bin/launch_tera.sh and bin/teracli can not work properly

The commands in the example/bin should be executed properly no matter which directory they run in.
When I use bin/teracli, it shows `hasn't specify the flagfile`. But `./teracli` can work.

Start with example/bin/launch_tera.sh and example/bin/teracli, then run the commands from both the repository directory and another directory to reproduce the flagfile error. Done means both commands execute properly regardless of the caller's working directory, while preserving the existing behavior that works with ./teracli.

Written by the indexing model from the issue text.