Why is my MacBook warm when the lid is closed (in sleep mode)?

When I woke up last night it was a little windy outside, so I decided to unplug my MacBook Pro because the power tends to flicker here. When I picked up the MacBook I noticed that it was very warm, even though the lid was closed and it was in sleep mode. This morning I decided to dig into the “Why is my MacBook hot even though the lid is closed and it’s in sleep mode” question.

Why we can easily distribute Erlang programs over multicores or networks

“In Erlang it’s OK to mutate state within an individual process but not for one process to tinker with the state of another process ... processes interact by one method, and one method only, by exchanging messages. Processes share no data with other processes. This is the reason why we can easily distribute Erlang programs over multicores or networks.”

Joe Armstrong, in the book Programming Erlang

MySQL show status: How to show open database connections



New, free Introduction to Unix and Linux tutorial

After having this on my "wish list" for many years, I finally took the time tonight to regenerate the pages for my "Free Introduction to Unix and Linux tutorial". The old format was just horrible, spread out among 285 small pages, and while this one still needs some work, it's about 1,000 times better than the old format, and comes in weighing only 13 large tutorial pages.

Some of the tutorial material is a little dated now, but these sections are still very relevant to today's Unix/Linux world:

ps man page

The contents of this page come from the CentOS Linux ps man page, i.e., the man page for the Linux ps command (also known as the help page for the ps command).

Mac Activity Monitor - Mac process and memory usage

The Mac OS X Activity Monitor is a cool utility. As shown in the following figure, the main screen shows all the processes running on your system, the user that owns the process, the percent of CPU it's using, the virtual memory it's using, and more. My most common thing here is to sort by memory or CPU use to get a general idea of what's going on.