsftpd restart

https://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-ftp-vsftpd-start.html

15. Change hostname of Linuxh machine:

Verify current hostname:

# hostname

Verify current dns domain name:

# dnsdomainname

Update the hostname:

# hostname NewHostMachineName

16. Create self-signed SSL certificate and implement

Create self-sign-in certificate ( https://www.digitalocean.com/community/tutorials/how-to-create-a-ssl-certificate-on-nginx-for-centos-6 ) in certificate folder (i.e.: /etc/pki/tls/certs/):

# openssl x509 -inform der -in ServerStaging.cer -out ServerStaging.key

 PS: it is recommended to not to use passphrase.

Update the webserver configuration file (i.e.: /etc/nginx/conf.d/default.conf):

# HTTPS server

server {
    listen       443;
    ServerStaging_name Server.Staging.com;

 add_header Strict-Transport-Security "max-age=31536000"; 
     ssl_certificate      /etc/ssl/certs/ServerStaging.crt;
     ssl_certificate_key  /etc/ssl/certs/ServerStaging.key;
     ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
  
    ... ... ... ... ... ....
    ... ... ... ... ... ....
    ... ... ... ... ... ....
}

17. Implement CA authorized SSL certificate

a. Copy the CA generated DER ServerStaging.CER certificate along with ServerStaging.KEY file at the certificate folder (i.e. /etc/pki/tls/certs): 

b. Used the following command to convert the DER .CER file to .PEM:

# openssl x509 -inform der -in ServerStaging.cer -out ServerStaging.pem

c. Replaced the CRT file with the PEM file in nGinx configuration file (i.e.: /etc/nginx/conf.d/default.conf). 

# HTTPS server

server {
    listen       443;
    ServerStaging_name Server.Staging.com;

 add_header Strict-Transport-Security "max-age=31536000"; 
 ssl on;
     ssl_certificate      /etc/ssl/certs/ServerStaging.pem;
     ssl_certificate_key  /etc/ssl/certs/ServerStaging.key;
     ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
  
    ... ... ... ... ... ....
    ... ... ... ... ... ....
    ... ... ... ... ... ....
}

d. Restart nGinx server (service nginx restart).

18. Force the search index to be rebuilt.

drush search-reindex

https://drushcommands.com/drush-8x/search/search-reindex/