Enable (or when -n is specified, disable) built-in shell commands. Without
built-in argument or with -p option, print enabled built-ins. With -a, print the status of all built-ins. You can disable shell commands in order to define your own functions with the same names.
Display all built-ins, both enabled and disabled.
Delete a built-in command that was previously loaded with -f.
On systems that support dynamic loading, load the new built-in command
built-in from the shared object
Disable each specified
Display enabled built-ins.
Restrict display to special built-ins defined by the POSIX standard.