NAME
fmtmsg —
display a detailed diagnostic
message
LIBRARY
library “libc”
SYNOPSIS
#include
<fmtmsg.h>
int
fmtmsg(long classification,
const char *label, int severity,
const char *text, const char
*action, const char *tag);
DESCRIPTION
Thefmtmsg()
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
STANDARDS
The fmtmsg() function conforms to
IEEE Std 1003.1-2001 (“POSIX.1”).
HISTORY
The fmtmsg() function first appeared in
FreeBSD 5.0. It was imported into
DragonFly 2.1.
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.