Parameters in the Korn shell

Korn shell parameters are discussed below.

A parameter is defined as the following:

• Identifier of any of the characters asterisk (*), at sign (@), pound sign (#), question mark (?), hyphen (-), dollar sign ($), and exclamation point (!). These are called special parameters.
• Argument denoted by a number (positional parameter )
• Parameter denoted by an identifier, with a value and zero or more attributes (named parameter/variables ).

The typeset special built-in command assigns values and attributes to named parameters. The attributes supported by the Korn shell are described with the typeset special built-in command. Exported parameters pass values and attributes to the environment.

Name=Value [ Name=Value ] ...

If the -i integer attribute is set for the Name parameter, then the Value parameter is subject to arithmetic evaluation.

The shell supports a one-dimensional array facility. An element of an array parameter is referenced by a subscript. A subscript is denoted by an arithmetic expression enclosed by brackets [ ]. To assign values to an array, use set -A Name Value ... . The value of all subscripts must be in the range of 0 through 511. Arrays need not be declared. Any reference to a named parameter with a valid subscript is legal and an array will be created, if necessary. Referencing an array without a subscript is equivalent to referencing the element 0.

Positional parameters are assigned values with the set special command. The $0 parameter is set from argument 0 when the shell is invoked. The $ character is used to introduce parameters that can be substituted.