Find and replace code in HTML files (no jQuery)

[Dyclerace]

I have 3000+ html files in a folder. Is it possible to use any scripting to find inside all html files, any image tag that has src="http://stackoverflow.com/questions/14453154/XXX_logo.png" and add text ending with " logo" to the alt attribute which already contains a value? I can't use jQuery. EG:BEFORE:\[code\]<div class="copyright"><div class="floatleft"><img src="http://stackoverflow.com/questions/14453154/support_files/organisation_logo.png" alt="The organisation" width="104" height="48" class="floatleft"/></div><div class="footer-statements"><div class="floatright"><img src="http://stackoverflow.com/questions/14453154/support_files/partner_logo.png" alt="Organisation partner name" width="273" height="48" /></div><div class="copyright-lines"><!-- metadata:content-rights--></div></div>\[/code\]AFTER (desired result):\[code\]<div class="copyright"><div class="floatleft"><img src="http://stackoverflow.com/questions/14453154/support_files/organisation_logo.png" alt="The organisation logo" width="104" height="48" class="floatleft"/></div><div class="footer-statements"><div class="floatright"><img src="http://stackoverflow.com/questions/14453154/support_files/partner_logo.png" alt="Organisation partner name logo" width="273" height="48" /></div><div class="copyright-lines"><!-- metadata:content-rights--></div></div>\[/code\]