Ubuntu Manpage: fmtmsg - display a message in the specified format on standard error and/or a system

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NAME

       fmtmsg  -  display  a  message  in  the specified format on standard error and/or a system
       console

SYNOPSIS

       #include <fmtmsg.h>

       int fmtmsg(long classification, const char *label, int severity,
              const char *text, const char *action, const char *tag);

DESCRIPTION

The fmtmsg() function shall display messages in a specified format instead of the
traditional printf() function.

Based on a message's classification component, fmtmsg() shall write a formatted message
either to standard error, to the console, or to both.

A formatted message consists of up to five components as defined below. The component
classification is not part of a message displayed to the user, but defines the source of
the message and directs the display of the formatted message.

classification
Contains the sum of identifying values constructed from the constants defined
below. Any one identifier from a subclass may be used in combination with a single
identifier from a different subclass. Two or more identifiers from the same
subclass should not be used together, with the exception of identifiers from the
display subclass. (Both display subclass identifiers may be used so that messages
can be displayed to both standard error and the system console.)

Major Classifications

Identifies the source of the condition. Identifiers are: MM_HARD (hardware),
MM_SOFT (software), and MM_FIRM (firmware).

Message Source Subclassifications

Identifies the type of software in which the problem is detected. Identifiers are:
MM_APPL (application), MM_UTIL (utility), and MM_OPSYS (operating system).

Display Subclassifications

Indicates where the message is to be displayed. Identifiers are: MM_PRINT to
display the message on the standard error stream, MM_CONSOLE to display the message
on the system console. One or both identifiers may be used.

Status Subclassifications

Indicates whether the application can recover from the condition. Identifiers are:
MM_RECOVER (recoverable) and MM_NRECOV (non-recoverable).

An additional identifier, MM_NULLMC, indicates that no classification component is
supplied for the message.

label Identifies the source of the message. The format is two fields separated by a
colon. The first field is up to 10 bytes, the second is up to 14 bytes.

severity
Indicates the seriousness of the condition. Identifiers for the levels of severity
are:

MM_HALT
Indicates that the application has encountered a severe fault and is halting.
Produces the string "HALT" .

MM_ERROR
Indicates that the application has detected a fault. Produces the string "ERROR" .

MM_WARNING
Indicates a condition that is out of the ordinary, that might be a problem, and
should be watched. Produces the string "WARNING" .

MM_INFO
Provides information about a condition that is not in error. Produces the string
"INFO" .

MM_NOSEV
Indicates that no severity level is supplied for the message.

text Describes the error condition that produced the message. The character string is
not limited to a specific size. If the character string is empty, then the text
produced is unspecified.

action Describes the first step to be taken in the error-recovery process. The fmtmsg()
function precedes the action string with the prefix: "TO FIX:" . The action string
is not limited to a specific size.

tag An identifier that references on-line documentation for the message. Suggested
usage is that tag includes the label and a unique identifying number. A sample tag
is "XSI:cat:146" .

The MSGVERB environment variable (for message verbosity) shall determine for fmtmsg()
which message components it is to select when writing messages to standard error. The
value of MSGVERB shall be a colon-separated list of optional keywords. Valid keywords are:
label, severity, text, action, and tag. If MSGVERB contains a keyword for a component and
the component's value is not the component's null value, fmtmsg() shall include that
component in the message when writing the message to standard error. If MSGVERB does not
include a keyword for a message component, that component shall not be included in the
display of the message. The keywords may appear in any order. If MSGVERB is not defined,
if its value is the null string, if its value is not of the correct format, or if it
contains keywords other than the valid ones listed above, fmtmsg() shall select all
components.

MSGVERB shall determine which components are selected for display to standard error. All
message components shall be included in console messages.

RETURN VALUE

       The fmtmsg() function shall return one of the following values:

       MM_OK  The function succeeded.

       MM_NOTOK
              The function failed completely.

       MM_NOMSG
              The  function  was  unable  to  generate a message on standard error, but otherwise
              succeeded.

       MM_NOCON
              The function was unable to generate a console message, but otherwise succeeded.

ERRORS

       None.

       The following sections are informative.

EXAMPLES

        1. The following example of fmtmsg():

           fmtmsg(MM_PRINT, "XSI:cat", MM_ERROR, "illegal option",
           "refer to cat in user's reference manual", "XSI:cat:001")

       produces a complete message in the specified message format:

              XSI:cat: ERROR: illegal option
              TO FIX: refer to cat in user's reference manual XSI:cat:001

        2. When the environment variable MSGVERB is set as follows:

           MSGVERB=severity:text:action

       and Example 1 is used, fmtmsg() produces:

              ERROR: illegal option
              TO FIX: refer to cat in user's reference manual

APPLICATION USAGE

       One or more message components may be systematically omitted from messages generated by an
       application by using the null value of the argument for that component.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .