The shopt builtin command

The shopt builtin manages shell options, a set of boolean (on/off) configuration variables that control the behaviour of the shell.

Synopsis

shopt [-pqsu] [-o] <OPTNAME...>

Note: Some of these options and other shell options can also be set with the set builtin.

Option	Description
`-o`	Restrict the values of `<OPTNAME...>` to only those also known by the set builtin
`-p`	Print all shell options and their current value. Default.
`-q`	Quiet mode. Set exit code if named option is set. For multiple options: `TRUE` if all options are set, `FALSE` otherwise
`-s`	Enable (set) the shell options named by `<OPTNAME...>` or list all enabled options if no names are given
`-u`	Disabe (unset) the shell options named by `<OPTNAME...>` or list all disabled options if no names are given

As noted above, if only -s or -u are given without any option names, only the currently enabled (-s) or disabled (-u) options are printed.

When listing options, the exit code is TRUE (0), if all options are enabled, FALSE otherwise.

When setting/unsetting an option, the exit code is TRUE unless the named option doesn't exitst.

Enable the nullglob option:

shopt -s nullglob

The shopt command is not portable accross different shells.