# fmtmsg

## PROLOG



           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: **"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.
    


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