https://www.pbainbridge.co.uk/2019/01/student-feedback-system-get-active.html

1) Get active spreadsheet user.gs

function getActiveUser(sheet) {

  // get active Tutor email address
  var user = Session.getActiveUser().getEmail();
  Logger.log('Active Tutor email is: ' + user);
  
  // get data from Tutors sheet to lookup name from email address
  var tutorsSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Tutors');
  var tutorsSheetData = tutorsSheet.getRange(2, 1, 2, 2).getValues();
  
  
  // lookup active Tutor email address for corresponding name in Tutors sheet
  var tutorName = ''; // create empty variable
  if (user == tutorsSheetData[0][0]) {
    Logger.log(user + ' matches ' + tutorsSheetData[0][0]);
    var tutorName = tutorsSheetData[0][1];
    Logger.log('Tutor name is therefore: ' + tutorName);
  }
  else if (user == tutorsSheetData[1][0]) {
    Logger.log(user + ' matches ' + tutorsSheetData[1][0]);
    var tutorName = tutorsSheetData[1][1];
    Logger.log('Tutor name is therefore: ' + tutorName);
  }
  

  // get Tutor 1 name from sheet, split just for name
  var tutor1Name = sheet.getRange(1, 3).getValue().split(': ');
  Logger.log('Tutor 1 name is: ' + tutor1Name[1]);
  
  // get Tutor 2 name from sheet, split just for name
  var tutor2Name = sheet.getRange(1, 7).getValue().split(': ');
  Logger.log('Tutor 2 name is: ' + tutor2Name[1]);
  
  // find out if user is Tutor 1 or Tutor 2
  if (tutorName == tutor1Name[1]) {
    Logger.log(tutorName + ' matches ' + tutor1Name[1]);
    var tutorName = 'You are 1';
  }
  else if (tutorName == tutor2Name[1]) {
    Logger.log(tutorName + ' matches ' + tutor2Name[1]);
    var tutorName = 'You are 2';
  }
  else {
    Logger.log('No one matches');
  }
  
  return tutorName;
  
}