Introduction to the Terminal
The Terminal is a simple command-line interface for entering Caché commands and displaying current values. It is useful during learning, development, and debugging.
This chapter discusses the following topics:
If the Terminal displays a dialog box with the message Spy Mode On, this means that you have accidentally pressed Alt+Shift+S. To exit this mode, press Alt+Shift+S again. This mode is not for general use and is not documented.
Also, if the Terminal appears to be unresponsive, you may have pressed Ctrl+S, which pauses the automatic scrolling. If so, press Ctrl+Q to resume.
User Account That Owns the Terminal Process
In Caché versions 2015.2 and later, the Caché process is owned by the user that is logged in to Windows and is running the Terminal program (cterm.exe).
In Caché versions 2015.1 and earlier:
Beginning with Windows Vista, and including Windows Vista, Windows Server 2008, and Windows 7, the Caché process that serves the Terminal connection is owned by the user account in which the Caché control service runs.
Before Windows Vista, the Caché process is owned by the user that is logged in to Windows and is running the Terminal program (cterm.exe).
In all cases, all environment variables and shared drive letter designations are those defined by the user that is running the Terminal.
Starting the Terminal
You can use the Terminal interactively or in batch mode.
To use the Terminal interactively, do one of the following:
To work with the Terminal using a local database, select the InterSystems Launcher and then select Terminal.
To work with the Terminal using a database on a remote server, select the InterSystems Launcher and then select Remote System Access > Terminal. Then select a server name.
Or select the InterSystems Launcher, select Remote System Access > Telnet. Then log on to the Caché system with your username and password.
For more information and additional options, see the chapter “Connecting to Remote Servers” in the Caché System Administration Guide.
In either case, you then see the Terminal window. The prompt displayed in this window indicates the namespace in which you are currently working. For example:
In batch mode, you invoke the Terminal from the operating system command line, passing to it the name of a script file to run. This mode is not available for all operating systems.
The Terminal was designed to work with Caché applications. It uses two methods to communicate with Caché: local and network. The title bar indicates the communication mode currently in use.
Local communication is used when the Terminal communicates with the Caché server with which it was installed. In this case, the title bar displays Cache TRM:pid(instancename) where:
pid is the process ID of the Caché process with which the Terminal is communicating.
instancename is the Caché instance in which the process is running.
Network communication uses the TELNET protocol over TCP/IP to communicate with either a Windows Caché server or with a UNIX® host. In this case, the title bar displays (server NT — Caché Telnet) where server is the host name of the remote server.
The communications stack for Caché is Winsock. Winsock is a network programming interface for Microsoft Windows which is based on the socket paradigm popularized in the Berkeley Software Distribution (BSD). The host entry can be either from the local file, an IP address, or, if the Winsock implementation has access to a name server, a general host name. The host name may be followed by an optional #nnn to specify a nonstandard port number.
Errors reported from this communications mode are the names of the Winsock error codes. For example, WSAECONNREFUSED means the connection was refused.
In the Terminal, you can enter ObjectScript commands of all kinds. For example:
set dirname = "c:\test"
set obj=##class(Test.MyClass).%New() write obj.Prop1
The Terminal implicitly issues the Use 0 command after each line you enter. This means that if you issue a Use command to direct output to some other device, that command is essentially ignored.
Also, large input buffers may defer the action of keys that attempt to stop the input flow such as Ctrl-C or Ctrl-S. This is also dependent on processor and connection speed. A special effort was made to respond to keystrokes before host input.
You can also run Terminal scripts, which are files with the extension .scr existing in your file system. The Terminal provides a small set of commands you can use in these scripts, including a command that sends a Caché command to the Terminal, as if you had typed it manually.
The ZWELCOME Routine
When the Terminal begins execution, the code checks for the existence of a routine called ZWELCOME in the %SYS namespace. If such a routine is found, it is invoked immediately prior to the terminal login sequence, if any. The name of the routine implies its intended use, as a custom identification and welcome message to users.
