UNIX for Advanced & Expert Users

#! /bin/sh
echo "please enter a user name"
read user
if user=$user
    then
 do
User=`who |grep user1,user2,user3|cut -d " " -f1`
echo User ID = $User
fi
 done

#!/bin/sh
echo "please enter a user name"
read user
who -u | grep "^${user} " | awk '{print $1}'

#!/bin/sh
echo "please enter a user name"
read user
user_login_count=`who -u | grep "^${user} " | wc -l`
if [ ${user_login_count} -gt 0 ]
then
       echo "User ${user} is logged in ${user_login_count} times"
       # Show some evidence
       who -u | grep "^${user} " | awk '{print $1}'
else
       echo "User ${user} is not logged in"
fi

user_login_count=$(who -u | grep "^${user} " | wc -l)