Nikola Janjušević
Published 2020-01-03

My auto-reload setup for writing LATEX documents in VIM

  1. (Update) January 17th 2021
    1. REALLY setting your default viewer
    2. Zathura options
  2. January 3rd 2020
    1. My (Old) Setup:
    2. Automatic Tab-Reload in Firefox using XDOTOOL:
    3. Listening for File-Changes with entr and My New Setup:
    4. Future Work and Remarks:

(Update) January 17th 2021

It's a new year, and I've been using a new workflow for writing my LATEX documents in Vim. One frustration I had with my previous set up (see below) was the complicated nature of having automatic reloading using Firefox as my PDF viewer. Also, sometimes I don't want to open such a power hungry app just to view a PDF. So I now use Zathura, a minimal PDF viewer with customizable keyboard shortcuts (e.x. Vim key-bindings for moving around) that can be continuously updated by the compiler latexmk,

$ latexmk -pdf -pvc report.tex

The -pvc option allows for continuous previewing, which compiles the tex file at each write. As you could guess, -pdf option compiles the file to report.pdf. With the continuous previewing, we want to keep latexmk command running. It's useful to keep it in a separate terminal (don't push it to the background) as it will show us any warnings and compilation errors. When these happen, we can acknowledge the error with Ctrl-D, which tells latexmk to try compile the next file write.

We can open the PDF file via the terminal with,

$ zathura report.pdf --fork

The fork option allows us to close terminal. Alternatively, we can set Zathura to our default PDF viewer in our ~/.bashrc via $ export READER=zathura.

REALLY setting your default viewer

However, not all programs look at your environment variables to open files. A more widely used option is with the xdg-open command, which your computer will call by default when opening a file. There have been written many versions of this command. I've found mimi, which seems to have most easily configurable xdg-open "mime-types". Replace your default xdg-open with the one in the mimi repository (or add xdg-open to another fold with greater precedence in your $PATH variable). You can then make Zathura, or any other program, you default PDF viewer with the line application/pdf: zathura in the mimi configuration file, ~/.config/mimi/mime.conf.

Zathura options

Zathura looks for a configuration file called ~/.config/zathura/zathurarc. I set some options like making zooming in and out easier and more:

map K zoom in
map J zoom out
map u scroll half-up
map d scroll half-down
map r reload
map R rotate
set selection-clipboard clipboard

Many many more options are available and can be found in the zathurarc man page.

January 3rd 2020

I'm so happy with my current LATEX workflow that I want to share it. It is actually quite a niche problem that it's solving because it's born out of using VIM as my editor (a command-line editor) and Firefox as my PDF viewer. I enjoy VIM as its keyboard shortcuts allow me to write without being slowed down by using a mouse. Firefox is my PDF viewer of choice because 1. I always have it open anyway, and 2. It has a clean UI with features I like such as a table of contents and printing.

My (Old) Setup:

Manually compiling my LATEX document to preview my work involves to following 7 lines of keyboard strokes. It may not seem like a lot but it quickly gets annoying.

:w                      # write file in VIM
Ctrl-Z                  # stop VIM and put to background
latexmk -pdf report.tex # compile to pdf
Alt-Tab                 # swtich to Firefox
Ctrl-R                  # reload tab
Alt-Tab                 # switch to Terminal
fg                      # bring VIM to foreground, continue with life

I knew there had to be a better way. My goal was to find a method of having my computer listen for file changes in my .tex file and automatically compile to PDF and reload the viewer.

Automatic Tab-Reload in Firefox using XDOTOOL:

Sadly Firefox doesn't currently support automatic reload of a tab based on local file change (I believe it used to have a plugin for this, however, it was removed due to security risks). A workaround for this is using xdotool - a command line X11 automation tool. For those of us on UNIX-based operating systems (I believe almost all of which use X11, or some variant which allows xdotool to work), this lets us interact with our windows from the command line. That means we can essentially automate our Ctrl-R and Alt-Tab key-strokes from before. After some skimming of the man page and stackoverflow I arrived at the following reload script that gets the job done.

My reload bash script:

CURRENT_WID=$(xdotool getactivewindow)                     
WID=$(xdotool search --name "report.pdf - Mozilla Firefox")
xdotool windowactivate --sync $WID                         
xdotool key F5                                             
xdotool windowactivate $CURRENT_WID

In the first two lines of the above script we get the names of the current window (our terminal emulator) and the Firefox PDF window. We then switch focus to the PDF window with windowactivate and use the --sync argument to ensure we only run the next line after we're confirmed to be focused on the window. We then use xdotool to hit the F5 key, equivalent to hitting Ctrl-R. Finally we return focus to the command line.

Running the script via ./reload will reload the current tab on the Firefox window that is viewing the file report.pdf. Change the filename used in the script to your own accordingly. Don't forget to add execute permissions to the script by running chmod +x reload. All we have left to do is figure out how to run this script whenever our tex file is written to.

Listening for File-Changes with entr and My New Setup:

We can then use the command line tool entr - run arbitrary commands when a file changes to continuously listen for any file changes to report.tex and run our reload script. The following line in bash does the trick:

$ ls report.tex | entr -ps 'latexmk -pdf report.tex; ./reload'

ls lists information about report.tex and is piped into entr which listens for changes. The -p option tells entr to wait until the first change is noticed. The -s option allows us to give some shell commands in single-quotes, where we've opted to compile our tex file to pdf with latexmk and then run our reload script. You can keep this command in another terminal window or run it in the background of your current one. I keep it running in the foreground of another TMUX pane to the side of my VIM pane so that I can see any error messages if they occur.

My new setup now consists of simply writing the above bash one-liner at the start of each editing session, opening my draft PDF in Firefox with firefox report.pdf, and then saving my work in VIM with :w whenever I want to update my preview. The compilation and PDF reload now happens automatically whenever I save my tex file!

Future Work and Remarks: