Auto suggestion in Commands in command line

Question

I typed git s an pressed tab in ubuntu terminal and It shows git's sub-commands given below:

test: git s <tab>
shortlog  show  show-branch   stage stash status submodule

How is It happening? Auto suggestion for files is usual one. How can implement it for a command with subcommands?

Answer 1

An introduction to bash completion

This will give you idea about auto completion in shells like Bash.