NAME

cls - clear the screen

SYNOPSIS

cls [NumExpr]

DESCRIPTION

Cls clears the screen of the user’s terminal.  The optional argument NumExpr is unused but may appear for the sake of compatibility.  It determines the proper way of clearing the screen by examining the environment variable TERM and looking up the terminal in the system’s terminal capability database, either /etc/termcap or /usr/lib/terminfo. 

USAGE NOTES

If cls is unable to determine the terminal type or is unable to access the terminal capability database, it does nothing. 

If the environment variable BASECHO is set to a non-null value when a Basmark QuickBASIC program begins executing, the BASIC input/output facility operates differently in order to support half-duplex terminals such as the IBM 3278.  In this modified behavior of the input/output facility, the terminal modes are not altered.  Cls may fail to work properly under some circumstances because of post-processing by the terminal driver. 

from The Basmark QuickBASIC Programmer’s Manual by Lawrence Leinweber