help Get Help for Shell Builtins

commandline session

$help source
source: source filename [arguments]
    Execute commands from a file in the current shell.

    Read and execute commands from FILENAME in the current shell.  The
    entries in $PATH are used to find the directory containing FILENAME.
    If any ARGUMENTS are supplied, they become the positional parameters
    when FILENAME is executed.

    Exit Status:
    Returns the status of the last command executed in FILENAME; fails if
    FILENAME cannot be read.
$echo $?
0
$help bash
bash: help: no help topics match `bash'.  Try `help help' or `man -k bash' or `info bash'.
$