Is my redirect not removing final slash? - .htaccess

Question

I have a site that I don't think my htaccess is implementing 301 redirects properly, I think my problem may be at the application level but I would appreciate it if someone can confirm the following works as I expect it to.
Example redirect: http://www.siteic.com/a/b/c/ should go to http://www.siteic.com/a/b/c - however the below doesn't do that. NOTICE the trailing slash is removed.
Options +FollowSymLinks
RewriteEngine on
ErrorDocument 404 /
RewriteCond %{HTTP_HOST} ^siteic\.com
RewriteRule ^(.*)$ http://www.siteic.com/$1 [R=permanent,L]
RewriteCond {REQUEST_URI} ^/first/$
RewriteRule ^(.*)$ http://www.siteic.com [R=permanent,L]
RewriteCond {REQUEST_URI} ^/first$
RewriteRule ^(.*)$ http://www.siteic.com [R=permanent,L]
RewriteRule ^first/([a-z,\_%,A-Z,\_%-,0-9,\-]*)$ otherst.php?page=$1
RewriteRule ^first/([a-z,\_%,A-Z,\_%-,0-9,\-]*)/([a-z,\_%,A-Z,\_%-,0-9,\-]*)$ otherst.php?page=$1&page2=$2

Answer 1

I would suspect you first rule to be always true, therefore the subsequent rules are never used.
You should use that instead:
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www.your_domain.com$
RewriteRule ^(.*)$ http://www.your_domain.com/$1 [R=301]
Your second rule makes sure all uri with the string '/first/' redirect to the homepage.
Your third rule does exactly the same with the string '/first' so in fact you could remove your second rule, or your third one depending on your intended behaviour.
Your fourth rule will never match because uri with "first/" will have been redirected to homepage.
Your fifth rule should come before your fourth rule because rule 4 will be more often true than rule 5.
As to your request: how to remove the trailing slash, i would do this:
- first make sure the path points to a non-existent directory
- if true, remove the slash
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)/$ /$1 [R=301,L]
So in the end i would do this:
RewriteEngine on
# force WWW in the url
RewriteCond %{HTTP_HOST} !^www.siteic.com$
RewriteRule ^(.*)$ http://www.siteic.com/$1 [R=301]
# remove trailing slash if the url points to a non-existing folder
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)/$ /$1 [R=301,L]
# redirects all url with /first to otherst.php
## with 2 GET vars
RewriteRule ^first/([a-z,\_%,A-Z,\_%-,0-9,\-]*)/([a-z,\_%,A-Z,\_%-,0-9,\-]*)$
otherst.php?page=$1&page2=$2
## with 1 GET var
RewriteRule ^first/([a-z,\_%,A-Z,\_%-,0-9,\-]*)$ otherst.php?page=$1