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FMTMSG(3)              FreeBSD Library Functions Manual              FMTMSG(3)

NAME
     fmtmsg - display a detailed diagnostic message

LIBRARY
     Standard C Library (libc, -lc)

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 displays a detailed diagnostic message, based on
     the supplied arguments, to stderr and/or the system console.

     The classification argument is the bitwise inclusive OR of zero or one of
     the manifest constants from each of the classification groups below.  The
     Output classification group is an exception since both MM_PRINT and
     MM_CONSOLE may be specified.

     Output

             MM_PRINT        Output should take place on stderr.

             MM_CONSOLE      Output should take place on the system console.

     Source of Condition (Major)

             MM_HARD         The source of the condition is hardware related.

             MM_SOFT         The source of the condition is software related.

             MM_FIRM         The source of the condition is firmware related.

     Source of Condition (Minor)

             MM_APPL         The condition was detected at the application
                             level.

             MM_UTIL         The condition was detected at the utility level.

             MM_OPSYS        The condition was detected at the operating
                             system level.

     Status

             MM_RECOVER      The application can recover from the condition.

             MM_NRECOV       The application is unable to recover from the
                             condition.

     Alternatively, the MM_NULLMC manifest constant may be used to specify no
     classification.

     The label argument indicates the source of the message.  It is made up of
     two fields separated by a colon (`:').  The first field can be up to 10
     bytes, and the second field can be up to 14 bytes.  The MM_NULLLBL
     manifest constant may be used to specify no label.

     The severity argument identifies the importance of the condition.  One of
     the following manifest constants should be used for this argument.

           MM_HALT         The application has confronted a serious fault and
                           is halting.

           MM_ERROR        The application has detected a fault.

           MM_WARNING      The application has detected an unusual condition,
                           that could be indicative of a problem.

           MM_INFO         The application is providing information about a
                           non-error condition.

           MM_NOSEV        No severity level supplied.

     The text argument details the error condition that caused the message.
     There is no limit on the size of this character string.  The MM_NULLTXT
     manifest constant may be used to specify no text.

     The action argument details how the error-recovery process should begin.
     Upon output, fmtmsg() will prefix "TO FIX:" to the beginning of the
     action argument.  The MM_NULLACT manifest constant may be used to specify
     no action.

     The tag argument should reference online documentation for the message.
     This usually includes the label and a unique identifying number.  An
     example tag is "BSD:ls:168".  The MM_NULLTAG manifest constant may be
     used to specify no tag.

RETURN VALUES
     The fmtmsg() function returns MM_OK upon success, MM_NOMSG to indicate
     output to stderr failed, MM_NOCON to indicate output to the system
     console failed, or MM_NOTOK to indicate output to stderr and the system
     console failed.

ENVIRONMENT
     The MSGVERB (message verbosity) environment variable specifies which
     arguments to fmtmsg() will be output to stderr, and in which order.
     MSGVERB should be a colon (`:') separated list of identifiers.  Valid
     identifiers include: label, severity, text, action, and tag.  If invalid
     identifiers are specified or incorrectly separated, the default message
     verbosity and ordering will be used.  The default ordering is equivalent
     to a MSGVERB with a value of "label:severity:text:action:tag".

EXAMPLES
     The code:

           fmtmsg(MM_UTIL | MM_PRINT, "BSD:ls", MM_ERROR,
               "illegal option -- z", "refer to manual", "BSD:ls:001");

     will output:

           BSD:ls: ERROR: illegal option -- z
           TO FIX: refer to manual BSD:ls:001

     to stderr.

     The same code, with MSGVERB set to "text:severity:action:tag", produces:

           illegal option -- z: ERROR
           TO FIX: refer to manual BSD:ls:001

SEE ALSO
     err(3), exit(3), strerror(3)

STANDARDS
     The fmtmsg() function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY
     The fmtmsg() function first appeared in FreeBSD 5.0.

BUGS
     Specifying MM_NULLMC for the classification argument makes little sense,
     since without an output specified, fmtmsg() is unable to do anything
     useful.

     In order for fmtmsg() to output to the system console, the effective user
     must have appropriate permission to write to /dev/console.  This means
     that on most systems fmtmsg() will return MM_NOCON unless the effective
     user is root.

FreeBSD 11.1-RELEASE-p4         August 5, 2002         FreeBSD 11.1-RELEASE-p4
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