Contains information about the current terminal I/O device.
Description
$ZIO contains information about the current I/O device.
For a terminal device that is a Terminal, $ZIO contains the string TRM:. If the current terminal device is connected remotely, $ZIO contains information about the remote connection.
For a terminal device connected through TELNET, $ZIO contains the following: host|port:
Argument |
Description |
host |
The remote host IP address, in either IPv4 format:nnn.nnn.nnn.nnn, where nnn is a decimal number, or in IPv6 format: h:h:h:h:h:h:h:h, where h is a hexadecimal number. Further details on IPv4 and IPv6 formats can be found in Use of IPv6 Addressing. |
port |
The remote IP port number. |
These two values are separated by a vertical bar character. For example, 127.0.0.1|23. For further information, refer to the %Library.NetworkAddressOpens in a new tab class, a subclass of the data type class %Library.StringOpens in a new tab.
If the current device is not a terminal:
-
If a file, $ZIO contains the full canonical pathname of the file.
-
If not a file, $ZIO contains the null string.
The following example returns the current device information:
SET x=$CASE($ZIO,"TRM:":"a terminal",
"CON:":"a console",
"":"neither terminal nor file")
WRITE "The current device is ",x
This special variable cannot be modified using the SET command. Attempting to do so results in a <SYNTAX> error.