sudo tee >/dev/null

Need to redirect to a file from sudo? Use sudo tee >/dev/null:

$ sudo ls -l /root >/root/files.list
-bash: /root/files.list: Permission denied
$ sudo ls -l /root | sudo tee /root/files.list >/dev/null
$ sudo ls -l /root/files.list
-rw-r--r-- 1 root root 94 Oct 18 09:31 /root/files.list

Use stdbuf to tee without buffering

Do you want to tee the output of a command to a file, but see it in your terminal too, without buffering? The stdbuf command can do this for you:

$ sudo stdbuf --output=L tcpdump -i any -tttt -n 'udp port 5353' | tee -a tcpdump-mdns
tcpdump: data link type LINUX_SLL2
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
2023-06-15 11:55:16.637670 eth0 M   IP > 0 A (QM)? winnebago.local. (28)
2023-06-15 11:55:16.744660 eth0 M   IP > 0*- [0q] 1/0/0 (Cache flush) A (38)