At the Bash command line interface, there is the concept of programmable completion and regular file/directory completion. This means that when you press the <TAB>, the alternatives can be provided by a custom program or the filesystem hierarchy.
There is always the chance that a program may introduce undesirable behavior to your auto-completion, and if this is case, you can disable ALL program completion and just rely on the fallback file/directory choices with the command below.
shopt -u progcomp
If you need to see what script a program is using for auto-completion:
# show script used for autocomplete for specific program complete -p <program> # show autocomplete scripts for all programs complete
REFERENCES
gnu.org, programmable completion
stackoverflow.com, bash tab completion broken
unix.stackexchange, list of programs for autocompletion
stackexchange.com, shows modification of complete
NOTES
On Ubuntu, this script loads autocomplete for all services: /usr/share/bash-completion/bash_completion