Updated: 11 December 1998 |
OpenVMS System Messages: Companion Guide for Help
Message Users
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The chapters in this part of the manual provide tutorial information about OpenVMS system messages and explain how to use the Help Message utility to access online message descriptions.
The OpenVMS operating system provides a centralized error message facility. When you type a command at the terminal or execute an image that results in an error, the system locates the message associated with the error and displays it.
The Help Message (MSGHLP) utility, described in Chapter 2, allows you to access online messages documentation from the DCL prompt. Part 2 of this manual describes messages that can occur before the operating system and Help Message are fully functional. Messages are ordered alphabetically by message identification (see Section 1.1); exceptions to this rule are noted in Section 1.1.1.
For users who do not have Help Message installed, Section 1.3
explains how to retrieve a system message. This chapter also describes
how to recover from typical error conditions (see Section 1.5).
1.1 Format of System Messages
Most messages displayed by the OpenVMS operating system have the following format:
%facility-s-identification, text [-facility-s-identification, text] |
A percent sign (%) prefixes the main message, and a hyphen (-) prefixes any secondary messages that provide additional information about the error.
For example, the HELP/MESSAGE command calls OpenVMS Record Management Services (RMS) to access the database. If the database file cannot be found, the MSGHLP facility displays a message indicating that it cannot access the file; an RMS message and a SYSTEM message follow to indicate the reason for the failure. In the following example, a HELP/MESSAGE command includes the /LIBRARY qualifier to specify a private database, which MSGHLP cannot find:
$ HELP/MESSAGE/LIBRARY=TOOLS:[MYPROJ]MYMESSAGES.MSGHLP$DATA ACCVIO %MSGHLP-F-MDFERR, error accessing Help Message database file "TOOLS:[MYPROJ] MYMESSAGES.MSGHLP$DATA" -RMS-E-FNF, file not found -SYSTEM-W-NOSUCHFILE, no such file |
Any or all of the message fields can be suppressed by using the SET MESSAGE command (see online help or the OpenVMS DCL Dictionary). The message fields are as follows:
facility
An OpenVMS facility or component name.s
A severity level indicator having one of the following values:
Code Meaning Description S Success The system has successfully performed your request. In some cases, the command processing continues after the message is issued. I Information The system has performed your request. The message provides information about the process. W Warning The command may have performed some, but not all, of your request. The message may suggest that you verify the command or the program output. E Error The output or program result is incorrect, but the system may attempt to continue execution. F Fatal (severe) The system cannot continue to execute the request. identification
A one-word code identifying the message---often an abbreviation of the message text. Messages described in this manual are typically alphabetized by message identification. Section 1.1.1 describes some exceptions.text
Text of the message; usually describes the condition that produced the message.
Some messages have no identification. Others have no facility code, severity level, or identification. In this manual, such messages are alphabetized by the first word in the message---whether it is the facility name or the message text.
Facilities that often include the facility name, but no identification, in their messages are:
For example, the following message is alphabetized under "SYSBOOT--E--Device":
SYSBOOT-E-Device names not allowed |
The following facilities display some or all of their messages without facility name, severity level, and identification:
For example, the following cluster port driver message is alphabetized under "Port":
Port Power Down |
Messages are displayed on the current device, which is identified by the logical name SYS$OUTPUT. For an interactive user, this device is normally the terminal; for batch job users, it is the batch job log file.
If the logical device SYS$ERROR is different from SYS$OUTPUT, the
system writes informational, warning, error, and fatal system messages
to that device as well. For example, if you execute a command procedure
interactively and specify the /OUTPUT qualifier, the system defines the
file you specified as SYS$OUTPUT for the procedure. SYS$ERROR remains
assigned to your current error device. Then, if any errors occur during
the execution of the command procedure, the error messages are
displayed on your terminal and are entered in the specified file.
1.3 Retrieving a System Message
When a DCL command, command procedure, or applications program completes execution, it returns a condition code. The condition code indicates the execution status of the command---whether it executed successfully or resulted in an error.
