gNU Bourne-Again SHell (GNU Bourne-Again SHell)
RESERVED WORDS
Reserved words are words that have a special meaning to the
shell. The following words are recognized as reserved when
unquoted and either the first word of a command (see SHELL
GRAMMAR below), the third word of a case or select command (only
in is valid), or the third word of a for command (only in and do
are valid):
! case coproc do done elif else esac fi for function if in
select then until while { } time [[ ]]
