Ngnix 301 redirect - nginx

Question

I'm using nginx.
Nginx is not working properly routing the short address.
Sorry, I'm using google translate. My English bad.
Example;
location /a {
return 301 http://www.example.com/abcd;
}
Or
location /a {
rewrite ^(.*)$ http://www.example.com/abcd permanent;
}
Doesn't work.
Response: Too many redirects;
>>> http://www.example.com/a
> --------------------------------------------
> 301 Moved Permanently
> --------------------------------------------
Status: 301 Moved Permanently
Code: 301
Server: nginx
Date: Fri, 16 Oct 2015 23:46:00 GMT
Content-Type: text/html
Content-Length: 178
Connection: close
Location: http://www.example.com/abcd
>>> http://www.example.com/abcd
> --------------------------------------------
> 301 Moved Permanently
> --------------------------------------------
Status: 301 Moved Permanently
Code: 301
Server: nginx
Date: Fri, 16 Oct 2015 23:46:00 GMT
Content-Type: text/html
Content-Length: 178
Connection: close
Location: http://www.example.com/abcd
>>> http://www.example.com/abcd
> --------------------------------------------
> 301 Moved Permanently
> --------------------------------------------
Status: 301 Moved Permanently
Code: 301
Server: nginx
Date: Fri, 16 Oct 2015 23:46:01 GMT
Content-Type: text/html
Content-Length: 178
Connection: close
Location: http://www.example.com/abcd
>>> http://www.example.com/abcd
> --------------------------------------------
> 301 Moved Permanently
> --------------------------------------------
Status: 301 Moved Permanently
Code: 301
Server: nginx
Date: Fri, 16 Oct 2015 23:46:01 GMT
Content-Type: text/html
Content-Length: 178
Connection: close
Location: http://www.example.com/abcd
But long address successful;
location /what-can-i-do {
rewrite ^(.*)$ http://www.example.com/please-help-me permanent;
}
My /etc/nginx/sites-available/example.com configuration;
server {
server_name example.com www.example.com;
if ($http_host = example.com) {
return 301 http://www.example.com$request_uri;
}
listen 00.00.00.00:80;
root /home/example/public_html;
index index.html index.htm index.php;
access_log /var/log/virtualmin/example.com_access_log;
error_log /var/log/virtualmin/example.com_error_log;
fastcgi_param GATEWAY_INTERFACE CGI/1.1;
fastcgi_param SERVER_SOFTWARE nginx;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SCRIPT_FILENAME /home/example/public_html$fastcgi_script_name;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT /home/example/public_html;
fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name;
fastcgi_param HTTPS $https;
location /a {
return 301 http://www.example.com/abcd;
}
location /ajax {
add_header "Access-Control-Allow-Origin" "*";
try_files $uri $uri/ /index.php?$args;
}
set $no_cache "";
if ($request_method = POST)
{
set $no_cache 1;
}
if ($request_method !~ ^(GET|POST|HEAD)$ ) {
return 444;
}
server_tokens off;
server_name_in_redirect off;
location ~* .(ico|webp|css|js|ico|bmp|zip|woff)$
{
expires 30d;
add_header Pragma public;
add_header Cache-Control "public";
try_files $uri /index.html;
}
location ~* \.(?:jpg|jpeg|gif|png|ico|cur|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
expires 1M;
access_log off;
add_header Cache-Control "public";
}
location ~* \.(?:css|js)$ {
expires 1y;
access_log off;
add_header Cache-Control "public";
}
location / {
try_files $uri $uri/ #rewrites;
}
location #rewrites {
if (!-e $request_filename)
{
rewrite ^/(.*)$ /index.php/$1 last;
break;
}
}
location = /favicon.ico {
access_log off;
log_not_found off;
}
location ~ /\. {
access_log off;
log_not_found off;
deny all;
}
fastcgi_intercept_errors on;
location ~ \.php {
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass_header Set-Cookie;
fastcgi_pass_header Cookie;
fastcgi_ignore_headers Cache-Control Expires Set-Cookie;
fastcgi_param PATH_INFO $fastcgi_path_info;
fastcgi_param PATH_TRANSLATED $document_root$fastcgi_path_info;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT $document_root;
fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param SERVER_SOFTWARE nginx;
fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name;
fastcgi_index index.php;
fastcgi_pass unix:/var/run/php5-fpm.sock;
}
listen 00.00.00.00:00 default ssl;
ssl_certificate /home/example/ssl.cert;
ssl_certificate_key /home/example/ssl.key;
}

Answer 1

Anything that follows /a is sent to /abcd which matches the /a given the current options=> When /a is requested, redirect to /a => An infinate loops occurs.
location /a {
return 301 http://www.example.com/abcd;
}
Change it into location = /a { and it will behave differently.
tl;dr
A location block looks like this:
location optional_modifier location_match {
. . .
}
Here's a very informative page, quote about the optional_modifier:
(none): If no modifiers are present, the location is interpreted as a prefix match. This means that the location given will be matched against the beginning of the request URI to determine a match.
=: If an equal sign is used, this block will be considered a match if the request URI exactly matches the location given.
...
Hence, set it to = to make a direct match, or any of the other options available.