Source/Dot operator error on login. Possibly caused by bad byobu uninstall

Question

I am getting an error message every time I ssh into my box or run sudo -i. It looks like this for login:

login as: person
chands@ubuntu-server's password:
-bash: .: filename argument required
.: usage: . filename [arguments]
chands@ubuntu-server:~$

And like this when I execute sudo -i:

chands@ubuntu-server:~$ sudo -i
[sudo] password for chands:
-bash: .: filename argument required
.: usage: . filename [arguments]
root@ubuntu-server:~#

This error doesn't appear when I launch screen, when I use sudo to execute some other commands, when i execute sudo su and not even when I su into chands from root.

I checked ~/.bashrc for both chands and root and /etc/bash.bashrc but all three of them are the defaults and none of them have any errors with . usage.

Also, this error started happening after i removed and purged byobu from my system. I don't know if this has anything to do with the problem, but that's my point of reference before which everything worked fine.

What could be going wrong here? Any ideas anyone?

Answer 1

So the root cause of this issue was indeed byobu (well actually the lack of byobu). I do not know why but for some reason byobu didn't clean up a line from ~/.profile.This was the last line of the file: . $(which byobu-launch). Luckily I was able to find this line quite easily and quickly by doing the following (as advised by @enzotib and @geirha):

First I ran bash -xl to enter bash as a login shell(-l) in debug mode(-x). When I ran this I could see what the offending line was. Once I knew what was causing the problem I issued cat <file> | grep . $(which byobu-launch) for every file that is executed when bash starts up.

Those files are the following:

1. ~/.bashrc
2. /etc/bash.bashrc
3. ~/.profile
4. /etc/profile
5. /etc/profile.d/*
6. ~/.bash_profile
7. + all others that are included/executed by any of the above files.