1FMTMSG(3P) POSIX Programmer's Manual FMTMSG(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 fmtmsg — display a message in the specified format on standard error
13 and/or a system console
14
16 #include <fmtmsg.h>
17 int fmtmsg(long classification, const char *label, int severity,
19 const char *text, const char *action, const char *tag);
20
22 The fmtmsg() function shall display messages in a specified format
23 instead of the traditional printf() function.
24 Based on a message's classification component, fmtmsg() shall write a
26 formatted message either to standard error, to the console, or to both.
27 A formatted message consists of up to five components as defined below.
29 The component classification is not part of a message displayed to the
30 user, but defines the source of the message and directs the display of
31 the formatted message.
32 classification
34 Contains the sum of identifying values constructed from the
35 constants defined below. Any one identifier from a subclass
36 may be used in combination with a single identifier from a
37 different subclass. Two or more identifiers from the same
38 subclass should not be used together, with the exception of
39 identifiers from the display subclass. (Both display sub‐
40 class identifiers may be used so that messages can be dis‐
41 played to both standard error and the system console.)
42 Major Classifications
44 Identifies the source of the condition. Identifiers
45 are: MM_HARD (hardware), MM_SOFT (software), and
46 MM_FIRM (firmware).
47 Message Source Subclassifications
49 Identifies the type of software in which the problem
50 is detected. Identifiers are: MM_APPL (application),
51 MM_UTIL (utility), and MM_OPSYS (operating system).
52 Display Subclassifications
54 Indicates where the message is to be displayed. Iden‐
55 tifiers are: MM_PRINT to display the message on the
56 standard error stream, MM_CONSOLE to display the mes‐
57 sage on the system console. One or both identifiers
58 may be used.
59 Status Subclassifications
61 Indicates whether the application can recover from
62 the condition. Identifiers are: MM_RECOVER (recover‐
63 able) and MM_NRECOV (non-recoverable).
64 An additional identifier, MM_NULLMC, indicates that no
66 classification component is supplied for the message.
67 label Identifies the source of the message. The format is two
69 fields separated by a <colon>. The first field is up to 10
70 bytes, the second is up to 14 bytes.
71 severity Indicates the seriousness of the condition. Identifiers for
73 the levels of severity are:
74 MM_HALT Indicates that the application has encountered
76 a severe fault and is halting. Produces the
77 string "HALT".
78 MM_ERROR Indicates that the application has detected a
80 fault. Produces the string "ERROR".
81 MM_WARNING Indicates a condition that is out of the ordi‐
83 nary, that might be a problem, and should be
84 watched. Produces the string "WARNING".
85 MM_INFO Provides information about a condition that is
87 not in error. Produces the string "INFO".
88 MM_NOSEV Indicates that no severity level is supplied
90 for the message.
91 text Describes the error condition that produced the message.
93 The character string is not limited to a specific size. If
94 the character string is empty, then the text produced is
95 unspecified.
96 action Describes the first step to be taken in the error-recovery
98 process. The fmtmsg() function precedes the action string
99 with the prefix: "TOFIX:". The action string is not lim‐
100 ited to a specific size.
101 tag An identifier that references on-line documentation for the
103 message. Suggested usage is that tag includes the label
104 and a unique identifying number. A sample tag is
105 "XSI:cat:146".
106 The MSGVERB environment variable (for message verbosity) shall deter‐
108 mine for fmtmsg() which message components it is to select when writing
109 messages to standard error. The value of MSGVERB shall be a
110 <colon>-separated list of optional keywords. Valid keywords are: label,
111 severity, text, action, and tag. If MSGVERB contains a keyword for a
112 component and the component's value is not the component's null value,
113 fmtmsg() shall include that component in the message when writing the
114 message to standard error. If MSGVERB does not include a keyword for a
115 message component, that component shall not be included in the display
116 of the message. The keywords may appear in any order. If MSGVERB is not
117 defined, if its value is the null string, if its value is not of the
118 correct format, or if it contains keywords other than the valid ones
119 listed above, fmtmsg() shall select all components.
120 MSGVERB shall determine which components are selected for display to
122 standard error. All message components shall be included in console
123 messages.
124
126 The fmtmsg() function shall return one of the following values:
127 MM_OK The function succeeded.
129 MM_NOTOK The function failed completely.
131 MM_NOMSG The function was unable to generate a message on standard
133 error, but otherwise succeeded.
134 MM_NOCON The function was unable to generate a console message, but
136 otherwise succeeded.
137
139 None.
140 The following sections are informative.
142
144 1. The following example of fmtmsg():
145 fmtmsg(MM_PRINT, "XSI:cat", MM_ERROR, "illegal option",
148 "refer to cat in user's reference manual", "XSI:cat:001")
149 produces a complete message in the specified message format:
151 XSI:cat: ERROR: illegal option
154 TO FIX: refer to cat in user's reference manual XSI:cat:001
155 2. When the environment variable MSGVERB is set as follows:
157 MSGVERB=severity:text:action
160 and Example 1 is used, fmtmsg() produces:
162 ERROR: illegal option
165 TO FIX: refer to cat in user's reference manual
166
168 One or more message components may be systematically omitted from mes‐
169 sages generated by an application by using the null value of the argu‐
170 ment for that component.
171
173 None.
174
176 None.
177
179 fprintf()
180 The Base Definitions volume of POSIX.1‐2017, <fmtmsg.h>
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184 Portions of this text are reprinted and reproduced in electronic form
185 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
186 table Operating System Interface (POSIX), The Open Group Base Specifi‐
187 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
188 Electrical and Electronics Engineers, Inc and The Open Group. In the
189 event of any discrepancy between this version and the original IEEE and
190 The Open Group Standard, the original IEEE and The Open Group Standard
191 is the referee document. The original Standard can be obtained online
192 at http://www.opengroup.org/unix/online.html .
193 Any typographical or formatting errors that appear in this page are
195 most likely to have been introduced during the conversion of the source
196 files to man page format. To report such errors, see https://www.ker‐
197 nel.org/doc/man-pages/reporting_bugs.html .
198IEEE/The Open Group 2017 FMTMSG(3P)