fmtmsg(3p) — Linux manual page


FMTMSG(3P)              POSIX Programmer's Manual             FMTMSG(3P)

PROLOG         top

       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         top

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

SYNOPSIS         top

       #include <fmtmsg.h>

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

DESCRIPTION         top

       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.

                   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

                   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-

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

       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

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

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

                   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         top

       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         top


       The following sections are informative.

EXAMPLES         top

        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:


           and Example 1 is used, fmtmsg() produces:

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


       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         top




SEE ALSO         top


       The Base Definitions volume of POSIX.1‐2017, fmtmsg.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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 .

IEEE/The Open Group               2017                        FMTMSG(3P)

Pages that refer to this page: fmtmsg.h(0p)