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1page.title=logcat
2parent.title=Tools
3parent.link=index.html
4@jd:body
5
6  <p>The Android logging system provides a mechanism for collecting and viewing system debug
7  output. Logs from various applications and portions of the system are collected in a series of
8  circular buffers, which then can be viewed and filtered by the <code>logcat</code> command. You can use
9  <code>logcat</code> from an ADB shell to view the log messages.</p>
10
11  <p>This document is a reference to the available command line options. For more information on <code>logcat</code>, see
12  <a href="{@docRoot}guide/developing/debugging/debugging-log.html">Reading and Writing Logs</a>.
13For more
14  information on accessing <code>logcat</code> from DDMS, instead of the command line, see the documentation for the
15  <a href="{@docRoot}guide/developing/debugging/ddms.html">Dalvik Debug Monitor Server</a>.
16  </p>
17
18  <h3>Syntax</h3>
19  <pre>
20[adb] logcat [&lt;option&gt;] ... [&lt;filter-spec&gt;] ...
21</pre>
22
23  <p>You can run <code>logcat</code> as an adb command or directly in a shell prompt
24  of your emulator or connected device. To view log output using adb, navigate to your SDK
25  <code>platform-tools/</code> directory and execute:</p>
26  <pre>
27$ adb logcat
28</pre>
29
30  <p>You can create a shell connection to a device and execute:</p>
31  <pre>
32$ adb shell
33# logcat
34</pre>
35
36  <h3>Options</h3>
37  <p>The following table describes the command line options of <code>logcat</code>.</p>
38
39  <table>
40    <tr>
41      <th>Option</th>
42
43      <th>Description</th>
44    </tr>
45
46    <tr>
47      <td><code>-b&nbsp;&lt;buffer&gt;</code></td>
48
49      <td>Loads an alternate log buffer for viewing, such as <code>event</code> or
50      <code>radio</code>. The <code>main</code> buffer is used by default. See <a href=
51      "#alternativebuffers">Viewing Alternative Log Buffers</a>.</td>
52    </tr>
53
54    <tr>
55      <td><code>-c</code></td>
56
57      <td>Clears (flushes) the entire log and exits.</td>
58    </tr>
59
60    <tr>
61      <td><code>-d</code></td>
62
63      <td>Dumps the log to the screen and exits.</td>
64    </tr>
65
66    <tr>
67      <td><code>-f&nbsp;&lt;filename&gt;</code></td>
68
69      <td>Writes log message output to <code>&lt;filename&gt;</code>. The default is
70      <code>stdout</code>.</td>
71    </tr>
72
73    <tr>
74      <td><code>-g</code></td>
75
76      <td>Prints the size of the specified log buffer and exits.</td>
77    </tr>
78
79    <tr>
80      <td><code>-n&nbsp;&lt;count&gt;</code></td>
81
82      <td>Sets the maximum number of rotated logs to <code>&lt;count&gt;</code>. The default value
83      is 4. Requires the <code>-r</code> option.</td>
84    </tr>
85
86    <tr>
87      <td><code>-r&nbsp;&lt;kbytes&gt;</code></td>
88
89      <td>Rotates the log file every <code>&lt;kbytes&gt;</code> of output. The default value is
90      16. Requires the <code>-f</code> option.</td>
91    </tr>
92
93    <tr>
94      <td><code>-s</code></td>
95
96      <td>Sets the default filter spec to silent.</td>
97    </tr>
98
99    <tr>
100      <td><code>-v&nbsp;&lt;format&gt;</code></td>
101
102      <td>Sets the output format for log messages. The default is <code>brief</code> format. For a
103      list of supported formats, see <a href="#outputformat">Controlling Log Output
104      Format</a>.</td>
105    </tr>
106  </table>
107