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       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

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: "TOFIX:". 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,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .