FMTMSG(P) POSIX Programmer's Manual FMTMSG(P)NAMEfmtmsg - 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 con‐
stants 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 condi‐
tion. 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 char‐
acter 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 mes‐
sage. 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 deter‐
mine for fmtmsg() which message components it is to select when writing
messages to standard error. The value of MSGVERB shall be a colon-sepa‐
rated 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 oth‐
erwise 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 mes‐
sages generated by an application by using the null value of the argu‐
ment for that component.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOprintf() , the Base Definitions volume of IEEE Std 1003.1-2001,
<fmtmsg.h>
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 .
IEEE/The Open Group 2003 FMTMSG(P)
