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Managing Terminals  



To manage terminals, perform the following tasks:

The following sections explain setting terminal characteristics and setting up virtual terminals.

Setting Terminal Characteristics  

Terminal device characteristics--for example, the number of characters displayed on a line--have certain default values. Changing these values might be necessary, depending on the characteristics you use with each terminal.

To change the terminal device characteristics, use a SET TERMINAL command with the appropriate qualifiers in the following format: SET TERMINAL[/qualifier,...] [device-name[:]]

For example, the following command indicates that the width of terminal lines is 132 characters and that the size of each page is 60 lines. The /NOBROADCAST qualifier disables the reception of broadcast messages. The /PERMANENT qualifier allows you to keep terminal characteristics between terminal sessions. (You must reset characteristics each time the system reboots by adding these commands to a site-specific startup command procedure.)

$ SET TERMINAL/WIDTH=132/PAGE=60/NOBROADCAST/PERMANENT
For more detailed information about the SET TERMINAL command and its qualifiers, refer to the HP OpenVMS DCL Dictionary.

Setting Default Characteristics with System Parameters  

To change the default terminal characteristics for all terminals on a node, you can specify values for the system parameters TTY_DEFCHAR and TTY_DEFCHAR2. For more information about setting and using system parameters, see HP OpenVMS System Manager's Manual, Volume 2: Tuning, Monitoring, and Complex Systems.

Setting Characteristics in System Startup  

To execute SET TERMINAL commands each time your system boots, add these commands to a site-specific startup command procedure. If your configuration is simple, you can add the commands to SYSTARTUP_VMS.COM. If your configuration requires a large number of commands, create a separate command procedure (for example, TERM_SETUP.COM) and execute it from the SYSTARTUP_VMS.COM. When the device setup command procedure finishes executing, control returns to SYSTARTUP_VMS.COM.


CautionHP recommends that you limit the number of SET TERMINAL commands you include in startup command procedures. Large numbers (for example, hundreds) of SET TERMINAL commands can significantly slow down system startup. If you have a large number of terminals, change the default characteristics using the system parameters TTY_DEFCHAR and TTY_DEFCHAR2 as explained in Setting Default Characteristics with System Parameters.

You may want to include comments to provide the names of terminal owners, as shown in the following example.

Example

The following example provides sample commands you could include in your startup procedure to set up terminal devices:

$ SET TERMINAL TTC2:/SPEED=300/DEVICE_TYPE=LA36/PERMANENT  !JONES
$ SET TERMINAL TTD1:/SPEED=9600/PERMANENT                  !WRENS
$ SET TERMINAL TTD4:/SPEED=1200/PERMANENT                  !JRSMITH
$ SET TERMINAL TTG4:/SPEED=1200/MODEM/PERMANENT            !DIALUP1

Managing Virtual Terminals  

Virtual terminals allow users to disconnect from a physical terminal without terminating a process; the process remains active on a virtual terminal. Virtual terminals are used for the following purposes:

Enabling Virtual Terminals

On VAX systems, you set up virtual terminals by entering the following commands:

$ RUN SYS$SYSTEM:SYSGEN
SYSGEN> CONNECT VTA0/NOADAPTER/DRIVER=TTDRIVER
SYSGEN> EXIT 
On Alpha and I64 systems, you set up virtual terminals by entering the following commands:
$ RUN SYS$SYSTEM:SYSMAN
 
SYSMAN> IO CONNECT VTA0/NOADAPTER/DRIVER=SYS$TTDRIVER
 
SYSMAN> EXIT 
Virtual terminals are identified by the VTAn: device name. After the SYSGEN or IOGEN command is entered, any terminal with the TT2$M_DISCONNECT characteristic set prior to login is treated as a virtual terminal.
NoteLAT terminals (LTAn:) can be disconnected if the TT2$M_DISCONNECT characteristic is set, but remote terminals (RTAn:) cannot be disconnected.

You can set the TT2$M_DISCONNECT characteristic in one of two ways:

Controlling the Use of Virtual Terminals

You can control the use of virtual terminal sessions in the following ways:

Using Virtual Terminals for Dynamic Asynchronous DECnet for OpenVMS (VAX Only)  

Virtual terminals are required for dynamic asynchronous DECnet communication. A dynamic asynchronous line differs from a static asynchronous line or other DECnet line in that it is normally switched on for network use only for the duration of a dialup connection between two nodes. Dynamic switching of terminal lines to asynchronous DDCMP lines can occur if the following requirements are met:

See the DECnet-Plus for OpenVMS Applications Installation and Advanced Configuration for a detailed description of the procedure for setting up dynamic asynchronous DECnet lines.

Determining the Physical Terminal Type of a Virtual Terminal  

You can determine the physical terminal type associated with a virtual terminal. Because both direct connect and LAT lines can be virtual, you might not know the terminal characteristics of a LAT terminal at system startup time. You can set the characteristics of direct connect lines at system startup; however, you must enter a SET TERMINAL/INQUIRE command to determine the characteristics of a LAT line. (See the HP OpenVMS System Manager's Manual, Volume 2: Tuning, Monitoring, and Complex Systems for more information about LAT software.)


NoteUsing the command SET TERMINAL/INQUIRE clears the type-ahead buffer.

The following command procedure determines the physical terminal characteristics of both direct and LAT lines at system startup. Insert the following lines in your systemwide login procedure (SYLOGIN.COM). (This procedure assumes that your startup procedure has set all switches and LAT lines to "unknown." )
$ DEVCLASS = 'F$GETDVI ("SYS$COMMAND","DEVCLASS")'
$ IF DEVCLASS .ne. 66 then goto alldone   !Not a terminal
$ DEVTYPE = 'F$GETDVI ("SYS$COMMAND","DEVTYPE")'
$ IF DEVTYPE .ne. 0 then goto got_devtype
$ SET TERMINAL/INQUIRE   !Try to determine the device type
$ DEVTYPE = 'F$GETDVI ("SYS$COMMAND","DEVTYPE")'
$ got_devtype:
$! Can now dispatch on 'devtype' to do different things depending
$! on the type of terminal.
$ alldone:
You can uniquely identify a LAT terminal by using the F$GETDVI lexical function and specifying the item TT_ACCPORNAM. The function returns the terminal server node name and port name.
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