5 Using Virtual Terminal
5.1 Accessing Remote Nodes 2 Using VT in Command Mode
Once you have accessed the remote node, you can enter command mode and issue commands to control and monitor the association. Press the appropriate key sequence to enter command mode.
On OpenVMS, enter Ctrl/@, andVT_PAD>appears as the prompt. On Digital UNIX, enter Ctrl/], and ologinappears as the prompt. To exit command mode, press Return, or enter resume.
Table 5–1 describes the commands you can use while in command mode.
Table 5–1 Command Mode Commands
Command Description
abort Sends avt-abortmessage to the remote host.
exit Sends avt-releasemessage to the remote host.
quit Same asexit.
toggle (Available only with Telnet-1988 and Generalized Telnet profiles.) Toggles between trueandfalsethe flags that control how the VT initiator responds to events. After you issue thetoggle
command, VT automatically exits command mode. You can display the current value of these flags with thedisplaycommand. Valid arguments are:
• binary— Allows 8-bit data to be both sent and received. The binaryargument also examinesinbinaryand
outbinaryto determine their state. If either or both are
false, then the appropriate value is toggled totrue. If both aretrue, then both are toggledfalse.
• inbinary— Allows 8-bit data to be received. • outbinary— Allows 8-bit data to be sent. • ? — Displays the valid toggle arguments.
help [command] Accesses online help. Enteringhelpwith no argument displays a list of command topics on which help is available. Selecting a topic provides an explanation of that topic, along with subtopics you can select for more information. You can also use the question mark (?) to access online help.
resume Exits command mode and resumes your VT association.
5.1 Accessing Remote Nodes
Table 5–1 (Cont.) Command Mode Commands
Command Description
send [item] Sends one or more special character sequences to the remote host. After you issue thesendcommand, VT automatically exits command mode. Valid arguments are:
• ao— (Available only with Telnet-1988 and Generalized Telnet profiles.) Sends thetelnet ao(Abort Output) sequence, which causes the remote system to alternately suspend and resume the sending of output to the user’s terminal. Theao
sequence does not affect the processing of the remote system. • ayt — (Available only with Telnet-1988 and Generalized
Telnet profiles.) Sends the telnet ayt(Are You There) sequence. The remote system may or may not respond. • brk — (Available only with Telnet-1988 and Generalized
Telnet profiles.) Sends the telnet brk(Break) sequence, which may have significance to the remote system.
• break— Sends the current VT break character, initially Ctrl /] for OpenVMS and Ctrl/^ for Digital UNIX.
• command— Sends the current VT initiator command character, initially Ctrl/@ for OpenVMS and Ctrl/] for Digital UNIX.
Thesend command option is useful when the command character has some meaning to the remote process. Normally, entering the character invokes the Command Line Interface. Using the send commandoption will send the character sequence to the remote host to be processed.
• ec— (Available only with Telnet-1988 and Generalized Telnet profiles.) Sends the ec(Erase Character) sequence, which causes the remote system to erase the last character entered. • el— (Available only with Telnet-1988 and Generalized Telnet
profiles.) Sends theel(Erase Line) sequence, which causes the remote system to erase the line currently being entered. • escape— Same ascommand.
• disconnect— Sends the current disconnect character, initially Ctrl/ \ for OpenVMS and Ctrl/_ for Digital UNIX. • ga— (Available only with Telnet-1988 and Generalized Telnet
profiles.) Sends thetelnet ga(Go Ahead) sequence. Often this sequence has no significance to the remote system.
• ip — (Available only with Telnet-1988 and Generalized
Telnet profiles.) Sends thetelnet ip(Interrupt Process) sequence, which causes the remote system to abort the currently running process.
• synch — (Available only with Telnet-1988 and Generalized Telnet profiles.) Sends the telnet synchsequence. This sequence causes the remote system to discard input that was previously entered but that it has not yet read.
• vtbreak— Sends avt-breakmessage. This is similar in concept to thetelnet synchsequence.
• ? — Prints out help information for thesendcommand.
5.1 Accessing Remote Nodes
Table 5–1 (Cont.) Command Mode Commands
Command Description
display [item] Enteringdisplaywith no argument displays allsetandtoggle
values, as well as the current profile, and any negotiated profile information. If you include an item as an argument, the software displays information about that item only.
show [item] Same asdisplay.
set item Sets a VT initiator variable to a specific value. Theoff value turns off the function associated with the variable. Be careful when choosing values for the variables to set, because this command overrides any previous settings for the variable. You can display the current values of variables with thedisplay
orshowcommands. Valid arguments are:
• break— Sends avt-breakmessage to the remote host. For OpenVMS, the value is initially Ctrl/].
For Digital UNIX, the value is initially Ctrl/^.
• disconnect — Sends avt-release message to the responder, and terminates the virtual terminal association. For OpenVMS, the value is initially Ctrl/\ .
For Digital UNIX, the value is initially Ctrl/_.
• command— Enters the VT initiator command mode while you are connected to a remote system.
For OpenVMS, the value is initially Ctrl/@. For Digital UNIX, the value is initially Ctrl/]. • escape— Same ascommand.
• binary, inbinaryandoutbinary— Setsitemtotrue. Seetogglecommand.
With the setcommand you can also set the value of a flag that controls how the initiator responds to events to true. Valid arguments are the same as those fortoggle.
unset item Sets a VT initiator variable to off, or the value of a flag that controls how the VT initiator responds to events tofalse. Valid arguments are the same as those forset.
mode type (Available only with Telnet-1988 and Generalized Telnet profiles.) Enters eitherline, for line-by-line mode, orcharacter, for character-by-character mode. The local host asks the remote host for permission to go into one or the other mode. The remote host enters the requested mode, if capable.
show profile Displays the current profile and any negotiated profile
information. Note that theshow profilecommand does not have the equivalentset profile, as with othershowanddisplay
commands.
Note
Not all commands or command options are available for all profiles. For example, commands that send a telnetequivalent command, such as
send ayt, will only work for theTelnetandGeneralized Telnetprofiles. See Section 1.4.3 for more information on profiles.
5.1 Accessing Remote Nodes
Table 5–2 describes the control characters for both Digital UNIX and OpenVMS systems.
Table 5–2 Control Characters
Function Digital UNIX OpenVMS
Disconnect Ctrl/_ Ctrl/\
Command3
Escape3
Ctrl/] Ctrl/@
Break Ctrl/^ Ctrl/]
Are You There† Ctrl/T
Interrupt Process† Ctrl/C Ctrl/C
Abort Output† Ctrl/O Ctrl/O
3Thecommandandescapefunctions are the same. †Applies only to Telnet and Generalized Telnet profiles.
Note
To set the Ctrl/@ key to be the break, command, or disconnect character, you must enter it using the circumflex-character notation (i.e., by entering the "^" character, followed by the "@" character.