Strings manipulation and variables in bash script - bash

Question

I try to download something with wget using for loop in bash script:
When i'm not using variables everything work fine, when i assign it into variables i have 500 server error. This is strange for me, because this is only copy-paste.
What i'm trying to do is take number from loop i and paste it into body.
Here is my code:
#!/bin/bash
for i in {1..5}
do
STR="some_static_stuff_before"$i"some_static_suff_after"
echo $STR
wget -O ready/page$i.aspx --header="Host: www.something.com" --header="Pragma: no-cache" --header="Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8" --header="Accept-Language: en-en" --header="Accept-Encoding: gzip, deflate" --header="Content-Type: application/x-www-form-urlencoded" --header="Origin: http://something.com" --header="Connection: keep-alive" --header="User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_1) AppleWebKit/537.73.11 (KHTML, like Gecko) Version/7.0.1 Safari/537.73.11" --header="Referer: http://www.something.com/something.aspx" --header="Cookie: ASP.NET_SessionId=u5cmt0figi4bvs40a30gnwsa; __utma=20059042.38323768.1389369038.1389710153.1389780868.6; __utmb=20059042.2.10.1389780868; __utmc=20059042; __utmz=20059042.1389627823.2.2.utmcsr=something.com|utmccn=(referral)|utmcmd=referral|utmcct=/something.aspx" --post-data='"$STR"' http://something.com/something.aspx
done
And when i paste object directly to --post-data there is no problem with download content.
I've tried --post-data= "/"$STR/"" and --post-data='"$STR"' and still not working.

Answer 1

You single-quoted the variable reference (in addition to double-quoting it), which prevents substitution of the variable value.
Instead of
--post-data='"$STR"'
use
--post-data="$STR"