FMTMSG(3C-SVR4) RISC/os Reference Manual FMTMSG(3C-SVR4)
NAME
fmtmsg - 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
Based on a message's classification component, fmtmsg writes
a formatted message to stderr, to the console, or to both.
fmtmsg can be used instead of the traditional printf inter-
face to display messages to stderr. fmtmsg, in conjunction
with gettxt, provides a simple interface for producing
language-independent applications.
A formatted message consists of up to five standard com-
ponents as defined below. The component, classification, 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
identifier 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. Iden-
tifiers are: MM_APPL (application), MM_UTIL (util-
ity), and MM_OPSYS (operating system).
Display subclassifications indicate where the mes-
sage 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 identif-
iers may be used.
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Status subclassifications indicate whether the
application will recover from the condition. Iden-
tifiers 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 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 appli-
cation resides as well as the program or application
name. For example, the label UX:cat indicates the
UNIX System V package and the cat application.
severity
Indicates the seriousness of the condition. Identif-
iers 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
addseverity 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: TO FIX: . The action string is not
limited to a specific size.
tag An identifier which references on-line documentation
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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
There are two environment variables that control the
behavior of fmtmsg: MSGVERB and SEV_LEVEL.
MSGVERB tells fmtmsg which message components it is to
select when writing messages to stderr. The value of
MSGVERB is a colon-separated list of optional keywords.
MSGVERB 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 mes-
sage to stderr. If MSGVERB does not include a keyword for a
message component, that component 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 keywords other than the valid ones listed
above, fmtmsg selects all components.
The first time fmtmsg is called, it examines the MSGVERB
environment variable to see which message components it is
to select when generating a message to write to the standard
error stream, stderr. The values accepted on the initial
call are saved for future calls.
MSGVERB affects only which components are selected for
display to the standard error stream. All message com-
ponents are included in console messages.
SEV_LEVEL defines severity levels and associates print
strings with them for use by fmtmsg. The standard severity
levels shown below cannot be modified. Additional severity
levels can also be defined, redefined, and removed using
addseverity [see addseverity(3C)]. If the same severity
level is defined by both SEV_LEVEL and addseverity, the
definition by addseverity is controlling.
0 (no severity is used)
1 HALT
2 ERROR
3 WARNING
4 INFO
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SEV_LEVEL can be set as follows:
SEV_LEVEL=[description[:description[:...]]]
export SEV_LEVEL
description is a comma-separated list containing three
fields:
description=severity_keyword,level,printstring
severity_keyword is a character string that is used as the
keyword on the -s severity option to the fmtmsg command.
(This field is not used by the fmtmsg function.)
level 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.
printstring 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 see 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 messages generated by an application by using the null
value of the argument for that component.
The table below indicates the null values and identifiers
for fmtmsg arguments.
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______________________________________________
|_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 sec-
tion).
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
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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 syn-
tax", "refer to manual", "UX:cat:001")
produces:
UX:cat: NOTE: invalid syntax
TO FIX: refer to manual UX:cat:001
SEE ALSO
addseverity(3C-SVR4), gettxt(3C-SVR4), printf(3S-SVR4).
fmtmsg(1) in the User's Reference Manual.
DIAGNOSTICS
The exit codes for fmtmsg are the following:
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 suc-
ceeded.
MM_NOCON The function was unable to generate a console
message, but otherwise succeeded.
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