Q:

Specific url to work with and without .php using .htaccess

I'm trying to configure a specific url to work with and without .php extension.
For example want to access the url below both ways:
example.com/manage.php

example.com/manage

Here's my current .htaccess:
<IfModule mod_rewrite.c>
        RewriteEngine On
        RewriteBase /

        # Removes index.php from ExpressionEngine URLs
        RewriteCond %{THE_REQUEST} ^GET.*index\.php [NC]
        RewriteCond %{REQUEST_URI} !/library/.* [NC]
        RewriteRule (.*?)index\.php/*(.*) /$1$2 [R=301,NE,L]

        # Directs all EE web requests through the site index file
        RewriteCond %{REQUEST_FILENAME} !-f
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteRule ^(.*)$ /index.php?/$1 [L,QSA]
        # RewriteRule ^(.*)$ /index.php/$1 [L]
</IfModule>

A:

You can insert a rewrite rule just below your redirect rule:
RewriteEngine On
RewriteBase /

# Removes index.php from ExpressionEngine URLs
RewriteCond %{THE_REQUEST} ^GET.*index\.php [NC]
RewriteCond %{REQUEST_URI} !/library/.* [NC]
RewriteRule (.*?)index\.php/*(.*) /$1$2 [R=301,NE,L]

# add .php extension to specific URIs
RewriteRule ^(manage)/?$ $1.php [L,NC]

# Directs all EE web requests through the site index file
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php?/$1 [L,QSA]

