\usepackage{lineno} ... \linenumbers
\newcommand*\patchAmsMathEnvironmentForLineno[1]{% \expandafter\let\csname old#1\expandafter\endcsname\csname #1\endcsname \expandafter\let\csname oldend#1\expandafter\endcsname\csname end#1\endcsname \renewenvironment{#1}% {\linenomath\csname old#1\endcsname}% {\csname oldend#1\endcsname\endlinenomath}}% \newcommand*\patchBothAmsMathEnvironmentsForLineno[1]{% \patchAmsMathEnvironmentForLineno{#1}% \patchAmsMathEnvironmentForLineno{#1*}}% \AtBeginDocument{% \patchBothAmsMathEnvironmentsForLineno{equation}% \patchBothAmsMathEnvironmentsForLineno{align}% \patchBothAmsMathEnvironmentsForLineno{flalign}% \patchBothAmsMathEnvironmentsForLineno{alignat}% \patchBothAmsMathEnvironmentsForLineno{gather}% \patchBothAmsMathEnvironmentsForLineno{multline}% }