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| <h4 class="subsection">12.22.1 Printing Formatted Messages</h4> |
| |
| <p>Messages can be printed to standard error and/or to the console. To |
| select the destination the programmer can use the following two values, |
| bitwise OR combined if wanted, for the <var>classification</var> parameter of |
| <code>fmtmsg</code>: |
| |
| <dl> |
| <dt><code>MM_PRINT</code><a name="index-MM_005fPRINT-1172"></a><dd>Display the message in standard error. |
| <br><dt><code>MM_CONSOLE</code><a name="index-MM_005fCONSOLE-1173"></a><dd>Display the message on the system console. |
| </dl> |
| |
| <p>The erroneous piece of the system can be signalled by exactly one of the |
| following values which also is bitwise ORed with the |
| <var>classification</var> parameter to <code>fmtmsg</code>: |
| |
| <dl> |
| <dt><code>MM_HARD</code><a name="index-MM_005fHARD-1174"></a><dd>The source of the condition is some hardware. |
| <br><dt><code>MM_SOFT</code><a name="index-MM_005fSOFT-1175"></a><dd>The source of the condition is some software. |
| <br><dt><code>MM_FIRM</code><a name="index-MM_005fFIRM-1176"></a><dd>The source of the condition is some firmware. |
| </dl> |
| |
| <p>A third component of the <var>classification</var> parameter to <code>fmtmsg</code> |
| can describe the part of the system which detects the problem. This is |
| done by using exactly one of the following values: |
| |
| <dl> |
| <dt><code>MM_APPL</code><a name="index-MM_005fAPPL-1177"></a><dd>The erroneous condition is detected by the application. |
| <br><dt><code>MM_UTIL</code><a name="index-MM_005fUTIL-1178"></a><dd>The erroneous condition is detected by a utility. |
| <br><dt><code>MM_OPSYS</code><a name="index-MM_005fOPSYS-1179"></a><dd>The erroneous condition is detected by the operating system. |
| </dl> |
| |
| <p>A last component of <var>classification</var> can signal the results of this |
| message. Exactly one of the following values can be used: |
| |
| <dl> |
| <dt><code>MM_RECOVER</code><a name="index-MM_005fRECOVER-1180"></a><dd>It is a recoverable error. |
| <br><dt><code>MM_NRECOV</code><a name="index-MM_005fNRECOV-1181"></a><dd>It is a non-recoverable error. |
| </dl> |
| |
| <!-- fmtmsg.h --> |
| <!-- XPG --> |
| <div class="defun"> |
| — Function: int <b>fmtmsg</b> (<var>long int classification, const char *label, int severity, const char *text, const char *action, const char *tag</var>)<var><a name="index-fmtmsg-1182"></a></var><br> |
| <blockquote><p>Display a message described by its parameters on the device(s) specified |
| in the <var>classification</var> parameter. The <var>label</var> parameter |
| identifies the source of the message. The string should consist of two |
| colon separated parts where the first part has not more than 10 and the |
| second part not more than 14 characters. The <var>text</var> parameter |
| describes the condition of the error, the <var>action</var> parameter possible |
| steps to recover from the error and the <var>tag</var> parameter is a |
| reference to the online documentation where more information can be |
| found. It should contain the <var>label</var> value and a unique |
| identification number. |
| |
| <p>Each of the parameters can be a special value which means this value |
| is to be omitted. The symbolic names for these values are: |
| |
| <dl> |
| <dt><code>MM_NULLLBL</code><a name="index-MM_005fNULLLBL-1183"></a><dd>Ignore <var>label</var> parameter. |
| <br><dt><code>MM_NULLSEV</code><a name="index-MM_005fNULLSEV-1184"></a><dd>Ignore <var>severity</var> parameter. |
| <br><dt><code>MM_NULLMC</code><a name="index-MM_005fNULLMC-1185"></a><dd>Ignore <var>classification</var> parameter. This implies that nothing is |
| actually printed. |
| <br><dt><code>MM_NULLTXT</code><a name="index-MM_005fNULLTXT-1186"></a><dd>Ignore <var>text</var> parameter. |
| <br><dt><code>MM_NULLACT</code><a name="index-MM_005fNULLACT-1187"></a><dd>Ignore <var>action</var> parameter. |
| <br><dt><code>MM_NULLTAG</code><a name="index-MM_005fNULLTAG-1188"></a><dd>Ignore <var>tag</var> parameter. |
| </dl> |
| |
| <p>There is another way certain fields can be omitted from the output to |
| standard error. This is described below in the description of |
| environment variables influencing the behavior. |
| |
| <p>The <var>severity</var> parameter can have one of the values in the following |
| table: |
| <a name="index-severity-class-1189"></a> |
| <dl> |
