get slack notify when login to ubuntu server

ubuntu_ssh_login_slack_notify.sh

  #/bin/sh
  # #######################################
  # pam REF: https://askubuntu.com/a/448602   https://blog.stalkr.net/2010/11/login-notifications-pamexec-scripting.html
  # copy to /usr/local/bin, then +x
  # add "session optional pam_exec.so type=open_session seteuid log=/tmp/pam.log /usr/local/bin/login_slack_notify.sh" to /etc/pam.d/sshd
  # work on Ubuntu 14.04.5 / Centos 7.9
  # selinux refer https://unix.stackexchange.com/a/474063 https://bugzilla.redhat.com/show_bug.cgi?id=737906#c1

  #echo "User: $PAM_USER" >> /tmp/a.txt
  #echo "Ruser: $PAM_RUSER" >> /tmp/a.txt
  #echo "Rhost: $PAM_RHOST" >> /tmp/a.txt
  #echo "Service: $PAM_SERVICE" >> /tmp/a.txt
  #echo "TTY: $PAM_TTY" >> /tmp/a.txt
  #echo "Date: `date`" >> /tmp/a.txt
  #echo "Server: `uname -a`" >> /tmp/a.txt
  #echo >> /tmp/a.txt

  host=`hostname`
  now=$(date '+%Y-%m-%d %H:%M:%S %Z')
  ip=`hostname -I | cut -d " " -f 1`
  slack_url="YOUR_SLACK_API"
  content='{"text":"'"$PAM_USER"' from '"$PAM_RHOST"' on '"${host}-${ip}"' through '"${PAM_SERVICE}-${PAM_TTY}"' at '"$now"'"}'
  curl -X POST -H 'Content-type: application/json' -d "$content" $slack_url