Copy contents of dart-bash-completion.sh file to ~/.bash_completion.
open new terminal and try auto completion.
bash$ dart --version
Dart SDK version: 2.17.1 (stable) (Tue May 17 17:58:21 2022 +0000) on "linux_x64"
bash$ dart [tab]
analyze create doc format pub test
compile devtools fix migrate run
bash$ dart pub [tab]
add deps get login outdated remove upgrade
cache downgrade global logout publish token
bash$ dart pub add -[tab]
--dev --git-ref --no-offline --precompile -h
--directory= --git-url --no-precompile --sdk= -n
--dry-run --help --offline -C
--git-path --hosted-url --path -d - dart command execution a bit slow to complete ...