Appending to config files with `tee -a`

Question

I'm trying to wrap my head around the thinking behind doing say

echo "nameserver 10.42.0.1" | sudo tee -a /etc/resolv.conf

rather than

echo "nameserver 10.42.0.1" >> /etc/resolv.conf

as root (e.g., after su or sudo bash). Is it a minimize time as root thing or is there something else to it?

Answer 1

It's a common Linux idiom. The idea behind it is to run only the tee process as root instead of a shell. Since tee is very simple, it's much less likely to have bugs or respond to unexpected user input in a dangerous way, compared to e.g. bash.