Man pages matching name ifdown in section 8:

ifdown.8.en	debian 10 / ifupdown
ifdown.8.en	debian 10 / ifupdown2
ifdown.8.en	debian 10 / netscript-2.4
ifdown.8.en	debian 11 / ifupdown
ifdown.8.en	debian 11 / ifupdown2
ifdown.8.en	debian 11 / netscript-2.4
ifdown.8.en	debian 12 / ifupdown
ifdown.8.en	debian 12 / ifupdown-ng
ifdown.8.en	debian 12 / ifupdown2
ifdown.8.en	debian 12 / netscript-2.4