# lohedges/latuxit

A command-line clone of the excellent macOS program LaTeXiT.
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# LaTuXiT

Released under the GPL.

latuxit is a a command-line Linux clone of the excellent macOS program LaTeXiT. It provides a simple means of creating cropped LaTeX typeset equations in both PDF and PostScript format.

The program is a simple Bash script that requires no dependencies outside of the standard Tex Live core (other than Ghostscript for additional PostScript support). The script replicates two of LaTeXiT's key features: an equation library, and a reverse lookup feature to allow editing of existing equations. latuxit works by hashing each equation string and building a library. Metadata written as comments in the output PDF and PostScript images allows latuxit to match an image to an equation in the library. latuxit has full RGB color support and also accepts any of the 68 standard colors known to dvips. Equations can be processed using several of the standard amsmath equation environments, and using custom LaTeX pre- and post-amble files. Due to its command-line nature, latuxit provides a handy way of processing many equations from a batch script.

## Installation

After cloning the repository cd to the latuxit directory and run:

make setup
make install

Note that a user workspace directory is created at ~/.latuxit. This is where the latuxit configuration files and user equation library are stored. The ability to specify a custom path for the workspace directory will be added in a future version.

latuxit can be completely removed from your system as follows:

make uninstall
make clean

By default latuxit is installed to /usr/local so you may need admin privileges for the final make install step above. To install to a different location:

make setup
make PREFIX=PATH install

And to uninstall from a custom path:

make PREFIX=PATH uninstall
make clean

## Usage

latuxit can be run in a variety of different ways using equation input from the command-line, an editor, or from stdin. Several different use cases are illustrated below.

• Equation passed using the command-line option or typed in an editor.
latuxit [options]
• Equation passed via stdin. (three examples)
echo 'equation' | latuxit [options]
cat [FILE] | latuxit [options]
latuxit < [FILE] [options]
• Existing image edited using reverse lookup feature. (two examples)
latuxit [IMAGE]
latuxit [IMAGE] [options]

## Options

latuxit supports the following short- and long-form command-line options. Invoking latuxit when no equation has been passed using the command-line option or via stdin will open the editor defined by the LATUXIT_EDITOR environment variable. The user can then type an equation and latuxit will proceed as normal once the file has been saved and closed.

-e EQUATION, --equation EQUATION

EQUATION in LaTeX markup. No \$ symbols are needed. The EQUATION should be surrounded by single quotation marks, i.e. 'EQUATION', to ensure that it is parsed correctly (strong quoting). When the equation starts with a minus sign make sure the character is enclosed in curly braces, i.e. '{-}...' , so that it isn't mistaken as an identifier for a command-line argument. Alternatively, simply insert a blank space at the start of the equation. This will be ignored by LaTeX when the equation is typset. If no EQUATION is passed on the command-line or from stdin then latuxit will open the EQUATION editor defined by the LATUXIT_EDITOR environment variable. If pdflatex fails to process an EQUATION then the user will be given the opportunity to edit it again in order to correct any mistakes.

-c COLOR, --color COLOR

Where COLOR is one of the 68 standard colors defined in ~/.latuxit/latuxit.colors, or, alternatively, a COLOR in {R,G,B} format, where R,G,B=[0-1.0], or [0-255]. RGB colors should be surrounded by double quotation marks, i.e. '{R,G,B}', to ensure they are parsed correctly. Also make sure that there aren't any blank spaces on either side of any of the RGB values.

-o FILE_PREFIX, --output FILE_PREFIX

FILE_PREFIX is a prefix used for all output images, e.g FILE_PREFIX.pdf. The default is latuxit.

-d, --displaymath

Sets the equation environment to displaymath. This is the default environment. When setting an environment from the command-line the final option will take precedence. The command-line environment also takes precedence when processing an image in hash mode, or when reprocessing and existing latuxit image.

-a, --align

Sets the equation environment to align.

-g, --gather

Sets the equation environment to gather.