The installation of ZWELCOME into the %SYS namespace requires an individual with administrator privileges and write access to the CACHESYS database.
The ZWELCOME routine executes in the %SYS namespace with an empty $USERNAME and with $ROLES set to %ALL. Take care to ensure that the failure modes of ZWELCOME are benign. Also, this routine should not modify the $ROLES variable.
Here is a simple example:
ZWELCOME() PUBLIC ; ; Example Write ! Set ME = ##class(%SYS.ProcessQuery).%OpenId($JOB) Write "Now: ", $ZDATETIME($HOROLOG, 3, 1), ! Write "Pid/JobNo: ", ME.Pid, "/", ME.JobNumber, ! Write "Priority: ", ME.Priority, ! Quit
The Startup Namespace
When you first start the Terminal, it opens in a particular namespace. This option is controlled by the Startup Namespace option of the user definition. See the chapter “Users” in the Caché Security Administration Guide.
The command prompt displays the current namespace, such as:
To change to a new namespace, use the ZNSPACE command (which has a short form of ZN
USER>ZN "SAMPLES" SAMPLES>
The argument for the ZNSPACE command is a single string that is the name of the namespace to change to. If you enter an invalid namespace name, ZNSPACE throws a <NAMESPACE> error. See the ZNSPACE reference page in the Caché ObjectScript Reference for more information.
The Terminal Prompt
As noted previously, the Terminal prompt indicates the namespace in which you are currently working. The prompt may display additional information, to indicate the transaction level or the program stack level.
The Transaction Level
If you are within a transaction, a prefix is appended to the prompt to indicate the transaction level. The prefix is of the form TLn:, where n is the transaction level. For example, if you are in the User namespace and you enter the ObjectScript command TSTART, the prompt changes as follows:
If you exit the Terminal, that rolls back the transaction.
The Program Stack Level
If an error occurs, a suffix is added to the prompt to indicate the program stack level. For example:
The TSQL Shell
To access the TSQL shell, type DO $SYSTEM.SQL.TSQLShell() and press Enter. The prompt is then displayed with the string (:TSQL), as follows:
USER>DO $SYSTEM.SQL.TSQLShell() Current settings :- No current settings Compiler is NEW USER:TSQL>
To exit the TSQL shell, enter the ^ command.
For information on the TSQL shell, see the Caché Transact-SQL (TSQL) Migration Guide.
The MV Shell
To access the MV shell, type MV and press Enter. The prompt is then displayed with a colon (:) at the end rather than a right angle bracket (>), as follows:
If the MV shell has not yet been initialized, you may see messages before this prompt.
To exit the MV shell, enter the Quit command.
For information on the MV shell, see the chapter “Starting MultiValue” in the book Using the MultiValue Features of Caché.
Do not open another MV shell from within an MV shell.
In the Terminal, you can also open various operating-system shells. To do so, type ! and press Enter. The Terminal then opens your default operating-system shell, and the prompt shows the working directory. For example:
On Macintosh, you cannot open the C-shell this way; you receive a permission denied error. You can, however, use other shells (Bash, Bourne, or Korn).
To exit the shell, use the quit or exit command as appropriate for the shell.
Interrupting Execution in the Terminal
To interrupt the Terminal and stop any foreground execution, use one of the following key combinations:
Ctrl+C — Use this if the Windows edit accelerators option is not enabled.
Ctrl+Shift+C — Use this if the Windows edit accelerators option is enabled.
For information on Windows edit accelerators option, see the section “User Settings,” in the chapter “Controlling the Appearance and Behavior of the Terminal.”
Exiting the Terminal
To exit the Terminal, do either of the following:
Select File > Exit.
This causes this copy of the Terminal to exit, closing any open files and stopping any foreground execution.
If this Terminal was connected to a server at startup, it exits on its own when the communications channel is closed.
If you accessed this Terminal via Cache Telnet in the InterSystems Launcher, then it does not exit automatically when the communications channel is closed; instead it remains active so you that can connect again via the Connect menu.