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| 55 | <H2><A NAME="SECTION0082920000000000000000"></A><A NAME="minimal-example"></A> |
| 56 | <BR> |
| 57 | 6.29.2 Basic example |
| 58 | </H2> |
| 59 | |
| 60 | <P> |
| 61 | |
| 62 | <span class="versionnote">Changed in version 2.4: |
| 63 | formerly <tt class="function">basicConfig</tt> did not take any keyword |
| 64 | arguments.</span> |
| 65 | |
| 66 | <P> |
| 67 | The <tt class="module">logging</tt> package provides a lot of flexibility, and its |
| 68 | configuration can appear daunting. This section demonstrates that simple |
| 69 | use of the logging package is possible. |
| 70 | |
| 71 | <P> |
| 72 | The simplest example shows logging to the console: |
| 73 | |
| 74 | <P> |
| 75 | <div class="verbatim"><pre> |
| 76 | import logging |
| 77 | |
| 78 | logging.debug('A debug message') |
| 79 | logging.info('Some information') |
| 80 | logging.warning('A shot across the bows') |
| 81 | </pre></div> |
| 82 | |
| 83 | <P> |
| 84 | If you run the above script, you'll see this: |
| 85 | <div class="verbatim"><pre> |
| 86 | WARNING:root:A shot across the bows |
| 87 | </pre></div> |
| 88 | |
| 89 | <P> |
| 90 | Because no particular logger was specified, the system used the root logger. |
| 91 | The debug and info messages didn't appear because by default, the root |
| 92 | logger is configured to only handle messages with a severity of WARNING |
| 93 | or above. The message format is also a configuration default, as is the output |
| 94 | destination of the messages - <code>sys.stderr</code>. The severity level, |
| 95 | the message format and destination can be easily changed, as shown in |
| 96 | the example below: |
| 97 | |
| 98 | <P> |
| 99 | <div class="verbatim"><pre> |
| 100 | import logging |
| 101 | |
| 102 | logging.basicConfig(level=logging.DEBUG, |
| 103 | format='%(asctime)s %(levelname)s %(message)s', |
| 104 | filename='/tmp/myapp.log', |
| 105 | filemode='w') |
| 106 | logging.debug('A debug message') |
| 107 | logging.info('Some information') |
| 108 | logging.warning('A shot across the bows') |
| 109 | </pre></div> |
| 110 | |
| 111 | <P> |
| 112 | The <tt class="method">basicConfig()</tt> method is used to change the configuration |
| 113 | defaults, which results in output (written to <code>/tmp/myapp.log</code>) |
| 114 | which should look something like the following: |
| 115 | |
| 116 | <P> |
| 117 | <div class="verbatim"><pre> |
| 118 | 2004-07-02 13:00:08,743 DEBUG A debug message |
| 119 | 2004-07-02 13:00:08,743 INFO Some information |
| 120 | 2004-07-02 13:00:08,743 WARNING A shot across the bows |
| 121 | </pre></div> |
| 122 | |
| 123 | <P> |
| 124 | This time, all messages with a severity of DEBUG or above were handled, |
| 125 | and the format of the messages was also changed, and output went to the |
| 126 | specified file rather than the console. |
| 127 | |
| 128 | <P> |
| 129 | Formatting uses standard Python string formatting - see section |
| 130 | <A href="typesseq-strings.html#typesseq-strings">2.3.6</A>. The format string takes the following |
| 131 | common specifiers. For a complete list of specifiers, consult the |
| 132 | <tt class="class">Formatter</tt> documentation. |
| 133 | |
| 134 | <P> |
| 135 | <div class="center"><table class="realtable"> |
| 136 | <thead> |
| 137 | <tr> |
| 138 | <th class="left" >Format</th> |
| 139 | <th class="left" >Description</th> |
| 140 | </tr> |
| 141 | </thead> |
| 142 | <tbody> |
| 143 | <tr><td class="left" valign="baseline"><code>%(name)s</code></td> |
