Redirect /about to /about.php in .htaccess - .htaccess

Question

First of all, I know there are plenty of similar questions about this around, but
None of them seem to work for me
None of them actually address exactly what I want
What I want is, as the title suggests, to redirect URLs without the .php extension to the actual .php file - changing the URL if possible (which I presume is just handled by [R=301]). The latest thing I tried was this:
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(.+)$ $1.php [R=301]
That doesn't work. I can still cant access /about.php with /about. (.htaccess rules themselves are working fine though)
I understand RegEx fine, but htaccess rules just mess with my head =[
So what should I do?
Now I know what you're thinking
One of you will say this: "Why do you want to do this? Just get rid of extensions completely and access your pages via /about or /about/ with a trailing slash."
I'd like to do that, it looks quite good. Problem is SEO - from which I assume my page ranks will get annihilated because all of a sudden they're on different URLs. So before you suggest that, suggest how I'd keep my page ranks first.
What I'm actually doing is essentially URL shortening for a poster - it's a lot easier for people to remember mywebsite.com/about than mywebsite.com/about.php.

Answer 1

Enable mod_rewrite and .htaccess through httpd.conf and then put this code in your .htaccess under DOCUMENT_ROOT directory:
Options +FollowSymLinks -MultiViews
# Turn mod_rewrite on
RewriteEngine On
RewriteBase /
## hide .php extension
# To externally redirect /dir/foo.php to /dir/foo
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)\.php [NC]
RewriteRule ^ %1 [R=302,L]
# To internally forward /dir/foo/ to /dir/foo.php
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{DOCUMENT_ROOT}/$1.php -f
RewriteRule ^(.*?)/?$ $1.php [L]
Please Make sure you have MultiViews options disabled using: Options -MultiViews
Beware of Apaches multiviews
Once you verify it is working fine, replace R=302 to R=301. Avoid using R=301 (Permanent Redirect) while testing your mod_rewrite rules.

Answer 2

Please make sure that there's mod_rewrite on your Apache HTTP Server and try this:
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([a-zA-Z0-9_-]+)$ /$1.php [R]
But clear your cache or use another browser first before checking the redirecting dynamic URLs, because you've been previously used the [R=301] flag! For more info. about that, please visit: https://stackoverflow.com/a/15999177/2007055
Could you try this one but it's quite the same as the previous code:
RewriteEngine on
RewriteRule ^([a-zA-Z0-9_-]+)$ http://%{HTTP_HOST}/$1.php
And when it works, try adding these two conditions above the rewrite rule:
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([a-zA-Z0-9_-]+)$ http://%{HTTP_HOST}/$1.php
And when any of these codes above does not work, I think there's a problem in your Apache HTTP Server.

Answer 3

That works for me.
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php [L,QSA]
You can chain it if you want e.g.
RewriteEngine On
# Remove trailing slashes.
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)/$ /$1 [R=permanent,QSA]
# Redirect to HTML
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^(.+)$ $1.html [L,QSA]
# Redirect to PHP
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php [L,QSA]
# Redirect to ASP
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.asp -f
RewriteRule ^(.+)$ $1.asp [L,QSA]