Question: PATH contains a list of directories, separated by colons. When you enter a command, the?

... shell will search those directories to find the command.

Your PATH is currently set to:

/home/uli101/bin:/usr/lib/mpi/gcc/openmpi/bin:/home/ejjaramilo/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/games:/usr/local/ant/bin:/usr/java/jdk/bin:/usr/lib/mit/bin:/usr/lib/mit/sbin:/opt/oracle12c/instantclient_12_1:/opt/oracle12c/instantclient_12_1

Change your PATH to only include the root directory '/'