Tutorials, write-ups, and ramblings on various tech-related things.
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UNIX Process Groups
Note: This was written for students in Purdue’s CS 252 course. Hopefully the information will be useful to others as well, but there may be some references that don’t make sense. Hello fellow CS 252 student! Process groups are quite an important part of how shells and terminals function, so I was a bit sad to find out that CS 252 neglects to cover them at all. I decided to learn about them on my own and implement them in my shell....
Profiling ZSH: How I made my shell start 90% faster
Over the years, my .zshrc has grown to include many tricks & tools I rely on daily. But it also meant that my shell took a fair amount of time to start up, around 1 second: 1 2 3 $ time zsh -i -c exit ... zsh -i -c exit 0.31s user 0.14s system 47% cpu 0.949 total One second may not sound like a lot, but it meant that every time I opened a new terminal tab, my shell prompt wouldn’t show up until after I started typing....
Start Docker containers on-demand with systemd socket activation
If you have a Docker container which is running all the time but is used infrequently, it may be a good idea to start the container only when a connection is received. This is particularly useful for resource-intensive servers. In my case, I use this for a Minecraft server, which can take several gigabytes of memory even when idle, so I want to keep it running as little as possible....
SRVUSD-BYOD Network Credentials
If you’re simply looking for a tutorial on how to connect your device to the network securely, go to the Tutorials section. Why this article? Android recently got an update which prevents you from connecting insecurely to WPA Enterprise networks. The IT staff for SRVUSD firmly insisted that it is now simply impossible to connect an Android phone to the SRVUSD-BYOD network. I didn’t believe them, so I brought my laptop to school, used Wireshark to dump the WPA handshake, and found the certificate information that is needed to connect securely....
Trick to shift lines in Vim
It’s easy to select lines in visual mode, delete them, then paste them a few lines lower. However, this won’t adjust the indentation to match surrounding code. Instead, add the following to your vimrc (or init.vim): 1 2 3 " Move visual selection vnoremap K :m '<-2<cr>gv=gv vnoremap J :m '>+1<cr>gv=gv Then select lines using visual mode (v or V) and press J or K to shift them down or up one line, respectively....