First 60 Seconds: Summary
In 60 seconds you can get a high level idea of system resource usage and running processes by running the following ten commands. Look for errors and saturation metrics, as they are both easy to interpret, and then resource utilization. Saturation is where a resource has more load than it can handle, and can be exposed either as the length of a request queue, or time spent waiting.
uptime dmesg | tail vmstat 1 mpstat -P ALL 1 pidstat 1 iostat -xz 1 free -m sar -n DEV 1 sar -n TCP,ETCP 1 top
All the Wget Commands You Should Know
11. Download all images from a website in a common folder
wget ‐‐directory-prefix=files/pictures ‐‐no-directories ‐‐recursive ‐‐no-clobber ‐‐accept jpg,gif,png,jpeg12. Download the PDF documents from a website through recursion but stay within specific domains.
wget ‐‐mirror ‐‐domains=abc.com,files.abc.com,docs.abc.com ‐‐accept=pdf http://abc.com/
Setting up WordPress behind Amazon Cloudfront
Many websites and places that talk about integrating Amazon Cloudfront with WordPress are simply talking about static assets. Using some caching plugin that rewrites the URLs in the page’s source to point at your Cloudfront distribution, and that’s about it. They don’t talk about how your server can be (as WP SuperCache puts it) Stephen Fry-proof. No one actually says anything about how to put YOUR ENTIRE WEBSITE behind Amazon Cloudfront (and by this, I mean pointing your www.* domain at Cloudfront and letting it take care of everything).
Gzip/mod_deflate not Working? Check your Proxy Server
After scratching my head for a while, I finally figured out the problem, hinted at by a comment on a question on Stack Overflow. Our work’s proxy server was blocking the ‘Accept-Encoding’ http header that is sent along with every file request; this prevented a gzipped transfer of any file, thus Yslow gave an F.
I set up a secure tunnel (using SSH) from my computer to the web server directly, and then reloaded the page in FireFox, and re-ran YSlow:
Much happier now. I’ve contacted our IT department to see if it’s possible to allow the proxy server to pass through the Accept-Encoding headers, but for now, I’ll know to watch out for false positives on the YSlow test, and check from multiple locations.