LATEX

How to Highlight Changes Between Two Versions of LaTeX Files

When working with LaTeX documents, it’s often necessary to compare two versions of a file to identify changes. This guide will walk you through the process of highlighting differences between two LaTeX files using latexdiff.

Prerequisites

Before proceeding, ensure you have the following tools installed:

  • LaTeX Distribution: Install a LaTeX distribution like TeX Live (for Linux/Windows) or MacTeX (for macOS).
  • Diff Tools: Install a diff tool such as:
    • latexdiff (recommended for LaTeX-specific comparisons).

Using latexdiff

latexdiff is a Perl script specifically designed to compare two LaTeX files and produce a new LaTeX file with highlighted changes.

Step 1: Install latexdiff

If you’re using a LaTeX distribution like TeX Live or MacTeX, latexdiff is likely already installed. Check via:

latexdiff --version

If it’s not installed, you can install it via:

sudo apt-get install latexdiff  # For Debian/Ubuntu
brew install latexdiff          # For macOS (using Homebrew)

If brew is not installed on your macOS, install via:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Step 2: Compare Two LaTeX Files

Run the following command to compare old.tex and new.tex:

latexdiff old.tex new.tex > diff.tex

This will generate a new file diff.tex with the following highlights:

  • Additions: Marked in blue with an underline.
  • Deletions: Marked in red with a strikethrough.

Step 3: Compile the Output

Compile the diff.tex file using your LaTeX editor or command-line tool:

pdflatex diff.tex

This will produce a PDF where changes are visually highlighted.

Customization: You can customize the output using additional options:

Use --type=CFONT to highlight changes using colored text instead of underlines and strikethroughs:

latexdiff --type=CFONT old.tex new.tex > diff.tex

Use --flatten to expands \input and \include commands for comparison:

latexdiff --flatten old.tex new.tex > diff.tex

To color what is added and not show what has been deleted, use the following options:

latexdiff --append-textcmd="textcolor{blue}" --exclude-textcmd="st" old.tex new.tex > diff.tex

To exclude differences in changing the image size, use the following option:

latexdiff --graphics-markup=0 old.tex new.tex > diff.tex

Example:

latexdiff --type=CFONT --append-textcmd="textcolor{blue}" --exclude-textcmd="st" --graphics-markup=0 old.tex new.tex > diff.tex

For more details, see: Marking up differences between latex files with latexdiff