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<html>
<head>
<title>svlogd(8) manual page</title>
</head>
<body bgcolor='white'>
<a href='http://smarden.org/pape/'>G. Pape</a><br><a href='index.html'>runit</A><hr><p>
<h2><a name='sect0'>Name</a></h2>
svlogd - runit’s service logging daemon
<h2><a name='sect1'>Synopsis</a></h2>
<b>svlogd</b> [-tttv] [-r <i>c]</i> [-R
<i>xyz]</i> [-l <i>len]</i> [-b <i>buflen]</i> <i>logs</i>
<h2><a name='sect2'>Description</a></h2>
<i>logs</i> consists of one or more arguments,
each specifying a directory. <p>
<b>svlogd</b> continuously reads log data from its
standard input, optionally filters log messages, and writes the data to
one or more automatically rotated <i>logs</i>. <p>
Recent log files can automatically
be processed by an arbitrary processor program when they are rotated, and
<b>svlogd</b> can be told to alert selected log messages to standard error, and
through udp. <p>
<b>svlogd</b> runs until it sees end-of-file on standard input or is
sent a TERM signal, see below.
<h3><a name='sect3'>Log Directory</a></h3>
A log directory <i>log</i> contains
some number of old log files, and the current log file <i>current</i>. Old log
files have a file name starting with <i>@</i> followed by a precise timestamp
(see the daemontools’ <b>tai64n</b> program), indicating when <i>current</i> was rotated
and renamed to this file. <p>
A log directory additionally contains the lock
file <i>lock</i>, maybe <i>state</i> and <i>newstate</i>, and optionally the file <i>config</i>. <b>svlogd</b>
creates necessary files if they don’t exist. <p>
If <b>svlogd</b> has trouble opening
a log directory, it prints a warning, and ignores this log directory. If
<b>svlogd</b> is unable to open all log directories given at the command line,
it exits with an error. This can happen on start-up or after receiving a
HUP signal.
<h3><a name='sect4'>Log File Rotation</a></h3>
<b>svlogd</b> appends selected log messages to the
<i>current</i> log file. If <i>current</i> has <i>size</i> bytes or more (or there is a new-line
within the last <i>len</i> of <i>size</i> bytes), or is older than a specified amount
of <i>time</i>, <i>current</i> is rotated: <p>
<b>svlogd</b> closes <i>current</i>, changes permission
of <i>current</i> to 0755, renames <i>current</i> to @<i>timestamp.s,</i> and starts with a new
empty <i>current</i>. If <b>svlogd</b> sees <i>num</i> or more old log files in the log directory,
it removes the oldest one. Note that this doesn’t decrease the number of
log files if there are already more than <i>num</i> log files, this must be done
manually, e.g. for keeping 10 log files: <p>
ls -1 \@* |sort |sed -ne ’10,$p’ |xargs
rm<br>
<h3><a name='sect5'>Processor</a></h3>
If <b>svlogd</b> is told to process recent log files, it saves <i>current</i>
to @<i>timestamp.u,</i> feeds @<i>timestamp.u</i> through ‘‘sh -c "<i>processor</i>"’’ and writes the
output to @<i>timestamp.t.</i> If the <i>processor</i> finishes successfully, @<i>timestamp.t</i>
is renamed to @<i>timestamp.s,</i> and @<i>timestamp.u</i> is deleted; otherwise @<i>timestamp.t</i>
is deleted and the <i>processor</i> is started again. <b>svlogd</b> also saves any output
that the <i>processor</i> writes to file descriptor 5, and makes that output available
on file descriptor 4 when running <i>processor</i> on the next log file rotation.
<p>
A <i>processor</i> is run in the background. If <b>svlogd</b> sees a previously started
<i>processor</i> still running when trying to start a new one for the same <i>log</i>,
it blocks until the currently running <i>processor</i> has finished successfully.
Only the HUP signal works in that situation. Note that this may block any
program feeding its log data to <b>svlogd.</b>
<p>
<h3><a name='sect6'>Config</a></h3>
On startup, and after receiving
a HUP signal, <b>svlogd</b> checks for each log directory <i>log</i> if the configuration
file <i>log/config</i> exists, and if so, reads the file line by line and adjusts
configuration for <i>log</i> as follows: <p>
If the line is empty, or starts with
a ‘‘#’’, it is ignored. A line of the form
<dl>
<dt>s<i>size</i> </dt>
<dd>sets the maximum file size
of <i>current</i> when <b>svlogd</b> should rotate the current log file to <i>size</i> bytes.
