# To best share with multiple users who should be able to write in /var/www,
# it should be assigned a common group. For example the default group for web content on Ubuntu
# and Debian is www-data. Make sure all the users who need access to /var/www are in this group.
sudo usermod -a -G www-data <some_user>
#Then set the correct permissions on /var/www.
sudo chgrp -R www-data /var/www
sudo chmod -R g+w /var/www
#Additionally, you should make the directory and all directories below it "set GID", so that all new files and directories created under /var/www are owned by the www-data group
sudo find /var/www -type d -exec chmod 2775 {} \;
#Find all files in /var/www and add read and write permission for owner and group:
sudo find /var/www -type f -exec chmod ug+rw {} \;

# To best share with multiple users who should be able to write in /var/www,
# it should be assigned a common group. For example the default group for web content on Ubuntu
# and Debian is www-data. Make sure all the users who need access to /var/www are in this group.
sudo usermod -a -G www-data <some_user>
#Then set the correct permissions on /var/www.
sudo chgrp -R www-data /var/www
sudo chmod -R g+w /var/www
#Additionally, you should make the directory and all directories below it "set GID", so that all new files and directories created under /var/www are owned by the www-data group
sudo find /var/www -type d -exec chmod 2775 {} \;
#Find all files in /var/www and add read and write permission for owner and group:
sudo find /var/www -type f -exec chmod ug+rw{} \;

Giving user access to /var/www folder

Bash