ctags doesn't understand -e option (no exuberant tags option)
etags
is short for "Emacs tags", not "exuberant ctags". It sounds like you have Emacs' etags
command installed, not exuberant-ctags'.
It turns out that my system has basic ctags installed, but not exuberant-ctags. so even though some etags
command existed, exuberant-ctags is still different in some way or another.
sudo apt-get install ctags
fixed the problem
sudo apt-get install exuberant-ctags
solved the problem for me. I was running Debian Jessie on an ARM development board, cubietruck.