Default is 1000000. If <i>size</i> is zero, <b>svlogd</b> doesn’t rotate log files. You
should set <i>size</i> to at least (2 * <i>len</i>). </dd>
<dt>n<i>num</i> </dt>
<dd>sets the number of old log files
<b>svlogd</b> should maintain to <i>num</i>. If <b>svlogd</b> sees more that <i>num</i> old log files
in <i>log</i> after log file rotation, it deletes the oldest one. Default is 10.
If <i>num</i> is zero, <b>svlogd</b> doesn’t remove old log files. </dd>
<dt>N<i>min</i> </dt>
<dd>sets the minimum
number of old log files <b>svlogd</b> should maintain to <i>min</i>. <i>min</i> must be less
than <i>num</i>. If <i>min</i> is set, and <b>svlogd</b> cannot write to <i>current</i> because the
filesystem is full, and it sees more than <i>min</i> old log files, it deletes
the oldest one. </dd>
<dt>t<i>timeout</i> </dt>
<dd>sets the maximum age of the <i>current</i> log file when
<b>svlogd</b> should rotate the current log file to <i>timeout</i> seconds. If <i>current</i>
is <i>timeout</i> seconds old, and is not empty, <b>svlogd</b> forces log file rotation.
</dd>
<dt>!<i>processor</i> </dt>
<dd>tells <b>svlogd</b> to feed each recent log file through <i>processor</i>
(see above) on log file rotation. By default log files are not processed.
</dd>
<dt>u<i>a.b.c.d[:port]</i> </dt>
<dd>tells <b>svlogd</b> to transmit the first <i>len</i> characters of selected
log messages to the IP address <i>a.b.c.d</i>, port number <i>port</i>. If <i>port</i> isn’t set,
the default port for syslog is used (514). <i>len</i> can be set through the -l
option, see below. If <b>svlogd</b> has trouble sending udp packets, it writes
error messages to the log directory. Attention: logging through udp is unreliable,
and should be used in private networks only. </dd>
<dt>U<i>a.b.c.d[:port]</i> </dt>
<dd>is the same as
the <i>u</i> line above, but the log messages are no longer written to the log
directory, but transmitted through udp only. Error messages from <b>svlogd</b>
concerning sending udp packages still go to the log directory. </dd>
<dt>p<i>prefix</i> </dt>
<dd>tells
<b>svlogd</b> to prefix each line to be written to the log directory, to standard
error, or through UDP, with <i>prefix</i>. </dd>
</dl>
<p>
If a line starts with a <i>-</i>, <i>+</i>, <i>e</i>, or <i>E</i>,
<b>svlogd</b> matches the first <i>len</i> characters of each log message against <i>pattern</i>
and acts accordingly:
<dl>
<dt>-<i>pattern</i> </dt>
<dd>the log message is deselected. </dd>
<dt>+<i>pattern</i> </dt>
<dd>the
log message is selected. </dd>
<dt>e<i>pattern</i> </dt>
<dd>the log message is selected to be printed
to standard error. </dd>
<dt>E<i>pattern</i> </dt>
<dd>the log message is deselected to be printed
to standard error. </dd>
</dl>
<p>
Initially each line is selected to be written to <i>log/current</i>.
Deselected log messages are discarded from <i>log</i>. Initially each line is deselected
to be written to standard err. Log messages selected for standard error
are written to standard error.
