expr1  expr2 
 Return the evaluation of expr1 if it is neither an empty string nor zero; otherwise, returns the evaluation of expr2. 
expr1 & expr2 
 Return the evaluation of expr1 if neither expression evaluates to an empty string or zero; otherwise, returns zero. 
expr1 "{=, >, >=, <, <=, !=}" expr2 
 Return the results of integer comparison if both arguments are integers; otherwise, returns the results of string comparison using the localespecific collation sequence. The result of each comparison is 1 if the specified relation is true, or 0 if the relation is false. 
expr1 "{+, }" expr2 
 Return the results of addition or subtraction of integervalued arguments. 
expr1 "{*, /, %}" expr2 
 Return the results of multiplication, integer division, or remainder of integervalued arguments. 
expr1: expr2 
 The ":" operator matches expr1 against expr2, which must be a basic regular expression. The regular expression is anchored to the beginning of the string with an implicit "^". If the match succeeds and the pattern contains at least one regular expression subexpression ""\(...\)"", the string corresponding to ""\1"" is returned; otherwise the matching operator returns the number of characters matched. If the match fails and the pattern contains a regular expression subexpression the null string is returned; otherwise 0. 
