This is an extract from the bash manual obtained by typing 'man bash'.


       case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
	      A case command first expands word, and tries to match it against
	      each pattern in turn, using the same matching rules as for path
	      name expansion (see Pathname  Expansion  below).	 The  word  is
	      expanded	using  tilde  expansion, parameter and variable expan
	      sion, arithmetic	substitution,  command	substitution,  process
	      substitution  and  quote	removal.   Each  pattern  examined  is
	      expanded using tilde expansion, parameter  and  variable	expan
	      sion, arithmetic substitution, command substitution, and process
	      substitution.  If the shell option nocasematch is  enabled,  the
	      match  is  performed  without  regard  to the case of alphabetic
	      characters.  When a match is found, the  corresponding  list  is
	      executed.   After  the  first  match,  no subsequent matches are
	      attempted.  The exit status is zero if no pattern matches.  Oth
	      erwise,  it  is  the exit status of the last command executed in
	      list.