(features.info)Korn Shell Variables

Korn Shell Variables
====================

`REPLY'
     The default variable for the `read' builtin.

`RANDOM'
     Each time this parameter is referenced, a random integer is
     generated.  Assigning a value to this variable seeds the random
     number generator.

`SECONDS'
     This variable expands to the number of seconds since the shell was
     started.  Assignment to this variable resets the count to the
     value assigned, and the expanded value becomes the value assigned
     plus the number of seconds since the assignment.

`PS3'
     The value of this variable is used as the prompt for the `select'
     command.

`PS4'
     This is the prompt printed before the command line is echoed when
     the `-x' option is set (Note: The Set Builtin.).

`PWD'
     The current working directory as set by the `cd' builtin.

`OLDPWD'
     The previous working directory as set by the `cd' builtin.

`TMOUT'
     If set to a value greater than zero, the value is interpreted as
     the number of seconds to wait for input after issuing the primary
     prompt.  Bash terminates after that number of seconds if input does
     not arrive.