Limit number of unix logins

cat .profile

#!/bin/sh
limit=3

session=`ps -ef | grep '\-sh' | grep $USER | grep -v grep`

number=`echo $session | wc -l`

if [ $number -ge $limit ]; then
echo "No more logins / Il n'y a plus de login. You are already logged as:
$session "

sleep 5
exit 0
fi

# to timeout after 15min of inactivity and forbid users to change the tmout:
echo "TMOUT=900
readonly TMOUT
export TMOUT" > /etc/profile.d/tmout.sh && chmox +x /etc/profile.d/tmout.sh