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ubuntu add permission to folder

sudo chmod -R 777 /var/DirectoryName

set all permissions to folder in ubuntu

sudo chmod -R a+rwx path/directory

give permission to file ubuntu

sudo chmod 777 /path

how to change permissions for the whole folder in ubuntu

sudo chmod -R 777 DirectoryName

give permission to user in ubuntu

sudo chown -R testuser:testuser /var/www/test/public_html

giving permission to folder in ubuntu

chmod -R a+rwx path

how assign permission to a folder and all contents in ubuntu|linux

only change the no(like 777,775 etc) according to your need 
current scenior i am giving full permission to file/sub-directories
chmod -R 777 your_directory_name

assign permission to files and folder ubuntu separate

To change all the directories to 755 (drwxr-xr-x):
find /opt/lampp/htdocs -type d -exec chmod 755 {} ;

To change all the files to 644 (-rw-r--r--):
find /opt/lampp/htdocs -type f -exec chmod 644 {} ;