Below is a ready-to-use script. Review and adapt variables to your environment.
#!/usr/bin/env bash cat >/etc/security/limits.d/99-hardening.conf <<'EOF' * soft nofile 65535 * hard nofile 65535 root soft nofile 65535 root hard nofile 65535 EOF echo "Configured /etc/security/limits.d/99-hardening.conf"