help
Display information about Bash builtin commands.
TLDR
Display the full list of builtin commands
$ help
Print instructions on how to use the while loop construct
$ help while
Print instructions on how to use the for loop construct
$ help for
Print instructions on how to use [[ ]] for conditional commands
$ help [[ ]]
Print instruction on how to use (( )) to evaluate arithmetic expressions
$ help \( \)
Print instructions on how to use the cd command
$ help cd