<h2><a name='sect7'>Pattern Matching</a></h2>
<b>svlogd</b> matches a log message
against the string <i>pattern</i> as follows: <p>
<i>pattern</i> is applied to the log message
one character by one, starting with the first. A character not a star (‘‘*’’)
and not a plus (‘‘+’’) matches itself. A plus matches the next character in
<i>pattern</i> in the log message one or more times. A star before the end of <i>pattern</i>
matches any string in the log message that does not include the next character
in <i>pattern</i>. A star at the end of <i>pattern</i> matches any string. <p>
Timestamps optionally
added by <b>svlogd</b> are not considered part of the log message. <p>
An <b>svlogd</b> pattern
is not a regular expression. For example consider a log message like this
<p>
2005-12-18_09:13:50.97618 tcpsvd: info: pid 1977 from 10.4.1.14<br>
<p>
The following pattern doesn’t match <p>
-*pid*<br>
<p>
because the first star matches up to the first p in tcpsvd, and then the
match fails because i is not s. To match this log message, you can use a
pattern like this instead <p>
-*: *: pid *<br>
<h2><a name='sect8'>Options</a></h2>
<dl>
<dt><b>-t</b> </dt>
<dd>timestamp. Prefix each selected line with a precise timestamp
(see the daemontools’ <b>tai64n</b> program) when writing to <i>log</i> or to standard
error. </dd>
<dt><b>-tt</b> </dt>
<dd>timestamp. Prefix each selected line with a human readable, sortable
UTC timestamp of the form YYYY-MM-DD_HH:MM:SS.xxxxx when writing to <i>log</i> or
to standard error. </dd>
<dt><b>-ttt</b> </dt>
<dd>timestamp. Prefix each selected line with a human
readable, sortable UTC timestamp of the form YYYY-MM-DDTHH:MM:SS.xxxxx when
writing to <i>log</i> or to standard error. </dd>
<dt><b>-r <i>c</b> </i></dt>
<dd>replace. <i>c</i> must be a single character.
Replace non-printable characters in log messages with <i>c</i>. Characters are replaced
before pattern matching is applied. </dd>
<dt><b>-R <i>xyz</b> </i></dt>
<dd>replace charset. Additionally to
non-printable characters, replace all characters found in <i>xyz</i> with <i>c</i> (default
‘‘_’’). </dd>
<dt><b>-l <i>len</b> </i></dt>
<dd>line length. Pattern matching applies to the first <i>len</i> characters
of a log message only. Default is 1000. </dd>
<dt><b>-b <i>buflen</b> </i></dt>
<dd>buffer size. Set the size
of the buffer <b>svlogd</b> uses when reading from standard input and writing
to <i>logs</i> to <i>buflen</i>. Default is 1024. <i>buflen</i> must be greater than <i>len</i>. For <b>svlogd</b>
instances that process a lot of data in short time, the buffer size should
be increased to improve performance. </dd>
<dt><b>-v</b> </dt>
<dd>verbose. Print verbose messages to
standard error. </dd>
</dl>
<h2><a name='sect9'>Signals</a></h2>
If <b>svlogd</b> is sent a HUP signal, it closes and reopens
all <i>logs</i>, and updates their configuration according to <i>log/config</i>. If <b>svlogd</b>
has trouble opening a log directory, it prints a warning, and discards
this log directory. If <b>svlogd</b> is unable to open all log directories given
at the command line, it exits with an error. <p>
If <b>svlogd</b> is sent a TERM signal,
or if it sees end-of-file on standard input, it stops reading standard input,
processes the data in the buffer, waits for all <i>processor</i> subprocesses
to finish if any, and exits 0 as soon as possible. <p>
If <b>svlogd</b> is sent an
ALRM signal, it forces log file rotation for all <i>logs</i> with a non empty
<i>current</i> log file.
<h2><a name='sect10'>See Also</a></h2>
<i>sv(8)</i>, <i>runsv(8)</i>, <i>chpst(8)</i>, <i>runit(8)</i>, <i>runit-init(8)</i>,
<i>runsvdir(8)</i>, <i>runsvchdir(8)</i> <p>
<i>http://smarden.org/runit/</i>
<h2><a name='sect11'>Author</a></h2>
Gerrit Pape <pape@smarden.org>
<p>
<hr><p>
<a name='toc'><b>Table of Contents</b></a><p>
<ul>
<li><a name='toc0' href='#sect0'>Name</a></li>
<li><a name='toc1' href='#sect1'>Synopsis</a></li>
<li><a name='toc2' href='#sect2'>Description</a></li>
<ul>
<li><a name='toc3' href='#sect3'>Log Directory</a></li>
<li><a name='toc4' href='#sect4'>Log File Rotation</a></li>
<li><a name='toc5' href='#sect5'>Processor</a></li>
<li><a name='toc6' href='#sect6'>Config</a></li>
</ul>
<li><a name='toc7' href='#sect7'>Pattern Matching</a></li>
<li><a name='toc8' href='#sect8'>Options</a></li>
<li><a name='toc9' href='#sect9'>Signals</a></li>
<li><a name='toc10' href='#sect10'>See Also</a></li>
<li><a name='toc11' href='#sect11'>Author</a></li>
</ul>
</body>
</html>
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