Daan Kortenbach

Redirects users to the login page if the user is not logged in. After login the user gets redirected to the original entry page. For advanced users a filter is provided to override the redirect.
The principle behind this plugin is to redirect all users – from every post, page, archive, etc. – to the login page (usually wp-login.php). Except for the override filter it does nothing else.
<h4>Overriding the redirect</h4>
<ul>
<li>Note: This plugin may not be for you, a membership plugin might be a better fit. Chris Lema writes excellent reviews of +30 membership plugins here: http://chrislema.com/category/memberships-plugins/</li>
</ul>
If you do have a need for this plugin and you want to exclude specific views under specific conditions, a filter is provided to override the redirect.
To override the redirect the filter must return a boolean value of <code>true</code>. WordPress core provides many conditional tags that either return <code>true</code> or <code>false</code> or you can write your own conditionals.
Take a look at the Conditional Tags page on The WordPress Codex for some inspiration. 
https://codex.wordpress.org/Conditional_Tags
Usage: 
Copy/paste/edit an example to the functions.php of your theme or create a new file in wp-content/mu-plugins/ if you do not wish to edit your theme.
Note: Be carefull not to use multiple filters at the same time as that may cause unexpected results. Instead use multiple conditions in one filter.
<ul>
<li>
Override if the front page is either posts or a page:
add_filter( ‘rtl_override_redirect’, ‘is_front_page’ );
</li>
<li>
Override if the post is ‘hello-world’:
add_filter( ‘rtl_override_redirect’, function() { 
 return is_single( ‘hello-world’ ); 
 });
</li>
<li>
Override if the page is ‘sample-page’:
add_filter( ‘rtl_override_redirect’, function() { 
 return is_page( ‘sample-page’ ); 
 });
</li>
<li>
Override if the page ID is 42, the slug is ‘sample-page’ or the title is ‘About Me’:
add_filter( ‘rtl_override_redirect’, function() { 
 return is_page( array( 42, ‘sample-page’, ‘About Me’ ) ); 
 });
</li>
<li>
Override if the page ID is 42 or a post is ‘hello-world’:
add_filter( ‘rtl_override_redirect’, function() { 
 if ( is_page( 42 ) || is_single( ‘hello-world’ ) ) { 
 return true; 
 } 
 });
</li>
</ul>

Redirect to login if not logged in

Redirects users to the login page if the visitor is not logged in.

Michele Butcher-Jones

A plugin which redirects subscriber level users back to the homepage after they’ve logged in.
This plugin is maintained by Christopher Ross, http://thisismyurl.com or you can find him on Twitter at http://twitter.com/thisismyurl/
<h3>Updates</h3>
Updates to the plugin will be posted here, to http://thisismyurl.com/
<h3>Donations</h3>
If you would like to donate to help support future development of this tool, please visit http://thisismyurl.com/

WordPress Login Redirect

A plugin which redirects subscriber level users back to the homepage after they've logged in.

Redirect to login if not logged in vs WordPress Login Redirect