HTACCESS redirecting to wrong page - regex

Question

When user enters url http://localhost/systems/admin in address bar I need to redirect user to page http://localhost/systems/admin/login/
It works fine when enter /admin
It does not work properly when I enter /admin/ (note trailing slashes), it redirects me to some other page http://localhost/systems/user/login but I want it to redirect me to same page i.e. http://localhost/systems/admin/login/
Below is my entire .htaccess code
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /systems/
RewriteRule ^admin$ http://localhost/systems/admin/login/ [R=301,L]
RewriteCond $1 !^(index\.php|resources|robots\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L,QSA]
</IfModule>

Answer 1

With your .htaccess configuration you are redirecting only /admin to /admin/login/.
To support a possible trailing slash you should go for something like:
RewriteRule ^admin/?$ http://localhost/systems/admin/login/ [R=301,L]
Generally speaking I would stick to only one notation (either with or without the trailing slash) and add a rule that always corrects wrong notations (i.e. adding or removing the trailing slash). A rule to remove the trailing slash could be:
RewriteRule ^(.*)/$ /$1 [L,R=301]
With such a rule you can stick to your original rewrite rule. In this case, however, you should always take care of returning addresses without the trailing slash in order to avoid rewriting when not necessary:
RewriteRule ^admin$ http://localhost/systems/admin/login [R=301,L]