Each condition code corresponds to a system message. The command interpreter saves the condition code as a 32-bit longword defined as the reserved global symbol $STATUS. The condition code stored in $STATUS is a hexadecimal number conforming to the format of an OpenVMS message code:
By default, the HELP/MESSAGE command accesses the value stored in $STATUS and displays the corresponding message. The following paragraphs explain how you can access similar information if the Help Message utility is not installed on your system.
The lexical function F$MESSAGE returns the message associated with a condition code. To display the message for the current code on the default output device, use the following command:
$ WRITE SYS$OUTPUT F$MESSAGE($STATUS) %SYSTEM-F-POWERFAIL, power failure occurred |
If you prefer to obtain the current value of $STATUS, use this command:
$ SHOW SYMBOL $STATUS $STATUS == "%X00000364" |
If you know the condition code for a message, you can use F$MESSAGE to translate the code to its associated message. For example:
$ WRITE SYS$OUTPUT F$MESSAGE(%X00000001) %SYSTEM-S-NORMAL, normal successful completion |
You can omit leading zeros when specifying a code to F$MESSAGE.
However, the characters "%X" are necessary to identify a
numeral as hexadecimal.
1.4 Exception Conditions
During the execution of an image, the image can incur a fatal error known as an exception condition. When an exception condition occurs, the system takes special action.
If the image has not declared a condition handler, the system forces
the image to exit and displays a message indicating the reason for the
exception. The message includes the contents of these locations at the
time of the exception: the program counter (PC) and processor status
(PS) on OpenVMS Alpha systems, or the program counter (PC) and
processor status longword (PSL) on OpenVMS VAX systems. This message is
followed by a traceback; the system displays the status of the call
frames on the stack so that you can locate the procedure where the
condition occurred. Refer to the OpenVMS Programming Concepts Manual for a more detailed
discussion of condition handling.
1.5 Recovery Procedures
Error messages generally occur for the following reasons:
When an error occurs following interactive command entry, you must reenter the command. Messages from the command interpreter are usually followed by a display of the portion of the command line that is rejected. Correct this portion of the line before you reenter the command.
Errors that occur while a command is executing can indicate that you have entered an invalid value for a parameter or qualifier. In these cases, you can use the DCL command HELP or consult the OpenVMS DCL Dictionary to determine the legal values before you try to reenter the command.
Errors in file specifications or device names can occur when you enter a file name in a command that has a default file type, but the file name is currently defined as a logical name. When the system translates the logical name, the resulting file specification may not be valid within the context of the command.
The syntax of the file specification can be invalid for any of the following reasons:
If the Set Resource Wait Mode ($SETRWM) system service is enabled (default mode) and a required resource such as dynamic memory is unavailable, the process is normally placed in a wait state until the resource becomes available. However, under certain program conditions, the programmer can choose to disable the resource wait mode so that when such a condition occurs, control returns immediately to the calling program with an error status.
Other resources such as files, privileges, or devices are not subject to resource wait mode, and their unavailability or absence always causes an error.
How a program responds to the unavailability of a resource depends
primarily on the application and the particular service called. In some
instances, the program may be able to continue execution and retry the
service later. Or, it may be necessary only to note that the program is
required to wait.
1.5.3 Recovering from Programming Errors
If a program image terminates abnormally, you can get some information about the error from the message. When a program image exits, the command interpreter uses the current value of general register 0 to obtain information about the exit status. If it is an abnormal (or error) exit, the system message associated with the register 0 value is displayed.
Programming errors can be caused by the following conditions:
The OpenVMS Debugger can help you discover and correct programming
errors. For details on how to use the debugger, refer to the
OpenVMS Debugger Manual.
1.5.4 Reporting System Software or Hardware Errors
When a message notifies you that a system software or hardware error has occurred, action is required by the system operator or system manager. If a hardware device is not operational, inform the system manager. If you encounter a software error, keep any system dump files and other relevant information, and contact a DIGITAL support representative.
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