Joomla Installation Blank Page

php -m

list modules
No SimpleXML

sudo apt-get install php7.0-simplexml

php -m

Will show
SimpleXML

Restart apache2

Joomla should start

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Ubuntu find Duplicated Files

Try this

find -name "*.pdf" -printf "%10s\t%p\n" | sort --numeric | uniq --repeated --check-chars=10

or
Search similar filesize:

find -name "*" -printf "%sc %p\n" | sort --numeric | uniq --repeated --check-chars=10 | cut -d' ' -f1 | grep -v '0c' >a; for i in `cat a`; do echo $i; find -size $i; echo; done

to ignore the file type

for i in `cat a| uniq| sort -nr`; do echo $i; find -size $i | xargs -I{} echo \"{}\"| xargs md5sum 2>/dev/null; done

below code is the wrap up

find -name "*" -printf "%sc %p\n" |sort --numeric | uniq --repeated --check-chars=10 | cut -d' ' -f1 | grep -v '0c'> a
rm b.txt
for i in `cat a| uniq| sort -nr`; do echo $i; find -size $i| xargs -I{} echo \"{}\"| xargs md5sum >>b.txt 2>/dev/null; done
cat b.txt |sort --numeric | uniq --repeated --check-chars=10 > c.txt
cat c.txt | cut -d'*' -f1 >d
rm e
for i in `cat d`; do grep $i b.txt >> e;done

Ubuntu Install boot-repair

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

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Ubuntu Cannot Enable WiFi

sudo modprobe -r acer_wmi

Source:
askubuntu.com 

Update grub on a dual boot machine

sudo nano /etc/default/grub 

sudo update-grub

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Install Wordpress on Ubuntu

Installation

To install WordPress, run the following comand in the command prompt:

    sudo apt install wordpress

You should also install apache2 web server and mysql server. For installing apache2 web server, please refer to Installation sub-section in HTTPD - Apache2 Web Server section. For installing mysql server, please refer to Installation sub-section in MySQL section.

Configuration

For configuring your first WordPress application, configure an apache site. Open /etc/apache2/sites-available/wordpress.conf and write the following lines:

        Alias /blog /usr/share/wordpress
        
            Options FollowSymLinks
            AllowOverride Limit Options FileInfo
            DirectoryIndex index.php
            Order allow,deny
            Allow from all
        
        
            Options FollowSymLinks
            Order allow,deny
            Allow from all
        
           

Enable this new WordPress site

    sudo a2ensite wordpress

Once you configure the apache2 web server and make it ready for your WordPress application, you should restart it. You can run the following command to restart the apache2 web server:

sudo systemctl restart apache2.service

To facilitate multiple WordPress installations, the name of this configuration file is based on the Host header of the HTTP request. This means that you can have a configuration per VirtualHost by simply matching the hostname portion of this configuration with your Apache Virtual Host. e.g. /etc/wordpress/config-10.211.55.50.php, /etc/wordpress/config-hostalias1.php, etc. These instructions assume you can access Apache via the localhost hostname (perhaps by using an ssh tunnel) if not, replace /etc/wordpress/config-localhost.php with /etc/wordpress/config-NAME_OF_YOUR_VIRTUAL_HOST.php.

Once the configuration file is written, it is up to you to choose a convention for username and password to mysql for each WordPress database instance. This documentation shows only one, localhost, example.

Now configure WordPress to use a mysql database. Open /etc/wordpress/config-localhost.php file and write the following lines:

Now create this mysql database. Open a temporary file with mysql commands wordpress.sql and write the following lines:

CREATE DATABASE wordpress;
GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP,ALTER
ON wordpress.*
TO wordpress@localhost
IDENTIFIED BY 'yourpasswordhere';
FLUSH PRIVILEGES;

Execute these commands.

cat wordpress.sql | sudo mysql --defaults-extra-file=/etc/mysql/debian.cnf

Your new WordPress can now be configured by visiting http://localhost/blog/wp-admin/install.php. (Or http://NAME_OF_YOUR_VIRTUAL_HOST/blog/wp-admin/install.php if your server has no GUI and you are completing WordPress configuration via a web browser running on another computer.) Fill out the Site Title, username, password, and E-mail and click Install WordPress.

Note the generated password (if applicable) and click the login password. Your WordPress is now ready for use.

https://help.ubuntu.com/lts/serverguide/wordpress.html

Blank screen after entering password on login screen Ubuntu

Right click on your virtue machine -> setting-> hardware -> display and deselect the option "3D acceleration"

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