Which shell configuration files are read for the shell started with "sudo -i"?

Question

According to man sudo sudo -i starts a login shell and should in my understanding read/source ~/.profile, i.e. /root/profile or [non-root user home/.profile and /etc/profile. Adding aliases, e.g. alias ll='ls -la' to both files doesn't make the alias available in the shell started by sudo -i. If I run bash in the shell stared by sudo -i aliases are available.

I already figured out to put aliases in /etc/profile.d/00-aliases.sh in https://askubuntu.com/questions/810730/how-to-share-bash-aliases-between-non-root-user-bash-and-shell-opened-by-sudo. Here I just want to know why the expected behaviour doesn't occur.

I reported this as a sudo bug on launchpad.net, but now I'm not sure whether this might be a tricky aspect of expected behaviour. The way man sudo describes -i is too trivial anyway.

Answer 1

The files that are read depends on the target user's shell. So, for example, if you sudo -u user1 -i and user1 uses csh then it'll read ~user1/.login. For ksh users it would be ~user1/.profile.

For bash users (like root) the file read is ~/.bash_profile if it exists, with a fallback to ~/.profile

eg

% sudo head -1 /root/.bash_profile /root/.profile 
==> /root/.bash_profile <==
echo RUNNING BASH_PROFILE

==> /root/.profile <==
echo RUNNING PROFILE

% sudo -i
RUNNING BASH_PROFILE
root@server:~# rm /root/.bash_profile
root@server:~# exit
logout

% sudo -i
RUNNING PROFILE
root@server:~# 

So we can see the presence of .bash_profile prevented .profile from being run. This is normal behaviour for bash login shells, whether it's accessed via a ssh login or via sudo -i.