fmtmsg(3C) Standard C Library Functions fmtmsg(3C)NAMEfmtmsg - display a message on stderr or 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 writes a formatted message to stderr, to the con‐
sole, or to both, on a message's classification component. It can be
used instead of the traditional printf(3C) interface to display mes‐
sages to stderr, and in conjunction with gettxt(3C), provides a simple
interface for producing language-independent applications.
A formatted message consists of up to five standard components ( label,
severity, text, action, and tag) as described below. The classification
component is not part of the standard message displayed to the user,
but rather defines the source of the message and directs the display of
the formatted message.
classification Contains identifiers from the following groups of major
classifications and subclassifications. Any one identi‐
fier from a subclass may be used in combination by
ORing the values together 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 stderr and the system
console).
· "Major classifications" identify the source of the
condition. Identifiers are: MM_HARD (hardware),
MM_SOFT (software), and MM_FIRM (firmware).
· "Message source subclassifications" identify the
type of software in which the problem is spotted.
Identifiers are: MM_APPL (application), MM_UTIL
(utility), and MM_OPSYS (operating system).
· "Display subclassifications" indicate 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. Neither, either, or both iden‐
tifiers may be used.
· "Status subclassifications" indicate whether the
application will recover from the condition. Iden‐
tifiers are: MM_RECOVER (recoverable) and MM_NRE‐
COV (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 of
this component is two fields separated by a colon. The
first field is up to 10 characters long; the second is
up to 14 characters. Suggested usage is that label
identifies the package in which the application resides
as well as the program or application name. For exam‐
ple, the label UX:cat indicates the UNIX System V pack‐
age and the cat(1) utility.
severity Indicates the seriousness of the condition. Identifiers
for the standard levels of severity are:
· MM_HALT indicates that the application has encoun‐
tered a severe fault and is halting. Produces the
print string HALT.
· MM_ERROR indicates that the application has
detected a fault. Produces the print string ERROR.
· MM_WARNING indicates a condition out of the ordi‐
nary that might be a problem and should be
watched. Produces the print string WARNING.
· MM_INFO provides information about a condition
that is not in error. Produces the print string
INFO.
· MM_NOSEV indicates that no severity level is sup‐
plied for the message.
Other severity levels may be added by using the add‐
severity() routine.
text Describes the condition that produced the message. The
text string is not limited to a specific size.
action Describes the first step to be taken in the error
recovery process. fmtmsg() precedes each action string
with the prefix: TOFIX:. The action string is not lim‐
ited to a specific size.
tag An identifier which references on-line documentation
for the message. Suggested usage is that tag includes
the label and a unique identifying number. A sample tag
is UX:cat:146.
Environment Variables
The MSGVERB and SEV_LEVEL environment variables control the behavior of
fmtmsg() as follows:
MSGVERB This variable determines which message components
fmtmsg() selects when writing messages to stderr. Its
value is a colon-separated list of optional keywords
and can be set as follows:
MSGVERB=[keyword[:keyword[:...]]]
export MSGVERB
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() includes that component in the message
when writing the message to stderr. If MSGVERB does not
include a keyword for a message component, that compo‐
nent is not 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 key‐
words other than the valid ones listed above, fmtmsg()
selects all components.
The first time fmtmsg() is called, it examines MSGVERB
to determine which message components are to be
selected when generating a message to write to the
standard error stream, stderr. The values accepted on
the initial call are saved for future calls.
The MSGVERB environment variable affects only those
components that are selected for display to the stan‐
dard error stream. All message components are included
in console messages.
SEV_LEVEL This variable defines severity levels and associates
print strings with them for use by fmtmsg(). The stan‐
dard severity levels listed below cannot be modified.
Additional severity levels can also be defined, rede‐
fined, and removed using addseverity() (see addsever‐
ity(3C)). If the same severity level is defined by both
SEV_LEVEL and addseverity(), the definition by add‐
severity() takes precedence.
0 (no severity is used)
1 HALT
2 ERROR
3 WARNING
4 INFO
The SEV_LEVEL variable can be set as follows:
SEV_LEVEL=[description[:description[:...]]]
export SEV_LEVEL
where description is a comma-separated list containing
three fields:
description=severity_keyword,level,printstring
The severity_keyword field is a character string that
is used as the keyword on the -s severity option to the
fmtmsg(1) utility. (This field is not used by the
fmtmsg() function.)
The level field is a character string that evaluates to
a positive integer (other than 0, 1, 2, 3, or 4, which
are reserved for the standard severity levels). If the
keyword severity_keyword is used, level is the severity
value passed on to the fmtmsg() function.
The printstring field is the character string used by
fmtmsg() in the standard message format whenever the
severity value level is used.
If a description in the colon list is not a three-field
comma list, or if the second field of a comma list does
not evaluate to a positive integer, that description in
the colon list is ignored.
The first time fmtmsg() is called, it examines the
SEV_LEVEL environment variable, if defined, to deter‐
mine whether the environment expands the levels of
severity beyond the five standard levels and those
defined using addseverity(). The values accepted on the
initial call are saved for future calls.
Use in Applications
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.
The table below indicates the null values and identifiers for fmtmsg()
arguments.
┌─────────────────────────────────────────────────────────────────┐
│ Argument Type Null-Value Identifier │
│label char* (char*) NULL MM_NULLLBL │
│severity int 0 MM_NULLSEV │
│class long 0L MM_NULLMC │
│text char* (char*) NULL MM_NULLTXT │
│action char* (char*) NULL MM_NULLACT │
│tag char* (char*) NULL MM_NULLTAG │
└─────────────────────────────────────────────────────────────────┘
Another means of systematically omitting a component is by omitting the
component keyword(s) when defining the MSGVERB environment variable
(see the Environment Variables section above).
RETURN VALUES
The fmtmsg() returns 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 the
standard error stream, but otherwise succeeded.
MM_NOCON The function was unable to generate a console message,
but otherwise succeeded.
EXAMPLES
Example 1: The following example of fmtmsg():
fmtmsg(MM_PRINT, "UX:cat", MM_ERROR, "invalid syntax",
"refer to manual", "UX:cat:001")
produces a complete message in the standard message format:
UX:cat: ERROR: invalid syntax
TO FIX: refer to manual UX:cat:001
Example 2: When the environment variable MSGVERB is set as follows:
MSGVERB=severity:text:action
and the Example 1 is used, fmtmsg() produces:
ERROR: invalid syntax
TO FIX: refer to manual
Example 3: When the environment variable SEV_LEVEL is set as follows:
SEV_LEVEL=note,5,NOTE
the following call to fmtmsg()
fmtmsg(MM_UTIL | MM_PRINT, "UX:cat", 5, "invalid syntax",
"refer to manual", "UX:cat:001")
produces
UX:cat: NOTE: invalid syntax
TO FIX: refer to manual UX:cat:001
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOfmtmsg(1), addseverity(3C), gettxt(3C), printf(3C), attributes(5),
standards(5)SunOS 5.10 24 Jul 2002 fmtmsg(3C)