| 144 | <td class="left" >Name of the logger (logging channel).</td></tr> |
| 145 | <tr><td class="left" valign="baseline"><code>%(levelname)s</code></td> |
| 146 | <td class="left" >Text logging level for the message |
| 147 | (<code>'DEBUG'</code>, <code>'INFO'</code>, |
| 148 | <code>'WARNING'</code>, <code>'ERROR'</code>, |
| 149 | <code>'CRITICAL'</code>).</td></tr> |
| 150 | <tr><td class="left" valign="baseline"><code>%(asctime)s</code></td> |
| 151 | <td class="left" >Human-readable time when the <tt class="class">LogRecord</tt> |
| 152 | was created. By default this is of the form |
| 153 | ``2003-07-08 16:49:45,896'' (the numbers after the |
| 154 | comma are millisecond portion of the time).</td></tr> |
| 155 | <tr><td class="left" valign="baseline"><code>%(message)s</code></td> |
| 156 | <td class="left" >The logged message.</td></tr></tbody> |
| 157 | </table></div> |
| 158 | |
| 159 | <P> |
| 160 | To change the date/time format, you can pass an additional keyword parameter, |
| 161 | <var>datefmt</var>, as in the following: |
| 162 | |
| 163 | <P> |
| 164 | <div class="verbatim"><pre> |
| 165 | import logging |
| 166 | |
| 167 | logging.basicConfig(level=logging.DEBUG, |
| 168 | format='%(asctime)s %(levelname)-8s %(message)s', |
| 169 | datefmt='%a, %d %b %Y %H:%M:%S', |
| 170 | filename='/temp/myapp.log', |
| 171 | filemode='w') |
| 172 | logging.debug('A debug message') |
| 173 | logging.info('Some information') |
| 174 | logging.warning('A shot across the bows') |
| 175 | </pre></div> |
| 176 | |
| 177 | <P> |
| 178 | which would result in output like |
| 179 | |
| 180 | <P> |
| 181 | <div class="verbatim"><pre> |
| 182 | Fri, 02 Jul 2004 13:06:18 DEBUG A debug message |
| 183 | Fri, 02 Jul 2004 13:06:18 INFO Some information |
| 184 | Fri, 02 Jul 2004 13:06:18 WARNING A shot across the bows |
| 185 | </pre></div> |
| 186 | |
| 187 | <P> |
| 188 | The date format string follows the requirements of <tt class="function">strftime()</tt> - |
| 189 | see the documentation for the <tt class="module"><a href="module-time.html">time</a></tt> module. |
| 190 | |
| 191 | <P> |
| 192 | If, instead of sending logging output to the console or a file, you'd rather |
| 193 | use a file-like object which you have created separately, you can pass it |
| 194 | to <tt class="function">basicConfig()</tt> using the <var>stream</var> keyword argument. Note |
| 195 | that if both <var>stream</var> and <var>filename</var> keyword arguments are passed, |
| 196 | the <var>stream</var> argument is ignored. |
| 197 | |
| 198 | <P> |
| 199 | Of course, you can put variable information in your output. To do this, |
| 200 | simply have the message be a format string and pass in additional arguments |
| 201 | containing the variable information, as in the following example: |
| 202 | |
| 203 | <P> |
| 204 | <div class="verbatim"><pre> |
| 205 | import logging |
| 206 | |
| 207 | logging.basicConfig(level=logging.DEBUG, |
| 208 | format='%(asctime)s %(levelname)-8s %(message)s', |
| 209 | datefmt='%a, %d %b %Y %H:%M:%S', |
| 210 | filename='/temp/myapp.log', |
| 211 | filemode='w') |
| 212 | logging.error('Pack my box with %d dozen %s', 5, 'liquor jugs') |
| 213 | </pre></div> |
| 214 | |
| 215 | <P> |
| 216 | which would result in |
| 217 | |
| 218 | <P> |
| 219 | <div class="verbatim"><pre> |
| 220 | Wed, 21 Jul 2004 15:35:16 ERROR Pack my box with 5 dozen liquor jugs |
| 221 | </pre></div> |
| 222 | |
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| 259 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
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