#!/usr/bin/awk -f BEGIN { flag_debut = 1; lastminute = 0; cumul = 0.0; compte = 0; } # iterate over all the input lines { if (flag_debut) { debut = $1 flag_debut = 0 } minutes = int(($1-debut) / 60); if (minutes == lastminute) { val = ($2 + $3 + $4 + $5); cumul += val; compte += 4; } else { val = cumul /compte; print minutes, val; lastminute = minutes; cumul = 0; compte = 0; } }