netstat is old and is not shipped anymore with modern distributions: it has been superseded by ss.
In order to fix the XAMPP 'netstat: command not found' error shown on Linux while starting the XAMPP service, simply edit file /opt/lampp/share/xampp/xampplib and change line 22 from:
if netstat -an | egrep "[.:]$1 .*LISTEN" > /dev/null
to
if ss -an | egrep "LISTEN.*[.:]$1" > /dev/null