2.4.1 Controlling Side by Side Format

The ‘-y’ or ‘--side-by-side’ option selects side by side format. Because side by side output lines contain two input lines, the output is wider than usual: normally 130 print columns, which can fit onto a traditional printer line. You can set the width of the output with the ‘-W columns’ or ‘--width=columns’ option. The output is split into two halves of equal width, separated by a small gutter to mark differences; the right half is aligned to a tab stop so that tabs line up. Input lines that are too long to fit in half of an output line are truncated for output.

The ‘--left-column’ option prints only the left column of two common lines. The ‘--suppress-common-lines’ option suppresses common lines entirely.