Code.RogerHub

Writing essays in VIM and Latex

Roger Chen — Fri, 27 Mar 2015 23:03:45 +0000

I’m only taking one humanities course this semester, so I don’t have that many essays to write. But for the few assignments in that course, I’m planning to use VIM and Latex to write my essays. I have Pages.app installed on my laptop, and I already use Google Docs for stuff, but I’m still more comfortable writing in VIM, even if I’m not writing code.

Smart quotes

Latex handles smart quotes like you’d expect it to. If there are single-quotes or double-quotes in the text section of your document, they’ll get turned into left and right quotes in the final PDF.

Spell checking

I just use VIM’s built-in spell-checking feature. Make sure you use it with MacVIm/GVIM, or else it looks terrible. Apparently there’s a way to bring up the correction suggestions list too, if you look for it.

Rich formatting

You can do bold and italics and lists in Latex. I like it even better than the WYSIWYG editors, since you can do line manipulation and fancy macro stuff in VIM too.

Instant feedback

You can mix inotify-tools and your Latex compiler to get you basically instant feedback. Every time you save the file, you can get it to re-compile your Latex and Preview.app will reload it. I’m just sharing my home folder through VirtualBox shared folders (configured in Vagrant), so I can work with files directly on the VM.

MongoDB power usage on laptop

Roger Chen — Fri, 27 Mar 2015 22:51:55 +0000

I’m setting up a Chef-based Ubuntu VM on my laptop, so I can get sandboxing and all the usual Ubuntu tools. Most things work on OS X too, but it’s a second-class citizen compared to poster child Ubuntu. I have Mongo and a few services set up there, for school stuff, and I noticed that Mongo regularly uses a significant amount of CPU time, even when it’s not handling any requests.

I attached strace to it with strace -f -p 1056, and here’s what I saw:

[pid 1118] select(12, [11], NULL, NULL, {0, 10000} 
[pid 1056] select(11, [9 10], NULL, NULL, {0, 10000} 
[pid 1118] <... select resumed> ) = 0 (Timeout)
[pid 1056] <... select resumed> ) = 0 (Timeout)
[pid 1118] select(12, [11], NULL, NULL, {0, 10000} 
[pid 1056] select(11, [9 10], NULL, NULL, {0, 10000} 
[pid 1112] <... nanosleep resumed> 0x7fd3895319a0) = 0
[pid 1112] nanosleep({0, 34000000}, 
[pid 1118] <... select resumed> ) = 0 (Timeout)
[pid 1056] <... select resumed> ) = 0 (Timeout)
[pid 1118] select(12, [11], NULL, NULL, {0, 10000} 
[pid 1056] select(11, [9 10], NULL, NULL, {0, 10000} 
[pid 1118] <... select resumed> ) = 0 (Timeout)
[pid 1056] <... select resumed> ) = 0 (Timeout)
[pid 1118] select(12, [11], NULL, NULL, {0, 10000} 
[pid 1056] select(11, [9 10], NULL, NULL, {0, 10000} 
[pid 1118] <... select resumed> ) = 0 (Timeout)
[pid 1056] <... select resumed> ) = 0 (Timeout)
[pid 1118] select(12, [11], NULL, NULL, {0, 10000} 
[pid 1056] select(11, [9 10], NULL, NULL, {0, 10000} 
[pid 1112] <... nanosleep resumed> 0x7fd3895319a0) = 0

I looked online for an explanation, and I found this bug about MongoDB power usage. Apparently, it uses select() as a way to do timekeeping for all the ways Mongo uses wall time. Somebody proposed that alternative methods be used instead, which don’t require this kind of tight looping, but it looks like the Mongo team is busy with other stuff right now and won’t consider the patch.

So I added a clause in my Chef config to disable the MongoDB service from starting automatically on boot. I needed to specify the Upstart service provider explicitly in the configuration, since the mongodb package installs both a SysV script and Upstart manifest.

Comma mode for vim

Roger Chen — Sun, 05 Oct 2014 09:45:48 +0000

Most keyboards have a Control and Meta key. Macs also have the Command key. Even with all the combinations of Control and Meta and Command with the letters and numbers, it’s sometimes hard to have enough space for keyboard shortcuts that don’t conflict and override each other. This is especially important in vim, where keyboard shortcuts are everything. Most of the good ones are taken already.

My keybindings

I adapted an idea from tinymode.vim and created another key modifier: the comma. Here are some of the keybindings I’ve set:

,v creates a vertical split
,t opens a new tab
,1 toggles line wrapping
,2 opens NERDTree
,0 enables spellcheck and textwidth
,q quits the current buffer
,b opens CtrlP in buffer mode
,c opens the cd prompt
,f opens the filetype prompt
,U toggles line numbers

The comma works just like Control or Meta. You can hold it down and press multiple keyboard shortcuts. For example, multiple q’s can be chained to close multiple buffers in succession. Or t and v can be chained to create a new 2-pane tab.

Configuration

These six lines form the core of comma mode:

nmap , :set timeoutlen=86400000ldr
vmap , :set timeoutlen=86400000ldr
nn