If char is a value between a and z, the character sequence is translated into a single-byte value between 1 and 26. If char is any other value, the character sequence is not specially treated. An expression is a combination of operators and arguments that evaluates to a result. Expressions can be used as values in any command. An expression can combine any variable, or integer, string, or boolean values with any of the unary and binary operators in the following tables.
All unary operators take the highest precedence.
The precedence of binary operators is indicated by their position in the table. The binary operators are listed in the following table in their order of precedence. All text on a line following a semicolon is ignored. Unlike commands, they do not perform an action. The keywords are listed below.