How to increase simultaneous connections in mysql

Some time we may get error like

Warning: mysql_connect(): Too many connections in /home/user/public_html/db.php on line 1
Unable to connect to database server!

We can increase simultaneous connections in mysql upto the maximum limit.
Open /etc/my.cnf file in your terminal window

Add the below line if not exist max_connections=100
else update the number of connections

Then restart your mysql
/etc/init.d/mysqld restart