| <dt><code>MM_NOSEV</code><a name="index-MM_005fNOSEV-1190"></a><dd>Nothing is printed, this value is the same as <code>MM_NULLSEV</code>. |
| <br><dt><code>MM_HALT</code><a name="index-MM_005fHALT-1191"></a><dd>This value is printed as <code>HALT</code>. |
| <br><dt><code>MM_ERROR</code><a name="index-MM_005fERROR-1192"></a><dd>This value is printed as <code>ERROR</code>. |
| <br><dt><code>MM_WARNING</code><a name="index-MM_005fWARNING-1193"></a><dd>This value is printed as <code>WARNING</code>. |
| <br><dt><code>MM_INFO</code><a name="index-MM_005fINFO-1194"></a><dd>This value is printed as <code>INFO</code>. |
| </dl> |
| |
| <p>The numeric value of these five macros are between <code>0</code> and |
| <code>4</code>. Using the environment variable <code>SEV_LEVEL</code> or using the |
| <code>addseverity</code> function one can add more severity levels with their |
| corresponding string to print. This is described below |
| (see <a href="Adding-Severity-Classes.html#Adding-Severity-Classes">Adding Severity Classes</a>). |
| |
| <p class="noindent">If no parameter is ignored the output looks like this: |
| |
| <pre class="smallexample"> <var>label</var>: <var>severity-string</var>: <var>text</var> |
| TO FIX: <var>action</var> <var>tag</var> |
| </pre> |
| <p>The colons, new line characters and the <code>TO FIX</code> string are |
| inserted if necessary, i.e., if the corresponding parameter is not |
| ignored. |
| |
| <p>This function is specified in the X/Open Portability Guide. It is also |
| available on all systems derived from System V. |
| |
| <p>The function returns the value <code>MM_OK</code> if no error occurred. If |
| only the printing to standard error failed, it returns <code>MM_NOMSG</code>. |
| If printing to the console fails, it returns <code>MM_NOCON</code>. If |
| nothing is printed <code>MM_NOTOK</code> is returned. Among situations where |
| all outputs fail this last value is also returned if a parameter value |
| is incorrect. |
| </p></blockquote></div> |
| |
| <p>There are two environment variables which influence the behavior of |
| <code>fmtmsg</code>. The first is <code>MSGVERB</code>. It is used to control the |
| output actually happening on standard error (<em>not</em> the console |
| output). Each of the five fields can explicitly be enabled. To do |
| this the user has to put the <code>MSGVERB</code> variable with a format like |
| the following in the environment before calling the <code>fmtmsg</code> function |
| the first time: |
| |
| <pre class="smallexample"> MSGVERB=<var>keyword</var>[:<var>keyword</var>[:...]] |
| </pre> |
| <p>Valid <var>keyword</var>s are <code>label</code>, <code>severity</code>, <code>text</code>, |
| <code>action</code>, and <code>tag</code>. If the environment variable is not given |
| or is the empty string, a not supported keyword is given or the value is |
| somehow else invalid, no part of the message is masked out. |
| |
| <p>The second environment variable which influences the behavior of |
| <code>fmtmsg</code> is <code>SEV_LEVEL</code>. This variable and the change in the |
| behavior of <code>fmtmsg</code> is not specified in the X/Open Portability |
| Guide. It is available in System V systems, though. It can be used to |
| introduce new severity levels. By default, only the five severity levels |
| described above are available. Any other numeric value would make |
| <code>fmtmsg</code> print nothing. |
| |
| <p>If the user puts <code>SEV_LEVEL</code> with a format like |
| |
| <pre class="smallexample"> SEV_LEVEL=[<var>description</var>[:<var>description</var>[:...]]] |
| </pre> |
| <p class="noindent">in the environment of the process before the first call to |
| <code>fmtmsg</code>, where <var>description</var> has a value of the form |
| |
| <pre class="smallexample"> <var>severity-keyword</var>,<var>level</var>,<var>printstring</var> |
| </pre> |
| <p>The <var>severity-keyword</var> part is not used by <code>fmtmsg</code> but it has |
| to be present. The <var>level</var> part is a string representation of a |
| number. The numeric value must be a number greater than 4. This value |
| must be used in the <var>severity</var> parameter of <code>fmtmsg</code> to select |
| this class. It is not possible to overwrite any of the predefined |
| classes. The <var>printstring</var> is the string printed when a message of |
| this class is processed by <code>fmtmsg</code> (see above, <code>fmtsmg</code> does |
| not print the numeric value but instead the string representation). |
| |
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