-l, --list

Lists all equations in the library along with their hash.

-s EQUATION, --search EQUATION

Searches the equation library for all partial matches of EQUATION. The matches are output along with the corresponding hash.

-m HASH, --md5 HASH

Run latuxit in "hash" mode. The HASH string is matched against equations in the library. It should be long enough to ensure a unique match. Once a match is found, latuxit will open the equation for editing with LATUXIT_EDITOR. Hashes are generated using the md5sum algorithm. A single letter prefix is added to specify the equation environment that was used to process the equation, e.g. d for displaymath.

-b, --batch

Run latuxit in "batch" mode. In batch mode latuxit will no longer ask the user to edit any failed equations. This is useful when processing a large number of equations using a batch script, e.g. when the user doesn't want to edit many potentially incorrect equations by hand, or deal with memory issues by opening many instances of the LATUXIT_EDITOR. Any failed equations will be reported to stdout along with the [FAILED] prefix.

-p, --purge

Purge the equation library.

-pre PREAMBLE, --preamble PREAMBLE

Load a custom LaTeX preamble file. The PREAMBLE should be an appropriately formatted tex file.

-post POSTAMBLE, --postamble POSTAMBLE

Load a custom LaTeX postamble file. The POSTAMBLE should be an appropriately formatted tex file.

-h, --help

Get help (loads the man page).

## Reverse lookup feature

Running latuxit on an image that was previously created with latuxit will search the file for metadata and open the corresponding equation from the library in the editor defined by the LATUXIT_EDITOR environment variable. This allows the user to modify an existing latuxit image. The image and equation are overwritten unless a different FILE_PREFIX is specified.

## Environment variables

latuxit's behavior is affected by the following environment variables. These can be sourced from ~/.latuxitrc or ~/.latuxit/latuxitrc.

LATUXIT_EDITOR

This variable specifies the editor to be used for typing equations. The default option is vim.

LATUXIT_COLOR

The COLOR of the equation. The default is Black, but the command-line option -c will take precedence.

LATUXIT_LIBRARY_SIZE

The size of the latuxit equation library. The default is 1000.

LATUXIT_POSTSCRIPT

Whether to also save a PostScript copy of the output PDF. The default is true.

LATUXIT_PURGE_CONFIRMATION

Whether to ask for confirmation before purging the equation library. The default is true.

LATUXIT_PREAMBLE

The default LaTeX preamble, ~/.latuxit/preamble.tex.

LATUXIT_POSTAMBLE

The default LaTeX postamble, ~/.latuxit/postamble.tex.

## Example workflow

### Basic usage

Suppose we want a nice red image of the canonical partition function. Here's a short example of a possible LaTuXiT workflow.

latuxit -e 'Z=\sum_s e^{\beta E_s}' -c 'Red'

There should now be two files in the working directory: latuxit.pdf, and latuxuit.ps. Let's open latuxit.pdf and see what it looks like

Whoops, it looks like we missed a minus sign, and how about we make the equation green instead. The following command will extract equation metadata from latuxit.pdf and open the equation in an editor where it can be corrected. Easy!

latuxit latuxit.pdf -c '{102,255,0}'

Let's check the modified image. Snazzy.

### Searching the equation library

Suppose you want to edit an equation but you've lost the image file. You can kind of remember the syntax, but it's long and complicated so you don't really fancy attempting to type it out again. What do you do then?

Thankfully latuxit offers a solution. As a starting point you can run latuxit in "search" mode.

latuxit -s 'sin'

\sin 2\theta = 2\sin \theta \cos \theta
The output shows a list of matching hashes from the library and the corresponding equations. (Note that you should try to match against the first line of any multiline equation.) Say the first match is the equation that we want. To reprocess it we can simply run latuxit in hash mode. The hash string that is passed as a command-line argument should be long enough to ensure a unique match. latuxit will abort if multiple matches are found. The equation will be opened in an editor so that it can be modified prior to processing.
latuxit -m dabad